Paleobiology of Climactichnites, 
*?5* an Enigmatic Late Cambrian Fossil 
Mte*.' 'm 
,LIS L. YOCHELSON 
and 
A. FEDONK: 
TO PALEOBIOLOGY ? NUMB 
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S M I T H S O N I A N C O N T R I B U T I O N S T O P A L E O B I O L O G Y ? N U M B E R 7 4 
Paleobiology of Climactichnites, 
an Enigmatic Late Cambrian Fossil 
Ellis L. Yochelson 
and Mikhail A. Fedonkin 
SMITHSONIAN INSTITUTION PRESS 
Washington, D.C. 
1993 
A B S T R A C T 
Yochelson, Ellis L., and Mikhail A. Fedonkin. Paleobiology of Climactichnites, an Enigmatic 
Late Cambrian Fossil. Smithsonian Contributions to Paleobiology, number 74, 74 pages, 
frontispiece, 58 figures, 1993.?Climactichnites wilsoni Logan, 1860, is redescribed from field 
investigations and specimens in various museums. Climactichnites youngi Todd, 1882, and C. 
fosteri Todd, 1882, are placed in synonymy. The species is known only from its trail, consisting 
of raised bars and impressed furrows, bounded by two parallel, raised lateral ridges. This 
structure is interpreted as being formed from damp sand, redistributed and molded by the animal. 
At a few localities, an oval impression occurs at the origin of the trail; a new locality for this rare 
feature was found in Wisconsin. In Quebec a trail crossing over itself was found; this 
phenomenon was known from only one other locality. 
All occurrences of Climactichnites are in the Late Cambrian; specimens are known from New 
York, Quebec, Ontario, Wisconsin, and Missouri. This fossil is probably confined to the 
Dresbachian, the earliest stage of the tri-part Late Cambrian. All examples of trails are in 
sandstones; these are interpreted as sand flats that were just above water during low tide in the 
shallow epicontinental sea. 
A variety of animals have been proposed as the trail maker; they include several different 
kinds of arthropods, mollusks, and "worms." Each proposal has weak points and none of the 
suggested animal groups has appropriate morphology to produce the marking. The animal is 
reconstructed as relatively low, broad, and about twice as long as wide. It is hypothesized that 
the tough body integument secreted mucus which facilitated movement and aided in 
preservation of the trail. A large flap covered most of the outside body and extended laterally 
over the muscular foot. Free edges of the flap on either side of the body compressed and molded 
damp sand into parallel bounding ridges. Respiratory organs may have been present below the 
flap edges, kept moist by being partially enclosed. By moving the edges of these lateral flaps, the 
organism may have been able to swim when in water. 
Most trails of Climactichnites are interpreted as a consequence of feeding activity. If so, food 
was taken in through a circular mouth located anteriorward on the ventral surface; this 
morphologic feature is inferred from circular markings seen on a few bars. As reconstructed, the 
sand under the animal was compressed anteriorly and laterally; the animal then brushed particles 
forward into a small dune-like bar, probably by the action of cilia on its ventral surface. Sand 
dwelling microorganisms displaced by brushing were concentrated centrally, obviating 
ingestion of large amounts of sediment. What sediment was taken in was released at irregular 
intervals through a posterior anus; medial marking on parts of some trails are interpreted as fecal 
strings. The complex clamping and brushing behavior, implies a well-developed nervous 
system. 
No body fossils are known in the Vendian or in the Paleozoic that could have constructed this 
form of trail. The proposed method of feeding, if correctly interpreted, is unique. Thus the trail 
of Climactichnites may constitute the work of an otherwise unknown phylum in the animal 
kingdom. 
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is 
recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The 
trilobite Phacops rana Green. 
Library of Congress Cataloging-in-Publication Data 
Yochelson, Ellis Leon, 1928-
Paleobiology of Climactichnites, an enigmatic Late Cambrian fossil / Ellis L. Yochelson and Mikhail A. Fedonkin. 
p. cm. ? (Smithsonian contributions to paleobiology ; no. 74) 
Includes bibliographic references. 
Supt. of Docs. no. SI 1.30:74 
1. Climatichnites. 2. Paleontology?Cambrian. I. Fedonkin, M.A. (Mikhail Aleksandrovich) II. Title. 
III. Series. 
QE701.S56 no. 74 [QE720.5] 560 s-dc20 [560] 92-43329 
0 The paper used in this publication meets the minimum requirements of the American 
National Standard for Permanence of Paper for Printed Library Materials Z39.48?1984. 
Contents 
Page 
Introduction 1 
Repositories 1 
Acknowledgments 2 
Historical Account 3 
Geographic Distribution 5 
Stratigraphic Range 9 
Environmental Setting 12 
Systematic Paleontology 18 
Phylum Incertae Sedis 18 
Genus Climactichnites Logan, 1860 19 
Climactichnites wilsoni Logan, 1860 19 
Details of Morphology 21 
Abundance and Size Distribution of Trails 33 
Earlier Views on the Origin of Climactichnites 35 
Comments on Earlier Hypotheses of Origin 44 
Alternative Hypotheses 63 
Paleoecological Interpretation of Climactichnites 63 
Feeding Behavior 64 
Locomotion and Trail Formation 65 
Climactichnites and the Early Ichnological Record 67 
Reconstruction of Climactichnites 68 
Ichnogenera and High-level Taxa 70 
Discussion 70 
Literature Cited 72 
in 
FRONTISPIECE.?A large slab on public display off the east side of the Rotunda on the first floor of the National 
Museum of Natural History, Smithsonian Institution, Washington, DC. This material was collected by CD. 
Walcott in 1886 from "Rogier's Farm, one mile west of Beauharnois, Quebec" (locality 10). Numerous trails of 
Climactichnites wilsoni Logan in varying orientation cover the surface of the ripple-marked slab of Late 
Cambrian "Potsdam" Sandstone. The area at the lower left bears faint markings of Protichnites, some of which 
obscure portions of the Climactichnites trails. Photograph by V. Krantz, USNM. 
Paleobiology of Climactichnites, 
an Enigmatic Late Cambrian Fossil 
Ellis L. Yochelson 
and Mikhail A. Fedonkin 
Introduction 
Clark and Usher (1948:261) wrote: "Of the few fossils found 
in the potsdam sandstone none have been of wider interest than 
Climactichnites.'" Not only is this an accurate statement, despite 
lack of capitalization of the formational name, but that work of 
more than four decades ago constitutes virtually the last 
contribution of new observations on this fossil. During 
September, 1990, we engaged in intensive field and laboratory 
investigation of this fossil in an effort to better characterize and 
understand it. Climactichnites Logan, 1860, is known only 
from its trail, which superficially resembles that of a 
motorcycle tire print; one, however, which was impressed on 
damp sand that has been hardened into rock for slightly more 
than 500 million years. 
In 1886, Charles Doolittle Walcott was interested in 
obtaining specimens of the coeval Protichnites Logan, a trace 
fossil which obviously possessed multiple legs and apparently 
a median spike-like posterior telson. As a result of his efforts, 
an exceptionally large slab containing numerous examples of 
both Climactichnites and Protichnites were collected from "a 
mile west of Beauharnois, Quebec" (Walcott, 1912:277). Four 
men were employed for almost a week in the quarrying of large 
pieces of a sandstone layer; the material removed probably 
weighs nearly three tons and transporting it from the outcrop to 
Washington, D.C. was a heroic operation. 
It is not known whether this sandstone was exhibited in the 
original United States National Museum, now the Arts and 
Industries Building (Smithsonian Institution, Washington, 
D.C), but for many years the slabs were displayed on a low 
pedestal in the Hall of Invertebrate Life in the "New National 
Museum" (National Museum of Natural History, Smithsonian 
Institution). Forty years later, when the exhibits were changed, 
Ellis L. Yochelson, Research Associate, Department of Paleobiology, 
National Museum of Natural History, Smithsonian Institution, 
Washington, D.C. 20560. Mikhail A. Fedonkin, Paleontological 
Institute, Russia Academy of Sciences, 117868 Moscow, Russia. 
they were placed in storage. When the paleontological displays 
were reconstructed for the third time, the stratum was carefully 
assembled and the cracks between pieces were restored by Mr. 
John Ott, under the general direction of Mr. Frederick J. 
Collier. The bedding plane now stands vertically, as the largest 
known public exhibit of Climactichnites, and serves as an 
introduction to the museum visitor of the wonders of the fossil 
record. Curiously, this bedding plane has never been illustrated, 
nor studied in detail. We reproduce this reconstructed bedding 
plane as an appropriate Frontispiece to our study. 
With this slab as the point of departure, the aim of our study 
is to summarize the geologic and geographic distribution of 
Climactichnites and to describe the characteristics of its trail, 
which is documented by a large number of specimens. From 
this information, we have attempted to interpret the ecology 
and life habit of the trace-maker. Finally, from this data and 
from our inferences we have reconstructed the morphology of 
the animal. Our photographic documentation permits those 
who may not accept our conclusions to consider further this 
most enigmatic, but most interesting, fossil. 
REPOSITORIES.?The following abbreviations are used for 
institutions housing specimens used in this study. 
AMNH American Museum of Natural History, New 
York, NY 
GSC Geological Survey of Canada, Ottawa, On?
tario, Canada 
Miller Museum, Queens University, Depart?
ment of Geological Science, Kingston, On?
tario, Canada 
MPM Milwaukee Public Museum, Milwaukee, WI 
NYSM New York State Museum, New York State 
Geological Survey collections, Albany, NY 
PNH Pratt Museum of Natural History, Amherst 
College, Department of Geology, Amherst, 
MA 
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
RM Peter Redpath Museum, McGill University, 
Montreal, Quebec, Canada 
ROM Royal Ontario Museum, Toronto, Ontario, 
Canada 
SMM-P Science Museum of Minnesota, St. Paul, MN 
USNM National Museum of Natural History (for?
merly the United States National Museum), 
Smithsonian Institution, Washington, DC 
ACKNOWLEDGMENTS.?Fedonkin thanks the Office of Fel?
lowship and Grants, Smithsonian Institution, for the opportu?
nity to visit Washington, D.C, under the short term visitors' 
program. Yochelson thanks the Office of the Director, National 
Museum of Natural History, for travel funds allowing both to 
examine Climactichnites on the outcrop and to study slabs with 
this fossil in the collections of a number of museums. The Field 
Museum of Natural History and Harvard University supported 
the travel of Fedonkin to examine specimens at those 
institutions. Late in 1990, Amherst College provided funds for 
a visit by Yochelson to examine specimens in the Pratt 
Museum, and in 1991 the University of Wisconsin provided 
funds for a visit by him to a new locality in that state. 
Many persons cooperated to make our field season a success. 
In Wisconsin, Mr. and Mrs. William Nemke, Harley, Wiscon?
sin, kindly allowed access to the Northern Stone Company 
quarry, and also contributed several specimens to the National 
collections. Dr. Jean L. Hoff, Department of Geology, 
University of Wisconsin-Eau Claire, guided us to choice 
specimens in the field, and later provided a large latex replica 
from one outcrop. Dr. Klaus Westphal, Geology Museum, 
University of Wisconsin-Madison, allowed access to an 
exhibited specimen in his charge. Dr. Robert H. Dott, Jr., 
Department of Geology and Geophysics, University of Wis?
consin-Madison, provided significant discussion, field data, 
and a field excursion in 1991. At the Milwaukee Public 
Museum, Dr. Peter M. Sheehan, allowed access to the fossil 
collections, and Ms. Paula Sumpter was particularly helpful in 
arranging for us to examine and photograph an exhibited 
specimen and further assisted with photography in the research 
collections. 
In Ontario, Ms. Janet B. Waddington, Royal Ontario 
Museum, Toronto, diligently searched the collections and 
found a hitherto unreported topotype of Climactichnites 
wilsoni. Dr. Guy M. Narbonne, Department of Geological 
Sciences, Queen's University, Kingston, allowed the photogra?
phy of two unusual slabs in the departmental collections of the 
Miller Museum (Yochelson and Fedonkin, 1991). He and Dr. 
Robert Dalrymple of that department provided significant 
discussion and field data. At Perth, Mr. Douglas McNicol, 
Curator of the Archibald W. Campbell Memorial Museum, 
located yet another topotype. In Ottawa, Dr. Thomas E. Bolton, 
Geological Survey of Canada, arranged for Sir William 
Logan's type slab to be uncrated and reassembled for our 
inspection. 
In Quebec, Ms. Delise Allison, Peter Redpath Museum, 
McGill University, greatly assisted in photography of a slab on 
display, earlier illustrated by Sir William Dawson, and located 
several plaster casts which he had made. At St. Hermas, Mme. 
Yvonne Leroux kindly permitted us to examine outcrops on her 
property. 
In New York, Dr. J. Mark Erickson, Department of Geology, 
St. Lawrence University, and Dr. Richard H. Lindemann, 
Department of Geology, Skidmore College, accompanied us in 
the field. Dr. Ed Landing, State Paleontologist allowed access 
to specimens in his charge; Mr. Charles ver Straaten arranged 
for us to photograph a displayed slab in advance of the opening 
of the New York State Museum, Albany, and materially 
assisted with assembling heavy slabs in the research collec?
tions. Finally, at the American Museum of Natural History, 
New York, Mr. Sidney Horenstein located a slab in a basement 
storeroom, which revealed significant data. 
Mr. R. Eng, formerly of the Museum of Comparative 
Zoology, Harvard University, and Dr. M. Nitecki, Field 
Museum of Natural History, Chicago, aided Fedonkin, as did 
Dr. E.S. Belt assist Yochelson at the Pratt Museum of Natural 
History. Dr. Bruce R. Erickson, The Science Museum of 
Minnesota, St. Paul, in 1989 allowed Yochelson access to 
specimens he had collected; further, he provided an unpub?
lished sketch of these trails as they were on the outcrop, several 
photographs, and a plaster cast. At a late stage in this study, Dr. 
A.C Spreng, University of Missouri-Rolla, kindly supplied a 
photograph of a slab from that state and Dr. David W 
Houseknecht, University of Missouri-Columbia, supplied 
unpublished information on the Lamotte Sandstone. In 1991, 
Mr. Robert Pody, Harrisburg, Pennsylvania, donated a speci?
men to the University of Wisconsin, thereby directing attention 
to a new stratigraphically significant locality. 
Many persons responded to inquiries concerning potential 
localities, possible repositories of specimens, general informa?
tion on geology, or provided helpful suggestions. These 
include: Dr. C Galvin, Springfield, Virginia; Dr. D.J. Geist, 
University of Idaho; Dr. R.N. Ginsberg, University of Miami; 
Dr. Yvon Globensky, Quebec Departement de 1'Exploration 
Geologique et Minerale, Montreal; Dr. G.D. Johnson, Dart?
mouth College; Drs. R.M. Linsley and Bruce Selleck, Colgate 
University; Dr. Carl Mendelsohn, Beloit College; Dr. A.K. 
Rindsberg, Alabama Geological Survey, Tuscaloosa; Dr. A. Yu 
Rosanov, Paleontological Institute, Moscow; Dr. W.A.S. 
Sarjeant, University of Saskatoon; Dr. Colin Steam, McGill 
University; and Mr. David Williams, Ontario Department of 
Transportation, Toronto. Mr. Lance Erickson, age 8, made a 
careful pencil rubbing of a slab on Wellesley Island, New York. 
At the National Museum of Natural History, considerable 
photographic assistance was rendered by Mr. Victor Kranz and 
the photographic laboratory of the museum. Mr. Keith Moore, 
U.S. Geological Survey, gave equally valuable help. Ms. Susan 
Socks, U.S. Geological Survey, greatly assisted in word 
processing. An earlier draft of this manuscript was read by Dr. 
NUMBER 74 
Robert H. Dott, Jr., University of Wisconsin-Madison, Dr. 
Rodney M. Feldmann, Kent State University, and Dr. Kristian 
Fauchald, Department of Invertebrate Zoology, National 
Museum of Natural History, and improved by their comments. 
Dr. T.M. Bown, U.S. Geological Survey, Denver, Dr. Bruce 
Runnegar, University of California, Los Angeles, and an 
anonymous critic, further improved the manuscript. 
Ms. Mary Parrish, scientific illustrator in the Department of 
Paleobiology, is to be credited with the reconstruction 
presented herein. She asked insightful questions which forced 
us to be specific where we had generalized. In spite of 
numerous iterations, she remained cheerful, and the results of 
her nimble pen graphically summarize our conclusions. 
Historical Account 
More than a century ago, Sir William Logan (1860) 
described a large and striking trackway that was found at Perth, 
Ontario, by Dr. James Wilson, a medical doctor and important 
local geologist-naturalist. Logan named it Climactichnites 
Wilsoni after its discoverer (capitalization of patronyms was 
then the accepted practice in nomenclature); the generic name 
refers to its similarity in appearance to a rope ladder. The 
specimens were collected in December 1859 by James 
Richardson, who built a fire in the local quarry to heat the rock 
and then quenched it with snow to crack the rock. Zazlow 
(1975:73) discusses the discovery, which followed by a decade 
the even more dramatic discovery by Logan (1851) of 
Protichnites in the Potsdam Sandstone. This is another 
enigmatic form, but one more readily interpreted as the 
trackway of a multi-legged organism striding over unconsoli?
dated sand. 
At the time the above two fossils were named, they were 
virtually the only organic remains known from the Potsdam 
Sandstone. They were also thought to be nearly the oldest 
fossils in the world. In the geologic understanding of the time, 
the Potsdam Sandstone was essentially the first geologic 
formation above the ancient basement rocks of the "Primary" in 
North America, and it was stratigraphically below the highly 
fossiliferous "Silurian." The relationship of the Potsdam 
Sandstone to the Cambrian System, named by Sedgwick from 
north Wales, was not yet evident, and the correlation of this 
sandstone to the Primordial Fauna of Barrande, described from 
Bohemia, was only just being established. The Potsdam 
Sandstone, named from Potsdam, New York, was the first 
stratigraphic name used by the New York State Natural History 
Survey. 
A lifelong bachelor, Logan lived in the building of the 
Geological Survey of Canada. After describing his living 
arrangements, Bell (1907:6) wrote: 
Such was the room in which Logan worked, but about 1860 a new feature was 
introduced in the shape of an immense slab of sandstone which entirely covered 
the wall on one side. This slab was from Perth in Upper Canada and was 
traversed by crustacean tracks called Climactichnites Wilsoni. Every morning 
Sir William gazed on this slab with fond admiration, first with one eye and then 
with the other, as he held his towel and dried his face with alternate hands. 
Logan was an astute observer, both as a geologist and in his 
sole effort as a paleontologist. In his 1860 publication, he noted 
the crenulated margin of the lateral ridges, the variation in 
shape of bars and furrows between these ridges, and the local 
presence and irregularity of a medial ridge, all key features for 
interpretation. Five drawings, clearly illustrating these features, 
accompanied the description and discussion (Figure 1). 
Because of the remarkable nature of this fossil and its geologic 
occurrence, Logan's original report was republished in the 
American Journal of Science the following year (Logan, 1861). 
Hall (1889) again republished Logan's account, unchanged 
except for combining Logan's five figures onto one plate. 
Four years time after the type material was collected, plaster 
casts were made of portions of slabs and sent to Professor 
Edward Hitchcock of Amherst College. These unfigured casts 
are in the collection of the Pratt Museum under numbers 
58/1-58/8, Hitchcock is rightly considered the "father" of 
paleoichnology from his work on footprints in the Connecticut 
River valley Mesozoic. Unfortunately no correspondence 
between Logan and Hitchcock can be located which bears on 
this scientific exchange. Hitchcock died in 1864 before he 
could present an opinion as to the formation of the trail. 
From the time of its first description, Climactichnites 
engendered speculation as to the nature of the elusive 
trace-making animal. Even its nature as the trail of an animal 
was questioned by Chapman (1877), who considered it a 
fucoid. In an extent of the geographic range of the genus, Todd 
(1882) described specimens from New Lisbon, Wisconsin, 
which he named Climactichnites Youngi, again a patronym 
after the discoverer, Reverend A.A. Young, and Todd 
provisionally suggested yet another name, C. Fosteri. Repro?
duction of earlier illustrations of the trace fossil appeared in 
several textbooks of the time, though none contributed new 
data. 
The Smithsonian Archives retain letters of a collector, 
Cooper Curtice, whom Walcott sent to Wisconsin. On August 
16, 1884, Curtice reported to Walcott that he had been to New 
Lisbon and contacted Reverend Young. 
Luckily we found Mr. Fish working in his quarry. Together we uncovered a slab 
about 5 ft by 3'/2 ft which showed the tracks admirably. It weights 600-800 
lbs.... There were 3 pieces showing various tracks that are very desirable in the 
sidewalks. We arranged with the owners that these should be replaced by new 
stones and they are to be shipped. Procured a slab a foot square at Camp 
Douglas by gift which in its way is neat, clearly cut and better than anything 
figured or that I have seen yet. It probably teaches more. Rev. Young is 
enthusiastic and generous of time but pastor of a small church. I left just about 
enough money with him to cover expenses. 
This material cannot be traced and may have been discarded in 
the move a quarter of a century later to the "new" National 
Museum. 
In 1888, local quarrying for paving material at Port Henry, 
New York, yielded abundant trails. Hall (1889) persuaded the 
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
Fig. 4, Ono-fifth nat. size. 
Tig. 2, One-flfth nat. slxe. 
Fig. o, Uue-hfUi nat. size. 
Fig. 1, One-thirtieth nat. size. Fig. 8, One-flfth nat. size. 
FIGURE 1.?Copy of the original illustrations of Climactichnites wilsoni from Logan (1860), rearranged in order 
but bearing his captions. When compared to the original, illustrated in Figure 18, Logan's figure 1 is reversed. The 
other four may also be drawn as positives, rather than sole markings, but this point is not entirely clear. 
town council to send part of their new sidewalk to the New 
York State Museum at Albany in return for comparable 
non-fossiliferous paving blocks. Another very large slab from 
the same area, probably nearly half a ton in weight, is in the 
Milwaukee Public Museum; its history is unknown. 
Just after the turn of the century, a large assemblage of 
Climactichnites trails was found at Mooers, in northern New 
York. Woodworth (1903) in his account of this discovery and 
interpretation of the fossils described an important new feature 
of morphology, an oval-shaped impression at one end of some 
of the trails, plus a few of these impressions separate from any 
trails. Clarke (1905) published a sketch of the outcrop showing 
the distribution of trails and oval impressions, but did not 
discuss them in any detail, confining his remarks to the efforts 
made to quarry a large portion of this outcrop and transport it to 
Albany. Walcott (1912) described another oval impression 
NUMBER 74 
from Wisconsin, one sent to him in 1886 by Reverend Young 
who had discovered the material described by Todd. So far as 
we know, receipt of this oval impression and Walcott's 
collecting at Beauharnois, Quebec, the same year were 
coincidental. 
In a masterful paper, Burling (1917) provided careful 
description and interpretation of Climactichnites. He proposed 
that the animal moved away from the oval impression, not 
towards it as had been suggested by Woodworth. Clark and 
Usher (1948) sketched trails that crossed over themselves and 
confirmed the direction of movement which had been inferred 
by Burling. Finally, Summerson (1951) briefly noted the 
occurrence of the fossil in Missouri and documented this with 
a sketch. That material was compared with a slab of 
Climactichnites from the "Potsdam Sandstone," provenance 
unknown, which was outside of Orton Hall, Ohio State 
University, but was subsequently stolen (Dr. S. Bergstrom, oral 
communication, 1991). 
In part because of the large size of the fossils, there has been 
a dearth of photographic illustrations. For the first five decades 
that this fossil was known, most information was conveyed by 
sketches, and these at a greatly reduced size. Walcott (1912) 
and, to a lesser extent, Burling (1917) did use photographs to 
supplement discussion. Burling photographed two of the oval 
impressions on a plaster cast, and Abel (1935) provided the 
only photograph heretofore of an actual specimen of the oval 
impressions from Mooers; both illustrations were at a greatly 
reduced size. Photographs of trails on the outcrop were not 
published until quite recently (Globensky, 1987). Dawson 
(1890) published a photograph of a slab, lacking in some 
details because of the prevailing methods of reproduction. A 
hundred years later, a clear illustration of this same slab was 
published (Steam and Carroll, 1989, fig. 20-2). 
As a consequence of the limited number and small size of 
illustrations, the great amount of individual variation and many 
of the details of trail formation were not recognized, even 
though these points were indicated in the original sketches of 
Logan (1860). We judge that the illustrations provided herein 
are the single most significant aspect of our effort. For most 
illustrations, all or part of a scale 15 cm long is included; in a 
few, the photographic scale is in both centimeters and inches 
marked by alternating black and white intervals. 
The only reference we have been able to find to a species of 
Climactichnites outside of North America is that of C. mathieui 
Sun (1924:16), named from the Lower Cambrian Manto Shale 
of north China. This trail, if it is a trail, is about half the width 
of the smallest Climactichnites we have observed. Only a short 
length is preserved which shows a prominent V, but we see no 
indication of lateral ridges. In the absence of that important 
morphological feature, we remove this species from the genus. 
Because of the lack of detail presented in the single illustration, 
we are unable to reassign the species and will not consider it 
further in our discussion. 
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FIGURE 2.?Outline map of Wisconsin, showing localities mentioned in the 
text. (1) Chippewa Falls; (2) Eau Claire; (3) Black River Falls; (4) New Lisbon; 
(5) Stevens Point; (6) Mauston. 
Geographic Distribution 
In many sequences, body fossils are more common than 
trace fossils, for bedding plane surfaces are often required to 
expose horizontal traces. In dealing with Climactichnites, an 
unusually large horizontal trail, we have been impressed with 
how much discovery of the fossil depends on the presence of a 
large bedding plane surface. Exposures of such do occur 
naturally, but in platform regions in northern climates where 
soil is present, they are far less common than are vertical 
exposures. We have been unable to find any indication of 
Climactichnites in any of the vertical exposures we examined, 
including the walls of quarries known to have yielded these 
fossils. Collection of Climactichnites has been greatly influ?
enced by artificial exposures. Thus, the type localities for the 
named species are tiny, abandoned quarries from which stone 
for local use was obtained a century or more ago. To discover 
these traces, a quarry must not only be opened for flagstone, but 
its operation must intersect the proper layer, and the material 
exposed must come to the attention of an interested person who 
has the resources for large-scale collecting. Viewed from this 
aspect, it is surprising that so many localities for Climactich?
nites exist and so many specimens are in museums. 
Climactichnites is known in Wisconsin from six general 
areas (Figure 2); localities numbered 1-6 are used in the text 
and refer to this figure. Dr. J.L. Hoff reported to us an 
occurrence in the Irvine Zoological Park at Chippewa Falls (1). 
With Dr. Hoff, we investigated at least a dozen locations along 
a kilometer of the Chippewa River in Eau Claire (2), each of 
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 3.?Outcrop of cross-bedded Mount Simon Sandstone, exposed at low water level, on the west bank of 
the Chippewa River, Eau Clair, Wisconsin (2). The wide trail was made by a Climactichnites moving toward the 
lower right and crossing another trail at right angles. In the upper left, another trail is also at right angles, but is 
on a layer about 1 cm higher in the section. Scale is indicated by a 10 cm ruler. 
which shows several trails when the water level is low; 
specimens are most common on the west bank (Figure 3), but 
are present on both sides of the river. Near Black River Falls (3) 
two separate occurrences are known. Dr. R.H. Dott, Jr. has 
shown us photographs of a large trail along the Halls Creek 
tributary of the Black River. In 1976, Dr. B.R. Erickson 
collected Climactichnites from just below Polly Falls on the 
Robinson Creek tributary; this material is now at the Science 
Museum of Minnesota. 
The type locality for C. youngi is "two quarries located near 
the Lemonweir River. They are about four miles north of the 
village of New Lisbon" (Todd, 1882:276). We were able to 
locate one obvious abandoned quarry and another small former 
operation about six kilometers from New Lisbon (4) in the 
SWV4, NEV4, Sec. 19, T. 17 N, R. 3 E, Juneau County, but both 
are overgrown and no bedrock is exposed. At the Northern 
Stone Company quarry, about five kilometers northeast of 
Stevens Point, Wisconsin, in the NE'A, NE'A, Sec. 34, T. 26 N, 
R. 8 E, Marathon County (5), Mr. W. Nemke showed us a large 
quarry surface containing these fossils (Figure 4). Another 
layer about 2 m higher in the section has also yielded 
Climactichnites, but large surfaces of this layer were no longer 
available. 
Finally, near Mauston (6) two occurrences are known. In 
field notes written in 1927, Gilbert Raasch reported a quarry 
surface in the NE'A, NE'A, Sec. 16, T. 13 N, R. 4 E, Juneau 
County, which was covered with Climactichnites. This locality 
is now overgrown and nothing can be observed. However, in 
1991, specimens were found by Mr. R. Pody in a road cut on 
the east side of Country Road K, near the north line of Section 
31, in the NE'A, NW'A, Sec. 6, T. 14 N, R. 4 E, Juneau County. 
As noted above, Climactichnites has been reported from 
Missouri by Summerson (1951:533). "It is in a small highway 
cut on the north side of Missouri State Highway 70, about 7 
miles west of Fredericktown (NE NW SE, sec. 8, T. 33 N. R. 6 
E.)" (Figure 5). No other occurrences have been reported in the 
NUMBER 74 
FIGURE 4.?A small portion of the working floor, as it was in 1990, in the Northern Stone Company quarry near 
Stevens Point, Wisconsin (5). Obscure, but numerous, narrow trails of Climactichnites occur in various 
orientations throughout the entire field of view. Scale is indicated by a 10 cm ruler. 
literature or are known to geologists we have consulted that are 
working in the state. 
Figure 6 summarizes occurrences in southern Canada and 
New York; localities numbered 7-14 are used in the text and 
refer to this figure. In Ontario, Climactichnites is known from 
two widely separated localities. According to Dr. G.M. 
Narbonne, a small quarry about 1 km northeast of the village of 
Battersea (7), some 25 km north of Kingston, produced two 
slabs now in the possession of Queen's University (Yochelson 
and Fedonkin, 1991). At Perth (8), the precise type locality, in 
Mr. Glyn's quarry "about a mile from the town..." as it existed 
in 1859, cannot be located with any certainty and might now be 
covered by buildings. A geologic map of the area (Wilson and 
Dugas, 1961) noted reports of this fossil in Concession III, Lot 
6. Through the assistance of Mr. D. McNicol, we were able to 
locate a small long-abandoned quarry in this area, but did not 
observe any of the fossils of concern. 
Globensky (1987:4, pi. 1) reported and illustrated several 
large trails of Climactichnites on outcrops about 45 km 
west-northwest of Montreal, Quebec, approximately 2 km 
north from the village of St. Hermas (9) (Figure 7). We were 
able to examine those specimens, and found another nearby 
bedding plane, no more than a meter different in stratigraphic 
level, upon which were additional examples; Protichnites is 
also abundant at this locality. As noted above, in 1886, CD. 
Walcott collected a large slab bearing numerous trails from 
"one mile south of Beauharnois" (10) (Frontispiece), about 15 
km southwest of Montreal. No exposures were seen in the 
vicinity of the town and again the locality may have been a 
small local quarry, now lost. About 3 km to the west, a large 
deep quarry at Melocheville (10) at one time had specimens 
exposed on the quarry floor (Clark and Usher, 1948); however, 
the floor is now covered with debris and part of the quarry has 
been refilled with slag from a nearby aluminum reduction 
operation. We have been unable to locate any specimens which 
SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 5.?Photograph of slab of Lamotte Sandstone from seven miles north of Fredericktown, Missouri. This 
slab was sketched by Sumerson (1951), who also noted the presence of Protichnites; these occur just to the left 
of the trail on the lower right of the slab. There are four Climactichnites trails, one at the left and two at the right, 
all crossed by a longer one at right angles formed by an animal moving from right to left. The trail at the far right 
is not well preserved and is best seen near the extreme right of the photograph. Photograph courtesy of Dr. A.C. 
Spreng, University of Missouri-Rolla. Department of Geology and Geophysics collections, number 7283. Scale 
is indicated by a 10 cm ruler. 
might have been collected from this quarry or even any 
photographs of the specimens. 
In New York, at the Minna Anthony Common Nature Center 
on Wellesley Island (11), near Alexandria Bay, a slab bearing 
Climactichnites is part of a "geological wall" just outside the 
building. Apparently it was collected from a site on the island 
but, according to Dr. J.M. Erickson, a small local quarry which 
might have yielded it is overgrown and has no outcrop. At 
Mooers (12), also in extreme northern New York, a large part 
of a bedding plane surface was obtained as a result of two 
months quarrying (Clarke, 1905). No outcrop is now exposed 
and only a single rotted railway tie marks the spot. In contrast, 
we were able to examine a large number of specimens exposed 
on one bedding plane at Au Sable Chasm (13), Keeseville, a 
locality reported by Van Ingen (1902) (Figure 8). The locality 
is east of the steel bridge along the old state highway and just 
below the dam constructed on the site of Alice Falls in the Au 
Sable River. Finally, at Port Henry (14), where Hall (1889:25) 
convinced the local authorities to donate their sidewalk, we 
were unable to find any significant outcrops of sandstone. 
According to residents, there are no local flagstone quarries in 
operation. The limited number of outcrops of the Potsdam 
Sandstone and the current lack of Climactichnites specimens in 
any of the outcrops in this area and at Mooers was 
independently confirmed by Dr. R.H. Lindemann. Dr. B. 
Selleck also has not observed this fossil in situ at Port Henry. 
To summarize, Climactichnites is known from northeastern 
and north-central North America. It is widely scattered through 
outcrops, which if connected would indicate its distribution 
through an area of several thousands of square kilometers. To 
the best of our knowledge, the fossil is unknown from other 
localities in North America or elsewhere, and this trace-making 
animal could have been endemic to this area. All known 
occurrences of Climactichnites are in sandstones, a point 
considered in more detail below. 
NUMBER 74 
Stratigraphic Range 
Climactichnites occurs in rocks that contain virtually no 
body fossils, so it is therefore difficult to obtain any 
independent data as to its range. Characteristically, the units in 
which it is present are dated by trilobites, and occasionally 
other forms, that occur in the next overlying stratigraphic unit. 
In most regions, the base of the sandstone bearing Climactich?
nites is marked by a profound unconformity with the 
underlying Precambrian. Many years ago, Walcott elaborated 
the concept of a flooding of the North American continent 
during the Cambrian, with Upper Cambrian deposits wide?
spread on the cratonic platform, and older beds restricted to 
continent marginal zones. From this evidence one may assume 
that there is no basis for suggesting that rocks yielding 
Climactichnites are Middle Cambrian or older, though such an 
unlikely prospect cannot be completely refuted. 
The Late Cambrian in North America is divided into three 
stages, Dresbachian, Franconian, and Trempeleauan. Resser 
(1933) listed the Mount Simon Formation of Wisconsin as the 
basal unit of the standard Upper Cambrian section, but without 
any faunal zone indicated for this interval, for it contains no 
trilobite remains. In a subsequent correlation table, Resser 
(1938:20) denoted a zone of Climactichnites as the basal 
interval of the Dresbachian, but without any explanation. 
Raasch (1939:87) briefly mentions a Climactichnites fauna. In 
a later correlation chart (Howell et al., 1940), a Climactichnites 
zone was not mentioned and the Cedaria Zone appeared as 
basal Dresbachian. 
In many of the earlier stratigraphic studies in Wisconsin the 
Mount Simon Formation below and Eau Claire Formation 
above were included in Dresbachian time. More recently, the 
Eau Claire has been restricted and the former upper part has 
been named the Wonewoc Formation; the Wonewoc is divided 
into the thick Galesville Sandstone Member and the thin 
Ironton Member. It is now recognized that beds once 
interpreted as simple sheet sands in fact represent a complex of 
intertonguing units deposited in environments ranging from 
fully terrestrial to fully marine. 
Of the occurrences in Wisconsin, localities 1 through 3 are 
definitely in the lower part of the Mount Simon Sandstone. The 
locality at the Northern Stone Company quarry (5) is less 
readily assigned because of the paucity of outcrops in the area, 
but investigations by Dr. R.H. Dott, Jr., in 1991 indicate that 
almost certainly the material quarried is from the Mount Simon 
Formation. This interpretation is supported by information 
from a local well that suggests the occurrence may be low in 
that unit. Along the Chippewa River (2), all occurrences appear 
to be confined to a single stratigraphic unit a few meters thick 
(Dr. J.L. Hoff, oral communication, 1990); the overlying beds 
contain Skolithos, Arenicolites, and Rusophycus. The two 
occurrences along the Black River (3) may be quite low in the 
formation and extremely close stratigraphically (Dr. R.H. Dott, 
Jr., oral communication, 1990). 
However, the new locality, found in 1991 by Mr. R. Pody, 5 
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FIGURE 6.?Outline map of parts of Ontario, Quebec, and New York, showing 
localities mentioned in the text. (7) Battersea, Ontario; (8) Perth, Ontario; (9) 
St. Hermas, Quebec; (10) Beauharnois-Melocheville, Quebec; (11) Wellesley 
Island, New York; (12) Mooers, New York; (13) Keeseville, New York; (14) 
Port Henry, New York. 
mi south of Mauston (6), is younger, though still within the 
Dresbachian. Specimens occur high in the Galesville Member 
of the Wonewoc Formation, a non-feldspathic, pure quartz 
sandstone. The Galesville is interpreted as a sedimentological 
complex, locally having cross-bedded terrestrial dunes in the 
lower part, lower-angle cross bedding in the medial portion, 
and more planar bedding above. The Climactichnites speci?
mens occur low in the planar-bedded unit, which from 
sedimentological evidence is judged to be a beach deposit. 
About three meters above the bed bearing the trails, the thin 
Ironton Member yields numerous tubes of Skolithos; it is 
interpreted as a littoral marine bed deposited during transgres?
sion of the Wonewoc sea (Dott et al., 1986). 
The beds in this part of Wisconsin are nearly flat lying. 
Based on the regional dip of less than one degree, it is probable 
that the specimens collected from New Lisbon (5) are from the 
Galesville Member of the Wonewoc Formation, rather than 
from the Mount Simon; because of large areas of alluvial cover 
between New Lisbon and Mauston, this stratigraphic assign?
ment cannot be proven. The quarry floor observed by Raasch 
near Mauston (6) is less readily dated but could also be in the 
Galesville, based on its elevation. 
The new discovery at Mauston (6) makes it obvious that 
Climactichnites is not confined to a single instant of time, but 
does have a stratigraphic range through most of the type 
Dresbachian. Approximately 100 m of sediment, predomi?
nately sandstone, was deposited in Wisconsin from low in the 
Mount Simon to high in the Galesville. 
The sole occurrence in Missouri is in the Lamotte Sandstone 
10 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 7.?A bedding plane of the Cairnside Formation at St. Hermas, Quebec (9), bearing two very wide trails 
of Climactichnites. The longer trail, in the backround, formed by an animal moving from right to left, shows a 
medial marking, which is variable in position relative to the bounding lateral ridges. The trail at the left, formed 
by an animal moving toward the top of the photograph, shows no such feature. The white blotches at the upper 
left are plaster of Paris left by an unknown investigator. Scale is indicated by a 15 cm ruler. 
(Summerson, 1951), a unit traditionally considered Dresba?
chian and correlated to the Mount Simon of Wisconsin. The 
Lamotte varies greatly in thickness, for locally it fills valleys 
between buried hills. Houseknecht (1975) found an additional 
slab bearing Climactichnites as float at the site of the original 
report, SW'A, NW'A, SE'/4, Sec. 5, T. 33 N, R. 6 E. The total 
thickness of the section exposed in a road cut at this locality is 
only about 10 m and Dr. W Houseknecht is convinced that the 
fossil occurs very high in the Lamotte. The Bonneterre 
Dolomite, which overlies the Lamotte Sandstone, has yielded 
the Dresbachian Cedaria fauna. 
In New York, the earliest biostratigraphie information that 
we are aware of concerning Climactichnites is that of Van 
Ingen (1902). He made a detailed study of the Au Sable Chasm 
section at Keeseville (12), and noted that no organic remains 
were found in the lower part of the formation. "The middle part 
of the formation has afforded only the Climactichnites tracks at 
the Birmingham bridge, and numerous irregular, unidentified 
worm borings and trails" (Van Ingen, 1902:544). Van Ingen 
developed a zonal scheme based on the few body fossils and 
other traces found; several species of inarticulate brachiopods 
and the trilobites Conocephalites verrucosa Whitfield and 
Ptychoparia minuta Conrad were reported by him, some 
distance above the Climactichnites bed. Fisher (1968:16) 
mapped the region in detail and reported Climactichnites in the 
unnamed medial member of the Potsdam Sandstone. The 
overlying Keeseville Member is dated by him as Dresbachian 
because of the occurrences of the earlier named trilobites. Many 
bedding planes are exposed below the dam and in Au Sable 
Chasm itself, but except for this single layer no other 
occurrence of Climactichnites are known. Protichnites occurs 
with Climactichnites and on bedding planes a few meters below 
the Climactichnites layer. 
The composite section in and around Keeseville may be 
divided into several sedimentological cycles (Dr. B. Selleck, 
oral and written communications, 1990). Older non-marine 
sandstones are followed by Dresbachian subtidal deposits, 
representing a rapid transgression. These are followed by a 
NUMBER 74 11 
FIGURE 8.?A bedding plane of Potsdam Sandstone in the temporarily dry bed of the Au Sable River just below 
the dam at Keeseville, New York (13). The surface is almost totally obscured, or bioturbated, by wide trails of 
Climactichnites, but in the lower right center a pattern of low amplitude asymmetric ripple marks can be observed. 
Scale is indicated by a 15 cm ruler. 
regressive phase of peritidal deposits in which Climactichnites 
occurs. Correlation by Selleck of these cycles to Port Henry 
(13), suggests that the material obtained there a century ago 
might be at essentially the same stratigraphic interval as at 
Keeseville. In the absence of any specimens precisely located, 
this is the best estimate of stratigraphic position that can be 
made. 
In southern Ontario, traditional usage of Potsdam Sandstone 
has been refined, and the Potsdam Group is now divided into 
the Covey Hill Formation below, and the Nepean Sandstone 
above. The Covey Hill is confined to downdropped fault blocks 
and its relationship to the Nepean is not known in detail. In 
more general terms, the Nepean Formation thins northward. At 
its type locality, just to the south of Ottawa, it is of Arenigian 
age, based on conodonts (Brand and Rust, 1977). No other 
precise dates are available for this sandstone sequence 
elsewhere in the province. To some extent, the late Early 
Ordovician date at the top of the Nepean has influenced views 
on the age of the entire group. 
In southern Quebec, the interval of sandstone deposition is 
generally thicker than in Ontario and is divided into the Covey 
Hill Formation below, a unit about 500 m thick, and the 150 m 
thick Cairnside Formation. Globensky (1987:46) reported 
Climactichnites in the Covey Hill, but reexamination of the 
outcrop at St. Hermas has convinced him that because of both 
the pronounced cross-bedding and the pink hue, produced by a 
high feldspar content of the sandstone, these fossils occur low 
in the Cairnside. (Dr. Y Globensky, oral communication, 
1990). He also noted that at a former locality near Montreal, no 
longer available, a tongue of feldspathic sandstone of the 
Cairnside occurs within the Covey Hill and this contained 
Climactichnites (Dr. Y. Globensky, written communication, 
1990). 
In discussing the problem of a fossil restricted to a particular 
facies, it is necessary to differentiate, if possible, the issues of 
habitation from those of preservation. In a general sense, the 
history of the Late Cambrian in eastern and central North 
America is that of a broad, intertidal and subtidal sand flat 
gradually encroaching on the source area by relative rise in sea 
level, so that by later Cambrian time the influx of siliceous 
12 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
particles was checked by the submergence of the source area. 
Deposition of carbonates then became the norm. If one accepts 
an interval of about 30 million years for the Late Cambrian, the 
Dresbachian interval was probably 5-10 million years in 
length; even during that relatively short time, generally similar 
conditions must have existed in various parts of this vast sheet 
of sand. 
Both Drs. R.H. Dott, Jr., and R. Dalrymple independently 
noted that the Mount Simon in Wisconsin and the lower part of 
the Covey Hill, as used near Kingston, Ontario, differ 
principally from sandstone beds higher in the section by 
containing significantly greater amounts of feldspar. However, 
the presence of feldspar is associated with small grain size, not 
with age. The new occurrence in the Galesville Member of the 
Wonewoc Formation indicates that Climactichnites occurs in 
non-feldspathic beds. This is a facies-related fossil, as indeed 
all are to a greater or lesser extent. We suggest that the animal 
preferred a fine-sand beach over one of coarser sand, and that is 
the reason for its more common occurrence in feldspathic-rich 
units. 
There is no theoretical reason why any particular fossil 
necessarily should be either long-ranging or appear and 
disappear almost simultaneously. Two alternative possibilities 
therefore exist for stratigraphic interpretation. Climactichnites 
could be closely tied to a particular facies and therefore time 
transgressive through the Late Cambrian and perhaps into the 
early Early Ordovician. Alternatively, it may have been such a 
specialized form that it existed for only a short interval. 
Although there is little basis for choice between these two 
alternatives, the limited stratigraphic evidence suggests to us 
that, even with the discovery of a younger occurrence, 
Climactichnites may be quite restricted in a time sense and 
further restricted to one facies within the transgressive 
sandstone. Clearly the Cambrian sea did not transgress from 
New York to Wisconsin instantaneously, yet the overlying 
faunas in both regions are of Dresbachian age. The same age 
relations exist in transgression from Missouri northward to 
Wisconsin. 
In addition, if our interpretation and reconstruction of 
Climactichnites is valid, it may have been an "experimental" 
form and perhaps, therefore, less likely to have a long vertical 
range; its endemism adds a slight bit of additional support to 
this view. 
Even though negative evidence can be destroyed in an 
instant, we know of no reports of Climactichnites in overlying 
Cambrian beds which can be dated as younger than Dresba?
chian. We judge this absence to be consistent with the view that 
Climactichnites was more restricted by time than by facies. If 
the interpretation of a restricted time interval is correct, this 
fossil may have utility as an indicator of age in beds that are 
otherwise nearly barren of fossils. One consequence of this 
suggestion is germane to southern Ontario. Assuming the type 
locality for Climactichnites at Perth (8) is Dresbachian and the 
Nepean Sandstone at Ottawa is Arenigian, a major discon-
formity exists in the section. 
Environmental Setting 
At the field localities where Climactichnites has been 
observed, the Potsdam Sandstone and its stratigraphic equiva?
lents show depositional features of an environment varying 
from exceedingly shallow water to temporarily subaerial, in 
effect from the high tidal zone to the peritidal zone. The issue 
of the height of tides in the past is a difficult one to approach, 
but because of the damping effect of a vast shelf area, it seems 
unlikely that tides exceeded more than one to two meters and 
probably were closer to the former (Dr. R.N. Ginsberg, written 
communication, 1990). If the moon was somewhat closer to the 
earth during Cambrian times, tidal amplitude and frequency 
would have increased, and, as a consequence, more fine 
clay-sized particles would have been winnowed out from the 
sand. 
The overall geographic setting for Climactichnites could 
well have been similar to that of the present North Sea coast of 
Germany at extremely low tide, but with sediments predomi?
nately of fine sand size rather than clay size. The concept of 
tidal movement alternately covering and exposing such large 
flats has been used freely in the literature to indicate change in 
water level, and is useful in interpreting Cambrian sandstones. 
For example, Dreise, Byers, and Dott (1981) divided the Mount 
Simon into three lithofacies; Climactichnites occurs within 
what is generalized as "shallow subtidal deposition in a 
relatively high-energy regime." As a partial alternative to 
reliance on tidal mechanisms to explain some sedimentological 
features, Ginsberg (in Dott and Byers, 1981:345) has suggested 
that strong winds at irregular intervals might have drained off 
water, which was only a few meters deep in an epicontinental 
sea, and that desiccation cracks could have formed during such 
an event. 
A spurious relationship between width of the trails and 
energy level originally confused us. At the Northern Stone 
Company quarry (5), the present working surface is covered by 
abundant trails 4-6 cm in width, smaller than average (Figure 
4). The relatively fine size of the quartz grains and the absence 
of pronounced ripples was interpreted to indicate quiet water 
conditions. About a meter higher in the section, a thicker-
bedded and very slightly coarser sandstone bed carries trails 
8-10 cm in width. Adjacent to both levels, but not directly 
associated with either, are asymmetrical ripple-marked sand?
stone beds without any preferred orientation of these current 
ripples among the layers. One of these layers is furrowed by 
worm-like trails cutting across the ripples (Figure 9). Speci?
mens of Climactichnites from this locality in the Milwaukee 
Public Museum collected some years earlier show still slightly 
wider trails on ripple-marked slabs, the ripples again being 
slightly higher in amplitude than any we observed on the 
outcrop and nearly symmetrical in cross-section. 
FIGURE 9.?Ripple-marked sandstone in the Northern Stone Company quarry, Wisconsin (5), about two meters 
above the working floor. Gordia-Yike trails cut through the asymmetrical interference ripples. Scale is indicated 
by a 10 cm ruler. 
However, further observations confirmed that there is no 
obvious correlation between grain size, ripple height, or other 
potential indicators of energy level in the epicontinental sea, 
and the width of Climactichnites trails. Along the Chippewa 
River at Eau Claire, Wisconsin (2), trails ranging from 15-20 
cm in width occur in a cross-bedded sandstone. This unit shows 
bimodal direction of cross bedding and is interpreted as a tidal 
deposit (Dr. J.L. Hoff, oral communication, 1990); Climactich?
nites crosses the low ridges and swales of the bedding planes. 
In contrast, trails from Perth, Ontario (8), are as wide as those 
from Eau Claire, yet occur in fine-grained sandstone; the 
paucity of ripple marks suggests quiet water. At Perth, only 
low-angle "herring-bone" cross-bedding in a bed 3 cm thick 
was seen on the wall of a local quarry, and there was no 
indication of any pronounced large set cross-bedding. 
Specimens from Port Henry, New York (14), are associated 
with relatively sharp-crested interference ripples (Figure 10), 
whereas those from Perth, Ontario (8) (Figure 11), St. Hermas, 
Quebec (9), and Mooers, New York (12), are on smooth 
bedding planes. At Keeseville, New York (13), and St. Hermas, 
(9), one can observe that the bedding plane is not flat, but 
shows broad, shallow swales, like those of a modem tidal flat. 
The type slab from Perth in Ottawa, and those from Mooers in 
the New York State Museum and the Pratt Museum are large 
enough to further confirm a slight irregularity of the surface 
over which Climactichnites moved. 
In Missouri, "Near the close of Lamotte deposition the area 
was inundated by an Upper Cambrian sea, resulting in 
contemporaneous deposition of alluvial and shallow marine 
sediments" (Houseknecht and Ethridge, 1978:585). More 
14 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
specifically, Climactichnites occurs above a fluvial channel 
deposit, indicating that "the tracks were probably formed in the 
washover or sandstone flat environment of the transgressive 
sequence" (Houseknecht, 1975:75). Along the Halls Creek 
tributary of the Black River in Wisconsin (3), Climactichnites 
occurs in the Mount Simon Sandstone 3 m above the base of the 
Precambrian in an outcrop "dominated by channel and 
low-angle truncation surfaces paved with claystone interclasts, 
large-scale tabular sets of cross-strata, and reactivation sur?
faces" (Driese, Byers, and Dott, 1981:371). We are not aware of 
any other localities where the beds containing this fossil have 
been studied in detail by sedimentologists. 
An indication of drying conditions associated with Climacti?
chnites is provided by desiccation cracks which we found in 
float pieces in the local quarry at Perth (8). More direct 
evidence is provided by the outcrop at St. Hermas (9) where 
desiccation cracks cut across a trail of Climactichnites. Another 
line of evidence is provided by sand holes, formed by air 
escaping from the sediment (Emery, 1945). Slabs from 
Robinson Creek along the Black River in Wisconsin (3) show 
a large number of such pits and craters (Figure 12). These 
structures were observed at St. Hermas (9) (Figure 13), and on 
the type slab from Perth (8) (Figure 14); they were seen at one 
level in Battersea quarry (7). These air hole structures penetrate 
the trails and developed subsequent to them in the St. Hermas, 
Perth, and Robinson Creek examples. Less well developed pits 
and craters have been observed within trails from other 
localities, but are more difficult to document with photographs. 
Emery and Foster (1948) noted that the relative fluctuation 
of the water table on a beach lags behind the tidal cycle. 
Presumably, waves from an incoming tide of low amplitude 
would break on a subaerial beach and drive air upward to form 
these structures. If the beach gradient was appropriate, there 
might be sufficient time for such air holes to harden before 
being covered; on a modem high-energy Atlantic Ocean beach 
they are ephemeral. Admittedly, considerable argument sur?
rounds the question of whether such pits could also be formed 
by raindrop impressions; in the examples we have observed, 
this seems unlikely. Regardless of whether these holes are 
formed by air escape from below, or water drops from above, 
FIGURE 10.?Sharp-crested asymmetrical interference ripples cut by trails of Climactichnites on a slab of 
Potsdam Sandstone from Port Henry, New York (14). This is the lower surface of the overlying bed?a sole 
marking?so the surface relief is reversed. Scale is indicated by a 15 cm ruler. NYSM unnumbered. 
NUMBER 74 15 
FIGURE 11.?A portion of the type slab from Perth, Ontario (8), temporarily reassembled, showing the smooth 
surface of the sandstone. This is the same orientation as Figure 18 showing the entire surface. This is a sole 
marking, so the surface relief is reversed. Scale is indicated by a 15 cm ruler. GSC 6299. 
16 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 12.?An incomplete Climactichnites trail above and numerous air hole pits and mounds below, on a slab 
of Mount Simon Sandstone from Polly Falls, Black River Falls, Wisconsin (3). Photograph courtesy of Dr. B.R. 
Erickson, Science Museum of Minnesota, St. Paul, Minnesota. Scale in millimeters. SMM-P unnumbered. 
NUMBER 74 17 
they are strong indicators of a surface which was not covered 
with water when they were formed. 
From these observations, we conclude that Climactichnites 
made its trail on subaerial sandflats. During the time it crawled, 
the sand was damp, but not saturated with water, for the trail is 
constructed in large measure of molded sand. When the animal 
moved forward, the trail was exposed to subaerial drying. 
In such a setting, the effect of wind driven waves could have 
been locally profound. As a consequence of a variety of factors, 
including minor changes in water depth, slight irregularities on 
the bottom, differential sorting of the sand grains, changes in 
salinity, and capillary action, we envision an environment in 
which the water content of the sand could vary from spot to 
spot. The rheologic features of the sediment cannot be 
reconstructed from the sandstone matrix, but local changes may 
be inferred from the variation in morphology seen among 
adjacent trails and within a single trail. 
The presence of a relatively large amount of feldspar in most 
outcrops yielding Climactichnites is certain. Odom, Doe, and 
Dott (1976) have documented the much more common 
occurrence of abundant feldspar in older Paleozoic sandstones, 
but particularly its concentration in rocks composed of smaller 
grain size sediment. Grains of feldspar would be larger than 
hydrodynamic equivalents of quartz, but not to any appreciable 
degree. The presence of feldspar, even in abundance, would not 
likely significantly modify the capillary features of a sand 
deposit. Time did not permit any study of composition and 
grain size of sediment and of associated trail width. We can 
therefore only make the generalization that because many 
Climactichnites occur in feldspar-rich sandstones, many of 
these animals probably crawled on fine-grained sand beaches, 
which in turn might indicate quiet water conditions. However, 
these trails do occur in coarser-grained sandstones. 
Classically, the Late Cambrian sheet sands were considered 
as shallow marine beach deposits, but restudy by a generation 
of sedimentologists has shown that a variety of environments 
are represented in these beds. They range from terrestrial, 
through fluvial, to marine. It is readily apparent that our 
FIGURE 13.?A bedding plane of the Cairnside Formation at St. Hermas, Quebec (9). The right half of the view 
shows clearly numerous desiccation cracks, several of which cut a Climactichnites trail further to the right At the 
left are more desiccation cracks and another convoluted trail, shown in more detail in Figure 39. Although they 
are difficult to see, Protichnites tracks are near the center of the field of view. Scale is indicated by a 15 cm ruler. 
18 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 14.?Part of the type slab from Perth, Ontario (8), showing a portion of a trail and numerous air escape 
features. This is a sole marking, so the surface relief is reversed. Scale is indicated by a 15 cm ruler. GSC 6299. 
characterization of the environment is entirely qualitative, 
rather than quantitative. There are many environmental 
variables which we are unable to address, but by almost any 
standards, the changes from submarine to terrestrial posed a 
harsh environment for life. Perhaps the phrase "marginal 
marine" best indicates both the presumed exposure at low tide 
and the quality of life. If Climactichnites crawled on exposed 
sand flats, the daily temperature and ultraviolet radiation from 
the sun would pose major problems. To add one more 
speculation, a possibility for amelioration is that the animal 
crawled at night or during times of low ambient light rather 
than during sunny days. 
Emery (1945:65) also noted the occasional presence of 
cavernous sand below the exposed beach surface. He made the 
suggestion that "tracks made by such an animal walking over 
cavernous sand may be very deep even if the animal be of 
relatively little weight." To the best of our knowledge this 
interesting point has not been pursued, but it is yet another 
variable to consider should a detailed sedimentological study of 
the environment of deposition of Climactichnites be under?
taken. 
Systematic Paleontology 
Phylum Incertae Sedis 
Class, Order, and Family Unknown 
DISCUSSION.?It is the accepted practice among those 
paleontologists concerned primarily with fossils known only 
from their traces not to construct a hierarchical classification. 
As will be developed, we have interpreted enough detail 
concerning the animal to suggest that Climactichnites does not 
fit into any currently known phylum, living or extinct. 
NUMBER 74 19 
Genus Climactichnites Logan, 1860 
TYPE SPECIES.?Climactichnites wilsoni Logan, 1860. 
DISCUSSION.?We judge that the characters of the genus and 
those which distinguish the type species cannot be differenti?
ated. As a consequence, a more detailed description is given 
under the species. 
Climactichnites wilsoni Logan, 1860 
Climactichnites Wilsoni Logan, 1860:279-285; Dawson, 1890:599. 
Climactichnites Fosteri Todd, 1882:280. 
Climactichnites Youngi Todd, 1882:280. 
Climactichnites wilsoni.?Woodworm, 1903:956-966; Clarke, 1905:18-20; 
Walcott, 1912:259-262; Burling, 1917:390-397; Abel, 1935:242-249; 
Clark and Usher, 1948:251-253. 
DIAGNOSIS.?A form known only from an epirelief trail that 
is characteristically preserved as a ribbed band of uniform 
width bounded by a pair of parallel crenulated ridges, and, 
rarely, having an oval impression at one end of the trail. 
DESCRIPTION.?The oval impression is oriented with the 
longer axis along the trail and has the same width as the 
ribbon-like portion of the trail; it is impressed and lies slightly 
below the level of the trail. Commonly, the upper surface of the 
oval impression is smooth, though it may contain a few gentle, 
but irregular longitudinal ridges and depressions. In excep?
tional preservation, closely spaced wrinkles in an arch-like 
configuration, are present. The proximal end of the oval 
impression is connected directly with the ribbon-like trail and 
is seldom distinct. 
The ribbon-like trail is the more characteristically occurring 
portion of the trail and has a peculiar relief consisting of 
regularly alternating depressed furrows and raised bars. In plan 
view the pattern of bars and furrows is variable, even on the 
same trail, though it is approximately bilaterally symmetrical. 
These features contain all variants in general shape from 
straight transverse, through sigmoidal and arch-like, to approx?
imately V-shaped. In the latter pattern, the bars may be 
arranged in a connected V or in an alternating pattern when left 
and right halves are offset en echelon along the axis. 
The cross-sectional profile of the bars is asymmetric, the 
steeper slope being away from the oval impression. In 
exceptional preservation, thin arch-like wrinkles are present 
and most prominent on the gentler slope of the bars. The distal 
end of the bars may be perpendicular, oblique, or sigmoidal 
toward the bounding parallel ridges. Again in exceptional 
preservation, a thickening near the juncture of bar and ridge 
occurs, but this seems to be a highly variable feature. 
The bars and furrows are bounded by two parallel raised 
ridges, more or less hemicircular in cross-section, the bounding 
ridges being particularly prominent in large individuals. 
Commonly, the inner edge of each ridge is nearly straight. The 
outer edge also may be straight, but more characteristically is 
crenulated. There are slight irregularities in the width and depth 
of the crenulations. 
All features of the trail, that is the lateral ridges, the bars and 
furrows, and the oval impressions, have a relatively very 
smooth surface when compared to the adjacent matrix. 
DISCUSSION.?We have confined our synonymy to the 
references which provided new data on morphology, rather 
than those that reproduced earlier illustrations and speculated 
as to the form of the animal making the trail; these are 
discussed elsewhere. The synonym given above is taken in part 
from Walcott (1912:259), the only author to provide such data. 
Interestingly enough, Walcott did not formally use a species 
name in connection with discussion of specimens. He did use 
species names on the illustrations of new material he described, 
and he recognized both C. youngi and C. wilsoni at New 
Lisbon, Wisconsin (4). 
Walcott, like earlier authors, credited the species C. youngi 
to T.C. Chamberlin, but Todd (1882:276) was quite clear that 
in 1879 Chamberlin gave an oral presentation and illustration 
of the material. In the light of this remark, under the 
International Rules of Zoological Nomenclature, Todd did not 
quote directly from a Chamberlin manuscript. Therefore, Todd 
is the author of C. youngi and C. fosteri. Even though Todd 
used both specific names "provisionally," they are still validly 
designated. As noted above, we have formally placed both in 
synonymy under C. wilsoni. 
Although Walcott used both C. youngi and C. wilsoni in his 
figure captions, he gave no reason for differentiating them, and 
wrote "much could be written about the details of these trails, 
but with the reproductions based on photographs and the 
descriptions of the figures the student may draw his own 
conclusions" (Walcott, 1912:261). On the one specimen that he 
differentiated as C. wilsoni (Walcott, 1912, pi. 40: fig. 1), 
Walcott noted "the action of water forming the longitudinal 
furrows." If correctly interpreted, these rill-like marks cutting 
the bars of the trail may be yet another indication of peritidal 
conditions (Figure 15). 
The type lot of C. youngi was approximately half a ton of 
slabs which more than a century ago were stored at Beloit 
College, Beloit, Wisconsin (Todd, 1882:277). The only 
illustration accompanying the description of this species is a cut 
based on a photograph of one of the slabs (Figure 16). 
Unfortunately, no material from this type lot or indeed any 
specimens of Climactichnites remain at Beloit College, nor is 
there any reference to them in departmental records (Dr. C. 
Mendelsohn, written communication, 1990). These slabs were 
not identified at the University of Wisconsin-Madison, or the 
Field Museum of Natural History, Chicago, two repositories 
where they might have been taken by Chamberlin after he left 
Beloit College. It would appear that the type lot of C. youngi 
has been discarded. 
Todd (1882:279) distinguished C. youngi in part because it 
seemed to lack the paired lateral ridges of C. wilsoni. As noted, 
Walcott (1912) identified material lacking such ridges as C. 
20 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
wilsoni. They are also lacking on a portion of a trail associated 
with an oval impression (Walcott, 1912, pi. 38: fig. 1) and low 
and obscure on another portion of a trail (Walcott, 1912, pi. 39: 
fig. 2). On both these latter specimens, the furrows are sharp, 
but bars are absent. We suggest that bars and lateral ridges were 
washed away because there was insufficient time for them to 
harden before water level rose with the incoming tide. 
Chamberlin (1883:133) thanked Reverend Young for the 
half ton of slabs at Beloit and added, "he has also supplied the 
University of Wisconsin and Dartmouth College with speci?
mens." The slab at Madison, Wisconsin, has no locality data, 
but this quotation suggests that it might be from New Lisbon, 
Wisconsin. A slab at Dartmouth College was present but was 
discarded many years ago (Dr. G.D. Johnson, oral communica?
tion, 1990). 
Fortunately, there is another topotype which confirms that C. 
youngi is based on a sedimentological feature. The Pratt 
Museum has a large triangular slab, number 68/1, catalogued as 
being from New Lisbon, Wisconsin. No documentation has 
been found in the college archives for its date or collector, but 
an old photograph shows that this slab was on display in 1904 
and presumably earlier. Because B.K. Emerson of Amherst 
College and T.C. Chamberlin were contemporaries, it is 
plausible to assume that Chamberlin sent this piece to the 
institution having the largest collection of trackways in the 
United States. 
The slab is a coarse-grained iron-rich sandstone ripple-
marked with low, broad, slightly asymmetrical ripples (Figure 
17), crossed by seven trails. The texture and color are strikingly 
different from those features in Walcott's specimen and 
demonstrate that Climactichnites occurred on at least two 
different bedding planes at New Lisbon, not unlike the 
occurrence at the Northern Stone Company quarry (5). None of 
the lateral ridges are crenulated and we attribute this in part to 
larger grain size. Although all the trails show lateral ridges at 
one point or another, one trail changes dramatically from a C. 
-*, 
FIGURE 15.?A specimen, probably from the Galesville Sandstone, from New Lisbon, Wisconsin (4), illustrated 
by Walcott (1912, pi. 40: fig. 1) as C. wilsoni. The specimen is a sole marking so the surface relief is reversed. 
No lateral ndges are present and the rill-like markings cut across the bars. Scale is indicated by a 15 cm ruler. 
USNM 58547. 
NUMBER 74 21 
FIGURE 16.?Original illustration of C. youngi and, at the bottom of the 
illustration, C. fosteri, reproduced from Todd (1882:277). The caption reads 
"Plate 1?Fossil tracks on Potsdam Sandstone (From photograph)." 
wilsoni to a C. youngi morphology along its length. We are thus 
satisfied that the presence or absence of the lateral ridges might 
be explained as either a sedimentological feature or as a feature 
of individual variation on the part of the animal, or both. 
Todd (1882) also mentioned the presence of fine longitudi?
nal markings as a point of differentiation for C. youngi, though 
these are not observable in his illustration. Presumably, such 
markings are like those illustrated by Walcott and reillustrated 
herein. The reason for preservation of such fine detail in one 
sandstone layer at New Lisbon, Wisconsin, is unknown, but 
there is no reason to assume that these features were limited to 
the organism which lived at that one locality. We attribute the 
arch-like lines to unique conditions of preservation rather than 
to unique morphology. 
A narrow trail was tentatively designated by Todd as C. 
fosteri because it had straight bars, rather than V-shaped ones 
along part of its length. This name was mentioned and 
reillustrated by Chamberlin (1883:132) and Dana (1895:479), 
but neither added new data. As will be seen on many of our 
illustrations, the angle of inclination of the bars to the lateral 
ridges may change dramatically through the preserved length of 
a trail. We are satisfied that only C. wilsoni has any biological 
meaning. 
As to the type lot of C. wilsoni itself, a number of slabs of the 
sole surface of the overlying rock, totaling about 8 square 
meters, were collected in 1859. They were assembled in plaster 
and used as a wall display. When the Geological Survey of 
Canada collections were being removed to Ottawa, "it fell with 
a crash, shattering the plaster casts round the specimen into 
fragments and breaking some of the sandstone" (Weston, 
1899:135). It was reassembled and hung on the wall of the 
National Museum of Natural Sciences in Ottawa. After removal 
from that institution (Figure 18), the plaster backing again 
broke. The various pieces are now in the type collection of the 
Geological Survey of Canada and numbered GSC 6299. To 
avoid any future uncertainty, we designate the longest trail seen 
on Figure 18 as the lectotype and reproduce part of it (Figure 
19) for purposes of identification. The other trails of C. wilsoni 
on this slab have the status of paralectotypes. 
Details of Morphology 
The formal description covers the salient morphologic 
features of this taxon, but, like all such descriptions, it is 
necessarily a constrained summary. Accordingly, we judge that 
a more elaborate discussion of certain aspects of the trail of 
Climactichnites wilsoni, combined with further illustration of 
specimens, will better convey our understanding of the trail 
maker. 
TEXTURE.?When compared to the surface of the bedding 
planes on which they occur, the oval impressions are smooth. 
As an example, the oval impression illustrated by Walcott 
(1912) is both smoother and slightly darker in color than its 
matrix, even though the sand is so fine that the rock appears at 
first glance to be an aphanic limestone. More significantly, 
because there are so many more examples, the entire 
trail?bars, furrows, and lateral ridges (Figures 21, 22)?is 
quite smooth when compared to the surrounding matrix. No 
matter how fine the grains of the sandstone, and no matter 
where the specimens were collected, invariably the trail is 
smoother than its surroundings, even in instances of exception?
ally poor preservation of the trail. 
From these observations, we were lead to the view that 
probably the animal secreted a great deal of mucus during its 
trail-forming activities. Such a secretion would have the effect 
of lubricating the substrate and assisting the motion of the 
organism as it moved forward. Unless a bar and furrow were 
made at the extreme posterior of an animal, it was difficult to 
envision what would prevent these structures from being 
modified or even obliterated by forward movement. However, 
a layer of mucus covering a set of bars and furrows already 
formed anteriorward would allow the posterior to slide over 
them and causing little or no distortion. 
One indirect result of mucus secretion is that this substance 
would bind the molded grains of sand, and protect the trail from 
the destructive effects of wind and incoming water. The mucus 
could entrap bacteria, other microorganisms, particles of 
organic matter, and clay-sized particles. These and the products 
of decay of organic matter would also serve to differentiate the 
22 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 17.?A ripple-marked topotype slab of C. youngi probably from the Galesville Sandstone at New Lisbon, 
Wisconsin (4), showing prominent lateral ridges on several Climactichnites trails. The trail near the middle of the 
slab, made by an animal moving right to left, and showing prominent lateral ridges crosses two below it The one 
moving toward the top of the illustration lacks the lateral ridges and is thus representative of C. youngi, as 
described. At the left of it, another animal moving in the opposite direction has a prominent lateral ridge only on 
the left before the point of crossing and both lateral ridges after this point. Thus, the absence of bounding lateral 
ridges may be a taphonomic feature. Scale is indicated by a 10 cm ruler. PNH 68/1. 
molded sand trail from the sand matrix. The smooth or even 
glossy surface of the trail can be interpreted as a result of early 
diagenesis relative to the matrix. The mucus might have served 
as a horizontal barrier inhibiting circulation of pore water and 
thereby concentrating some compounds below the film of 
mucus, and, perhaps, thereby speeding 1 Unification. 
On two slabs from the Battersea quarry (7) in the collections 
of Queen's University, the trails are outlined in a dark purple 
color (Figures 23, 24), in striking contrast to the light tan matrix 
of the slabs (Yochelson and Fedonkin, 1991). It is unlike both 
the red to brown of an iron oxide and the black of a manganese 
oxide; such stains have been seen on some of the outcrops we 
have examined. 
This color is confined to the sculptured sediment of the trail, 
specifically to the lateral ridges and to the upper part of the 
bars. On one lateral ridge as seen in Figure 23, the crenulations 
are delineated by the dark purple, supporting the interpretation 
that this color is not a secondary stain. We surmise that these 
trails were subjected to an atypical sedimentary regimen, 
possibly with longer than normal exposure to air, so that 
different chemical reactions affected these otherwise typical 
trails. The purple color is similar to that found in color-marked 
Paleozoic mollusks and brachiopods, and it may be a 
degradation product of a complex porphyrin. Whatever the 
particular cause of these color markings, they add support to 
our suggestion that large amounts of mucus were secreted by 
the animal during its movement. 
OVAL IMPRESSIONS.?Partly as a consequence of the small 
size of the sketch produced by Clarke (1905), the impressions 
at one end of the trails found at Mooers, New York (12), have 
come to be considered asymmetrical, more or less like a kidney 
bean in shape (Figure 25). With each reproduction of the 
NUMBER 74 23 
FIGURE 18.?The type slab of Climactichnites wilsoni Logan from Perth, Ontario (8), after removal from the wall 
of the National Science Museum in Ottawa. The surface is slightly undulatory, but is smooth except for a few low 
asymmetric ripples in the upper left, adjacent to the lectotype. Because this is a sole marking, all surface relief is 
reversed, so that the lateral ridges appear as dark depressions. The lectotype is from lower center to upper right 
The irregularity in both occurrence and position of the medial marking is evident among the five trails. A 
meshwork of Protopaleodictyon is prominent near the lower center, just to the left of the intersection of three 
trails. Protichnites is prominent at the lower right. Portions of this specimen are shown in Figures 11, 14, 19, 45, 
49, and 50. GSC photograph 201284B. GSC 6299. 
24 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 19.?A portion of the lectotype of C. wilsoni Logan, near the scale in Figure 11, showing the prominent 
crenulations of the lateral ridges, the asymmetrical and varying furrows and bars and a medial marking, all in 
negative relief on this sole marking. The orientation is rotated from Figure 18, the ripple marks on the left of that 
Figure are now seen above the impression. Scale is indicated by a 15 cm ruler. GSC 6299. 
sketch, this notion has continued. In fact, the impressions are 
more or less bilaterally symmetrical, the pronounced asymme?
try shown being an artistic artifact. Several of these features are 
more deeply impressed into the sediment on one side than on 
the other, and efforts to show this at a very small scale by 
shading resulted in the kidney-bean shaped rendering. 
Although there is some irregularity, these impressions are 
rounded at one end, with sides parallel. Oval is not accurate 
geometrically, but is a conveniently neutral morphologic shape 
term to use. However, we emphasize that it is only the posterior 
of the marking which is well rounded. The anterior of these 
impressions is distinctly not oval, and is interpreted as the 
impression of a triangular flap which may extend forward from 
one side of the animal or from the other (Figure 26). 
Most oval impressions are 1-3 cm deep. Invariably, they 
occur beneath the level of the trail, if only by less than a 
centimeter, as is the case with the New Lisbon, Wisconsin (4), 
specimen of Walcott (Figure 31). The impression may be 
deeper at either the anterior or posterior, and, as noted, deeper 
on one side than on the other (Figure 27). Seemingly, the 
animal moved upward from a depression to begin its trail 
forming activity. Depending on consistency of the sand and the 
precise movement, the bottom or one side of the impression 
may have been modified by slumping or movement of the loose 
sand. On at least one impression (Figure 26), there appear to be 
two axes of symmetry, best interpreted as an animal shifting its 
position; this also gives a superficial appearance of a curved 
shape. 
On the Mooers, New York, specimens, both as represented 
on the plaster cast and the actual specimens in the New York 
State Museum, most oval bodies are associated with trails. The 
provenance of the slabs of New York material in the Pratt 
Museum (Figure 28) has not been traced, but they appear 
remarkably similar to the Mooers material. One oval impres?
sion is particularly noteworthy in showing one end of the 
impression extending as a flap-like structure, the opposing half 
being represented by bars and furrows (Figure 29). It is even 
more convincing than any of the specimens in the New York 
State Museum that the right and left sides of the organism could 
move either alternately or coordinated. 
The New Lisbon, Wisconsin (4), oval impression (Figure 31) 
shows irregular ridge-like longitudinal bulges and furrows, 
confirming that the basal surface was not rigid. Similar 
irregularities, though not nearly so well preserved, occur on a 
few of the oval impressions from Mooers, New York. As may 
be seen on Figure 29, the flap-like anterior also shows 
NUMBER 74 25 
FIGURE 20.?Three oval impressions from Mooers, New York (12). The matrix of the Potsdam Sandstone is very 
fine-grained, yet it shows more of a texture than the impressions. The clearest impression is at the right, just to 
the left of the missing piece of rock. It is deeper in the sediment on the right side and the anterior shows the trail 
beginning to the left side earlier than to the left. The same feature may be seen in the part of the impression at the 
bottom. The impression to the left of the scale suggests that the animal shifted position and that a ridge outlining 
an anterior flap covered the left posterior of the first impression. Scale is indicated by a 15 cm ruler. GSC 6299. 
NYSM unnumbered 
irregularities. Overall, these suggest that the sole of the animal 
was covered by a tough integument, but one that had some 
flexibility, and that there was at least as much flexibility, if not 
more, at the anterior. 
Along the Chippewa River at Eau Claire, Wisconsin (2), we 
examined a large slab showing several trails, including an 
S-shaped one. One end of this S appears to be the impression 
of an oval body (Figure 30). It shows few details, but if our 
interpretation is correct, this is another locality for the oval 
impressions. 
Oval impressions thus are of two general forms. The single 
remarkably well preserved individual from New Lisbon (4) is 
a faithful replica of the sole of the animal. It shows both 
wrinkles of the integument and, as discussed below, fine detail 
on the integument. The impressions from New York are much 
less well-preserved and represent impressions modified par?
tially by slumping as the animal moved upward from its shelter 
within the sand. 
ARCHED LINES.?The excellent oval impression from New 
Lisbon, Wisconsin (4), illustrated by Walcott (1912) and by 
Burling (1917), is preserved as both part and counterpart 
(Figure 31). On both surfaces, it shows a series of fine, closely 
spaced arch-like wrinkles, having the same curvature as the 
posterior end of the impression. As illustrated by Walcott and 
Burling and reillustrated herein, the arched lines can also be 
seen crossing bars and furrows; they are more prominent on the 
gentle (distal) slope of the bars (Figure 32) than elsewhere on 
the trail. 
Two slabs in the Museum of Comparative Zoology, Harvard 
University, also show these delicate arched lines. These slabs 
26 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 21.?Five trails of Climactichnites on part of a slab of Potsdam Sandstone from Port Henry, New York 
(14), on a bedding plane bearing numerous interference ripple marks; this is a sole marking, so surface relief is 
reversed. The trails are smoother than the matrix. Near the center of the slab the trails proceed in opposite 
directions. Scale is indicated by a 15 cm ruler. MPM 27629b. 
NUMBER 74 27 
appear to be similar to the New Lisbon specimens, but their 
provenance is unknown. None of the other specimens we have 
examined is well enough preserved to show these features. 
PROXIMAL STRUCTURE.?On about half a dozen of the oval 
impressions from Mooers, New York (12), we observed a 
circular structure, slightly raised, near the anterior end of the 
impression (Figure 33). The newly discovered oval impression 
along the Chippewa River (2), alluded to above, shows a slight 
elevation in the same area. However, the slab at the Pratt 
Museum (Figure 28) shows them both in the oval impressions 
and elsewhere on the slab. Presumably, these are "sand 
volcanoes" formed by incoming water forcing air and sediment 
upward; slightly greater consolidation of the sand below the 
animal may account these features being relatively more 
common within the impressions. No such large mounds are 
known to cut any of the trails we have examined. 
There is, however, another feature in the oval impressions, 
which is not easily explained as a sedimentary structure. On the 
Beauharnois, Quebec (10), slab at the National Museum of 
Natural History, three concentric rings are present on an 
incomplete oval impression (Figure 34). Two other examples 
are known of circular features which are centrally located on 
the trails. On a slab from Port Henry, New York (14), in the 
American Museum of Natural History, medial circular areas 
occur on a trail; these have a more roughened texture than 
surrounding bars and furrows (Figure 35). On another slab from 
the same locality in the Milwaukee Public Museum, one clear 
oval impression may be seen (Figure 36). On another trail on 
this same large slab, two, centrally located, small cones are 
present. 
OVERALL FEATURES OF THE TRAIL.?One of the novel 
features of Climactichnites is the constant width of any 
individual trail (Figure 37). Regardless of whether the trail is 
straight, curved, or slightly sigmoidal, the lateral ridges remain 
separated by the same distance. The examples of trails crossing 
over themselves, sketched by Clark and Usher (1948) (Figure 
38) show a remarkably small radius of curvature. We have 
confirmed this by finding a specimen at St. Hermas (8) which 
crossed its own trail (Figure 39). The small radius of turning is 
impressive and suggests that the animal did not stretch out 
significantly when moving. The oval impressions made while 
FIGURE 22.?Latex replica of portions of three trails and of ripple marks on a slab from Port Henry, New York 
(14), showing the smooth bars and furrows and the coarser texture of the ripples. The longest trail was made by 
an animal moving toward the lower right Scale is indicated by a 15 cm ruler. USNM unnumbered. 
28 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 23.?Slab from Battersea, Ontario (7), showing two trails outlined by a distinct darker color, with similar 
color on the top of a few of the bars. The matrix of the slab is a brownish yellow and the color on the specimen 
is a dark purple. Scale is indicated by a 15 cm ruler. Miller Museum 2380. 
the animal was at rest may also accurately reflect the 
approximate size of the moving animal. 
On the many slabs that we have examined, we have seen no 
evidence of a preferred direction of movement. The large 
assemblage sketched by Clarke (1905) (Figure 40) suggests 
some directionality, but even here some animals moved in an 
opposite direction, and a few are at an oblique angle to the 
majority. The slabs collected by Dr. B.R. Erickson likewise 
show randomness in the direction of movement (Figure 40). 
On some slabs, trails indicating one direction of movement 
are parallel to those showing the opposite direction of 
movement (Figure 41). We have considered the possibility that 
Climactichnites was proceeding in a meandering pattern, the 
most characteristic pattern among grazing trails. The common 
Precambrian to Recent trace fossil Helminthoida has a trail 
about 1.5 mm wide and has a meander range varying from 
about 10-50 cm. If the same proportionality of meandering 
were applied to Climactichnites, meanders in the range of about 
4-40 m might be expected. Most slabs are not sufficiently large 
to confirm or refute the maximum figure. However, the surface 
exposed at Au Sable Chasm (13), the scattered trails along the 
Chippewa River (2), the type slab from Perth (7), and the sketch 
of Clarke of the Mooers outcrops (12) show sufficient area to 
suggest that a rigid meandering behavior is extremely unlikely. 
The trails have a superficial appearance of loose material 
which has been pushed forward. On a ripple-marked surface, 
the trail passes through a ripple crest as though it pushed 
forward like a snowplow or a bulldozer; similarly when one 
trails crosses another there is minimal lateral disturbance to the 
underlying trail. However, Climactichnites differs fundamen?
tally from either of these mechanical comparisons in that the 
central area is not smooth, but bears the bars and furrows, 
which give the ladder-like appearance. Comparison of the trail 
to a rope ladder lying on the ground is an even better analogy. 
LATERAL RIDGES.?The trails are bounded by prominent 
parallel lateral ridges, raised above the bedding plane, though 
these are not always preserved. Characteristically, the lateral 
ridges are higher than the bars which lie between them. There 
is a general size relationship in that the wider the trail, the larger 
and the higher the ridges. On smaller specimens, ridges are 
NUMBER 74 29 
FIGURE 24.?Slab from Battersea, Ontario (7), showing three trails outlined by a distinct color. Because this is a 
sole marking, the surface relief is reversed and the dark color on the bars occurs in depressions, accentuated by 
the low oblique light; a color illustration of this slab has been published (Yochelson and Fedonkin, 1991). Scale 
is indicated by a 15 cm ruler. Miller Museum 2381. 
nearly hemispherical in cross section, where not compressed, 
but on very large specimens they are slightly higher than wide, 
where not compressed. 
The inner face of the lateral ridge is more uniform than the 
outer face, but in some examples the ridge may be narrower 
adjacent to a bar. The outer face of the ridge may be even, but 
far more commonly, on well-preserved specimens, it is 
crenulated (Figures 42, 43). There appears to be no correlation 
between height and width of ridges and presence or absence of 
such crenulation. There is also individual variation along the 
length of some trails in the presence of nearly uniformly spaced 
crenulations; crenulations may disappear and then reappear in 
less than a meter. 
The crenulations tend to be spaced almost equally along a 
lateral ridge, though there is some variation in the distance 
between these indentations. On at least some specimens, the 
deepest part of the crenulation coincides with the top of a bar. 
Not unexpectedly, the crenulations are most prominent on the 
largest specimens, but on well preserved specimens where the 
lateral ridges are as narrow as 5 cm, we have observed faint 
indentations on the outer faces of the ridges. It is possible that 
the presence or absence of crenulations is related to the amount 
of pore water in the damp sand. This relationship would, in 
effect, control the amount of source material available for the 
ridges, as would the ability of the individual animal to move 
and compress loose sediment. 
30 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 25.?Part of plaster cast of slab from Mooers, New York (12). The impression is not kidney-bean shaped, 
though several interpretations are possible. The preferred one is that an animal settled at nearly a right angle to the 
trail in the lower right and began to move toward it. A rim of sand indicates the animal stopped just after 
intersecting the earlier trail. Later, another animal settled at a slight angle to the first, partially obliterating the 
lower impression. This one faced toward the top of the photograph and its impression is deeper toward the left. 
Slight movement formed a ridge to the left side and a sand slide occurred to the right. The irregular ridge in the 
upper left reflects an anterior flap. Scale is indicated by a 15 cm ruler. NYSM public display. 
NUMBER 74 31 
On some specimens both lateral ridges and bars are absent. 
Rarely traces of bars may be seen without the lateral ridges, but 
there are no examples of lateral ridges retained and medial bars 
absent. Of the specimens which lack lateral ridges, the one 
which Walcott illustrated as C. youngi is an excellent example 
(Figure 44). 
BARS AND FURROWS.?Between the lateral ridges, elongate 
depressions and elongate ridges are present. The term "bar" is 
used for these inner ridges to avoid confusion with the 
continuous bounding ridges. 
The furrows are narrow depressions nearly parallel-sided 
throughout most of their length, tapering to a point toward the 
center of the trail and rounded near the ridge. Commonly these 
depression are straight, but they may be gently arcuate. They 
may be as deep as 1 cm in exceptionally large specimens. The 
furrows are inclined at an acute angle to the adjacent lateral 
ridge; few examples of furrows at right angles to a ridge are 
known. Typically, one end of the furrow nearly touches a 
lateral ridge and a distinct, central non-furrowed area of the 
bedding plane separates the two rows of furrows. 
The bars are raised and, like the furrows, are inclined to the 
lateral ridges. They are longer than the furrows and extend 
medially to the axis of bilateral symmetry. If bars from either 
side touch, there is a medial irregularity. 
One important feature of the individual bars is their 
consistent asymmetry, as seen in profile along the length of the 
trail, being steeper on the forward (distal) side. The bars are 
more strikingly asymmetrical than the furrows and, in general, 
the larger the bar, the greater the asymmetry. Although it is 
almost impossible to make any observations in the third 
dimension, one exceptionally large paralectotype is broken 
along several laminations in the sandstone, revealing inclined 
structure at three levels (Figure 45). Such internal structure 
would not be seen if the trail were the result of the animal 
plowing forward. This suggests to us that the bars are at least in 
part built up and have a structure like miniature sand dunes. 
FIGURE 26.?Another part of the same plaster cast showing, below the scale, an oval impression leading into a 
trail. Within the impression the sediment surface has been modified and the right side of the impression is lower 
than that to the left. The trail begins sooner on the left side than on the right and supports the notion of an anterior 
flap on the right side. Another trail, above, also begins at a depression at the right side of the photograph. This has 
an angular anterior and bars appear on the right and left for about five centimeters before they become continuous 
between the bounding lateral ridges. The lateral ridges are crenulated after the animal left the oval impression. 
Both impressions are deeper than the trails. Scale is indicated by a 15 cm ruler. NYSM public display. 
32 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 27.?Another portion of this same plaster cast showing two impressions. The one at the top adjacent to 
the trail is hardly impressed into the surface. The trail extending from it is obscure, but there is a suggestion that 
it begins on the left and that a flap extended forward on the right. The impression below is more deeply impressed, 
but less so on the right side at the lower part of the photograph. Scale is indicated by a 15 cm ruler. NYSM public 
display. 
In addition to the internal structure of the dune-like bars seen 
on the type slab, several smaller specimens from the Northern 
Stone Company quarry (5) display inclination of layers on the 
sawn surface of bars, though not clearly enough to reproduce 
photographically; we have no material of a large trail which 
may be sectioned. These observations demonstrate that the trail 
is a surface phenomenon. In spite of the difficulty of 
compacting sand, an animal traveling over the surface by some 
sort of undulatory motion might?at least in theory?press the 
sand down into furrows. Even though pressure on the surface 
might result in forming a ridge, it would never result in a ridge 
having internal dune-like structure near the top. 
Even though Climactichnites is conventionally depicted as 
showing uniform V-shaped bars (Figures 21, 22), in fact this 
form is quite rare. Individual arms of the V may be offset 
(Figure 46). Local asymmetry may also occur with a bar 
emplaced at irregular intervals along one side of a trail (Figure 
47). Rarely the bars and furrows may be straight across at right 
angles to the bounding lateral ridges (Figure 42), more 
commonly they are at an acute angle to the bounding ridges, 
and in some examples they are highly irregular (Figure 48). On 
other trails the bars may be gently arched or may show greater 
curvature locally (Figure 49). Some bar and furrow systems are 
sigmoidal (Figure 50). 
The amount of individual variation evident in the trails is 
remarkable. In addition to its unique morphology, in this 
feature of great variability, the trail of Climactichnites is unlike 
any other fossil trail we have examined. It is theoretically 
possible that the variation in trails represents more than one 
activity, for example conventionally feeding with locomotion, 
and rarely only locomotion. We know of no way to test such a 
hypothesis, but it is possible that sigmoidal trails which 
emphasize movement by one side of the animal (Figure 43) 
represent rapid locomotion. 
Despite our best efforts, we have been unable to develop any 
correlation between width of trail and inclination of the bars 
and furrows to the lateral ridges. On one slab in particular 
(Figure 51), we have noted that areas of incomplete bar 
NUMBER 74 33 
FIGURE 28.?Two slabs of the Potsdam Sandstone from "N.E. New York," possibly from Mooers, New York 
(12). An oval impression is present at the upper right and a second, broken off, occurs at the top of the slab. Sand 
mounds or "volcanoes" are present on the slab, which probably formed when incoming water forced air upward. 
Portions of this specimens are shown in Figures 29, 53, and 54. Scale is indicated by a 10 cm ruler. PNH 98/1. 
formation and asymmetry of several trails coincide. This 
observation suggests to us that the degree of moisture in the 
sand may have had a profound effect on details of the trail. It is 
as though these animals crossed an area of wet sand. 
Another feature is the loss of lateral ridges and bars even 
though detail in the furrows is retained (Figure 52). The key to 
interpreting this peculiarity was found on the two matching 
large slabs in the Pratt Museum (Figure 28). Unfortunately the 
number on these slabs is not listed in the museum catalogue and 
the accompanying label gives only the general information of 
northeastern New York. However, the slabs bear oval impres?
sions along with the trails and, in color and texture, they are 
similar to the material from Mooers, New York. Because John 
M. Clarke was a student of Prof. B.K. Emerson of Amherst, it 
is reasonable to assume that he permitted Amherst College to 
remove material from his temporary quarry. 
Some trails preserved on these slabs have no trace of lateral 
ridges or bars (Figure 53); the furrows which do remain serve 
to delineate the trail. The most logical interpretation is that 
these incomplete trails were formed later than adjacent 
complete ones, and there was not sufficient time for them to 
harden before incoming water washed away the ridges and bars 
which rose above the surface. This interpretation of the loss of 
ridges and bars emphasizes the importance of a secretion in 
hardening the trails. 
Two of the trails which lack lateral ridges and bars on the 
large slabs in the Pratt Museum show other curious features 
(Figure 28). The furrows become shorter so that the medial area 
is undisturbed. They also become shorter and cease abruptly 
(Figure 54). 
MEDIAL RIDGE.?On some specimens (Figures 18,55) a low 
ridge may overlie some of the bars and furrows. This feature 
varies in presence or absence among the trails observed and on 
long trails may be seen to start and to stop along the length of 
the trail; neither the beginning or end of the ridge is prominent. 
This feature varies in position between the lateral ridges along 
a trail and also varies in its prominence (Figure 56). 
Abundance and Size Distribution of Trails 
Where it occurs, Climactichnites is both widespread and 
abundant. For example, in the lower level of the Northern Stone 
34 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 29.?Upper right quadrant of the slab shown in Figure 28. The oblique anterior of the impression at the 
upper right is clear; the rounded posterior is broken away. Irregularities just behind the oblique ridge suggest that 
this anterior portion was relatively flexible. The scale partially obscures another oval impression. At the far left 
and lower center, sand mounds occur. Scale is indicated by a 10 cm ruler. PNH 98/1. 
Company quarry, Wisconsin (5), we counted in excess of 50 
trails in an area of approximately 400 square feet; one 
modest-sized slab from this quarry shows six trails (Figure 46). 
Along the Chippewa River in Eau Claire (2), we saw 
approximately 50-60 trails in scattered outcrops along less 
than a kilometer of river bank; no doubt many more would have 
been found if the water level were lower and the outcrop 
continuous. More than two dozen occur on a slab collected by 
Dr. B.R. Erickson along the Black River (3) (Figure 40, 
bottom). 
Nearly a dozen trails occur on the type slab from Perth, 
Ontario (8) (Figure 18), and more than that are seen on the 
display material from Beauharnois (10) in the National 
Museum of Natural History (Frontispiece). Although the 
collection at Queen's University contains only two slabs, there 
is anecdotal information of a large number of trails on slabs 
from the Battersea quarry (7) which were subsequently paved 
over; one of the remaining slabs bears three trails (Figure 24). 
At Melocheville, Quebec (10), Clark and Usher (1948) reported 
many trails on the quarry floor. Clarke (1905) sketched nearly 
two dozen in about 300 square feet of outcrop at Mooers, New 
York (12) (Figure 40, top). Near Alexandria Bay, (11), a 15 x 
30 cm slab shows eight trails. At Au Sable Chasm (13) we 
estimate at least 25 trails in an area of about 100 square feet. A 
piece about five feet square in the New York State Museum 
from Port Henry (14) contains more than a dozen large trails. In 
light of both the broad geographic distribution and local 
abundance of these trails, the notion that Climactichnites is a 
"chance occurrence" of a rare pelagic animal swept inland by 
abnormal conditions, such as a great storm or tsunami, is 
untenable. 
Despite limited information available from the outcrops, we 
are left with the impression that Climactichnites was more 
abundant on the sand flats on which oscillation ripples had 
formed than it was on the smoother surfaces. Another 
observation, supported by more data, but still qualitative, is the 
FIGURE 30.?Surface of a loose block of Mount Simon Sandstone on west side of Chippewa River, just below the 
dam at Eau Claire, Wisconsin (2). The ridges below the scale outline the posterior of an oval impression. The 
animal then presumably crawled toward the left forming a sigmoidal trail. Scale is indicated by a 15 cm ruler. 
limited size range of trails at any one locality. Small trails in the 
range of 6-8 cm in width are known only from the lower level 
of the Northern Stone Company quarry (5). Medium-sized 
trails (8-12 cm) are widespread, as are large ones (13-18 cm), 
but these two general groups almost never occur on the same 
slab. Our interpretation is that this was directly related to the 
characters of the substrate, smaller animals requiring a different 
moisture content than the larger ones; presumably smaller 
animals would find it more difficult to move sand heavily 
saturated with water. There are a few instances in which a 
narrower width trail will occur with larger ones, but such 
distributions are exceptional. 
Earlier Views on the Origin of Climactichnites 
In summarizing the various views which have been proposed 
as to the nature of Climactichnites, it may be helpful to consider 
the works more or less in chronological order rather than by the 
group of organisms to which they suggested the trail maker 
belonged. 
In his original description, Logan (1860:285) did not discuss 
locomotion. He ended his paper by noting "My naturalist 
friends to whom I have exhibited the specimens, appear 
disposed to consider the tracks those of some species of 
gigantic mollusk " Notwithstanding this first published 
opinion, the notion of molluscan affinities did not prevail and 
vanished for nearly half a century, to be replaced by emphasis 
on various arthropods. 
Jones (1862a) suggested that this fossil was a collapsed 
burrow, or gallery track, of a crustacean moving below the sand 
surface. The same year (Dawson, 1862) noted the error of this 
supposition, pointing out that the fossil was a surface trail. That 
comment was ancillary to experiments Dawson conducted with 
a living Limulus crawling on a beach. Because the Potsdam 
Sandstone was an ancient rock and living Limulus a "primitive" 
animal, there was considerable logic behind this early 
experiment in the "actuopalaeontologie" of a trace fossil. 
Dawson observed that under different conditions of subaerial 
and littoral depth, and thus sand moisture, Limulus produced 
markings similar to either Protichnites or Climactichnites. 
"The supposition in regard to Climactichnites has been that 
it is possibly the track of a gasteropod [sic] or an annelid; but 
my recent observations of Limulus show that it may have been 
produced by a crustacean moving by a broad swimming foot, 
having a median notch like that in the largest pair in Limulus'" 
(Dawson, 1862:274). Dawson went on to note that for this 
animal to produce the trail in question it would need more 
mobile and stronger swimming feet and the telson should not 
drag on the sediment. Further, he did mention that his living 
specimens produced lateral and medial furrows in the sand 
rather than ridges, an important difference. Jones (1862b:455) 
immediately recognized the significance of this difference and 
repeated his concept: 
The great well-known North American trilobites {Paradoxides), however, 
whose bodies exactly fit in width to Climactichnital and Protichnidal trails of 
Canada, and whose abiding place was really the muddy-sea bottom on the 
36 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
geological horizon of the Potsdam sandstone, in all probability crawled over 
these littoral sands, just as the Limulus ... and ... it may have burrowed in them 
with much longer burrows than Limulus makes, and in that case the in-fallen 
galleries would supply the raised ridges of the Climactichnite. 
Billings (1870:484-485), partly on the absence of any 
limulid body fossils having been found in the Potsdam 
Sandstone, suggested that both Climactichnites and Protich?
nites were formed by a large trilobite. During this time, the 
issue of trilobite limbs was still a point of uncertainty, and it 
was not until later in the decade that the presence of limbs and 
some of the details of their morphology was documented by 
Walcott. It is also helpful to recall that throughout most of the 
19th century, trilobites and limulids were considered by many 
paleontologists to be crustaceans. Markings possibly made by 
trilobites on the bottom were a concern in trying to determine 
something of the life habits of these animals. 
In his classic textbook, Zittel (1881-1885:591) did not 
provide any illustration of Climactichnites. He allotted the 
genus only a phrase in mentioning several forms from the 
Potsdam that might be evidence of early limulids or eu-
rypterids. Nicholson and Lydeckker (1889:525) followed 
Dawson's views in their textbook. 
In his compendium of North American fossils, Miller 
(1889:538-539) placed Climactichnites under Crustacea, but 
was cautious enough to note: "It may not be the track of a 
Crustacean." Lesley (1890) reproduced the drawings which 
Hall in turn had reproduced from Logan's original work. Lesley 
(1890:1192) added nothing new, but he nicely paraphrased 
Hall's view: 
.. .that the animal seems to have had no free moveable limbs, or otherwise very 
short ones, without the sharp appendages belonging to Limulus; and that the 
only reason for calling the tracks crustaceans is our ignorance of the existence 
at that time of any larger creatures than Trilobites and one Limuloid. 
Nearly three decades after his original investigation, Dawson 
returned to the theme of Limulus as a present-day model for 
Climactichnites. In his will, Sir William Logan left funds to pay 
for the replacing of fossils which had been removed from 
Montreal when the Geological Survey of Canada was trans?
ferred to Ottawa. As a consequence, the Redpath Museum hired 
Richardson to collect, and obtained a single large piece of 
sandstone from Perth. This new material may have inspired 
Dawson, who emphasized trilobite burrowing structures, now 
generally placed in Rusophycus and Cruziana, as germane to 
FIGURE 31.?Counterpart (sole marking) of specimen probably from the Galesville Sandstone at New Lisbon, 
Wisconsin (4), illustrated by Walcott (1912) as C. youngi, showing the impression of the base of an oval 
impression; compare with Figure 44. The fine arched lines cross the irregular elongate ridges and furrows. The 
slightly coarser arched lines near the top right may mark the first stages of trail formation. The matrix is 
exceedingly fine, but as in other examples, the impression is smoother than the matrix. Scale is indicated by a 15 
cm ruler. USNM 58544. 
NUMBER 74 37 
FIGURE 32.?Detail of a portion of a slab probably from the Galesville Sandstone at New Lisbon, Wisconsin (4), 
shown in Figure 51. This was illustrated by Walcott (1912, pi. 39: fig. 2) as C. youngi, and reillustrated by Burling 
(1917). Although Burling corrected the direction of movement, neither he nor Walcott noted that the lateral 
bounding ridges are not present. The arched lines are preserved on the gentle (distal) slope of the bars, and not on 
the steep (proximal) slope. Even though no lateral ridges are present, the sharp prong-like edge adjacent to them 
is evident on the right side and is comparable to the same feature in Figure 43. Scale in centimeters. USNM 58545. 
38 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 33.?Two oval impressions, separated by a ridge, and a portion of a trail from Mooers, New York (12). 
A "sand volcano" or sand mound is on the compacted surface of the impressions. Scale is indicated by a 15 cm 
ruler. NYSM unnumbered. 
the issue of the Potsdam Sandstone trail maker (Dawson, 
1890:601). 
From all the phenomena attending the Potsdam Climactichnites, I am now 
inclined to regard them as of this nature, and as implying the existence of a large 
Crustacean with a truncated tail divided into two moveable lobes. This would 
account for the ridge sometimes dividing the furrows and transverse ridges, and 
for its change in position from side to side of the mesial line, -also for the 
interrupted ridge on each side of the trail, which would be the natural result of 
the successive strokes of a flat organ, -and for the appearance presented when 
the tracks turn abrupdy. 
The large topotype slab (Figure 55) was illustrated by him, and 
with that length of trail material available to him, he therefore 
should have had a better notion of the large degree of individual 
variation both among trails and along a single trail. In this 
paper, Dawson's earlier published "may" became a certainty, 
and his comment that crawling Limulus produced furrows in 
the substrate simply disappeared. 
Like Nicholson and Lydeckker, Dana mentioned Climacti?
chnites in several editions of his textbook, and in the final 
edition, he (Dana, 1895:479) reproduced reduced sketches of 
all three named species. In a previous sentence, he had 
mentioned large specimens of the trilobite Dicellocephalus. 
"The track.. .from Perth.. .has been referred to a large Trilobite, 
on the view that the limbs of the species were natatory... .The 
partial natatory character of the limbs has recently been 
established...." By this, Dana was referring to the then new 
discoveries of the limbs of Triarthrus becki Green at Rome, 
New York. Dana presumably assumed that the movement of 
the swimming limbs of a trilobite could form a trail when it 
scurried along the bottom. 
Packard, a specialist on living arthropods, reinforced the 
interpretation of this fossil as that of an arthropod by simple 
repetition (Packard, 1900:65). 
Logan's Climactichnites wilsoni, six and a half inches wide and thirteen feet 
long, also from the Potsdam sandstone, which Dana suggested may have been 
made by a large trilobite, seems to be such. There is an interrupted median 
furrow; the oblique furrows probably were made by the legs, and the lateral 
furrow bounding the track is much like that made by the cheeks or sides of the 
head of Limulus. 
Again furrows and ridges were confused probably because this 
zoologist was not familiar with the concept of impressions on 
the bottom of overlying beds, as Logan had illustrated, and was 
further misled by Dawson's comments. 
Gratacap (1901:89) suggested that: "Climactichnites and 
Protichnites may all be the repant impressions of broad ringed 
worms." He gave no further information at the time to support 
this novel interpretation and seemingly never elaborated on it. 
Woodworm (1903) provided an important addition to the 
NUMBER 74 39 
FIGURE 34.?Three concentric markings on an incomplete oval impression, cut off above and below by trails, 
from Beauharnois, Quebec (10). The area below the scale in this view having a different texture is restored in 
plaster to simulate ripple marks. The area illustrated is near the center of the Frontispiece. Scale is indicated by 
a 15 cm ruler. USNM public display. 
morphology of Climactichnites with his discovery of an oval 
impression at one end of some of the trails (see Figure 40, top). 
In another piece of experimental ichnology he pushed a small 
board through sand to simulate the trail. He concluded that 
arthropod limbs, including the specialized organs of limulids 
and eurypterids, were incapable of producing the trail of this 
fossil. 
Following the suggestion of a Professor Walter Faxon, 
Woodworm then proposed polyplacophoran mollusks as the 
putative trail formers, probably influenced in part by the shape 
of the oval impressions (Woodworm, 1903:965). 
The mantle of the Chiton extends beyond the shells; they have a powerful foot 
for attachment to rock surfaces; though habitually attached to rock surfaces, 
they can crawl very slowly over sand; they can roll themselves up into a ball as 
did many trilobites; the retractile forward hitching movements of the foot of a 
large Chiton, moving inch by inch, might have given rise to smoothened, 
cross-ridged trails known as Climactichnites; and the sedentary animal with 
retracted foot, the terminal impressions seen at Mooers. No other existing form 
seems so readily capable of producing the assemblage of phenomena. But it is 
equally possible that some large sea slugs of the order Aplacophora may have 
produced the trails and the terminal impressions, though the modem 
representatives of these primitive gastropods are not littoral animals. Further 
than the suggestion of a molluscan origin for these terminal impressions and the 
connected trails, it does not seem possible at present to seek definite 
conclusions. 
This return to a molluscan comparison was ignored, for 
Limulus and its allies were considered as putative trail makers 
by Hitchcock and Patten (1908:382) in an abstract; no 
subsequent publication was produced. Hitchcock was one of 
the sons of Edward Hitchcock and may have seen the plaster 
casts of Logan's type lot in the Pratt Museum; Patten devoted 
his life to the study of Limulus. The abdominal gill plates of 
eurypterids were considered by them as an appropriate 
morphology for forming the bars in the Climactichnites trail. 
The writers referred to a slab installed in the Butterworth 
40 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 35.?Four circular slightly roughened areas in the central part of a trail from the Potsdam Sandstone from 
Port Henry, New York (14). This is a sole marking, so the surface relief is reversed; the prominent crenulations 
of the lateral ridge seen to the right side of the trail are accentuated by shadows in the depression. Scale is in 
centimeters. AMNH unnumbered. 
NUMBER 74 41 
Museum and indicated that the trail began at a depression and 
rose through the sand, as in the manner of a modem Limulus. 
After considerable investigation, we have found that the 
Butterworth Museum was at Dartmouth College in New 
Hampshire. Chamberlin (1883:133, footnote) noted that the 
Reverend A.A. Young obtained about half a ton of slabs 
bearing Climactichnites for Beloit College, and "He also 
supplied the University of Wisconsin and Dartmouth College 
with specimens." It is likely that the depression mentioned by 
Hitchcock and Patten was an oval impression, as illustrated by 
Walcott (1912) from New Lisbon, Wisconsin (4) (Figure 44). 
Unfortunately, the Butterworth Museum has been dismantled 
and the slab or slabs mentioned in the abstract no longer exist 
(Dr. G.D. Johnson, oral communication, 1991). According to 
Dr. Johnson, inquiry to a retired faculty member who was an 
undergraduate at Dartmouth brought a recollection of many 
slabs of dinosaur tracks on the walls, but nothing of 
Climactichnites. 
In an extended footnote, Clarke and Ruedemann (1912:85-
86) repeated with favor much of the short abstract of Hitchcock 
and Patten. They suggested that the Cambrian eurypterid 
Strahops would have been capable of making the trail, and they 
were the first authors to specifically consider eurypterids as 
putative trail formers for Climactichnites. Against this view, 
they cited the direction of movement suggested by Woodworm 
(1903), toward the oval, as being unlike the habits of Limulus 
and therefore opposed to this interpretation. With the reinter-
pretation by Burling (1917) as to the direction of movement, 
that concern vanished. Nevertheless, this footnote was essen?
tially the last significant mention of arthropods?be they 
crustaceans, eurypterids, limulids, or trilobites?in connection 
with Climactichnites. 
In their textbook, Grabau and Shimer (1910:89) described C. 
wilsoni but did not illustrate it. They remarked: "The trail has 
been generally recognized as that of some crustacean. It may 
have been made by some unknown terrestrial or semiterrestrial 
animal." They referred to the work of Woodworm (1903) but, 
notwithstanding that, the genus was placed in their chapter on 
Phylum Annulosa, under Class Annelida, Order Polychatea, 
Suborder Errantia, and in the final section titled "doubtful 
FIGURE 36.?Portion of a slab of Potsdam Sandstone from Port Henry, New York (14). In spite of the reversal of 
surface relief on this sole marking, the circular area in the curved trail above and to the right of the scale is similar 
to that shown in Figure 34. Scale is indicated by a 15 cm ruler. MPM 28389. 
42 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
affinities." Discussion of a possible crustacean among the 
worms is a bit strange, but on the other hand, their mention of 
a terrestrial animal was perceptive. 
In a footnote to his study of Cambrian merostomes, Raasch 
(1939:7, footnote) effectively ruled those animals out as related 
to Climactichnites; he did not suggest any group as related to 
the trail maker. 
There is of course a vast disparity of age between the Wisconsin 
Climactichnites and Aglaspis barrandi, the former being below the earliest 
Upper Cambrian fauna, the latter in the latest. There are, however, abundant 
merostome fragments in places in the earliest fauna, the Cedaria fauna of the 
Eau Claire division, but this lies still more than 100 feet above the horizon of 
the trails. Conversely, where merostomes are abundant, no trails of 
Climactichnites or Protichnites types have been observed. 
The same year that eurypterids were suggested as the 
putative trail former, Walcott (1912) described Climactichnites 
specimens from New Lisbon, Wisconsin (4). He refuted the 
chiton hypothesis put forth by Woodworm (1903) and 
suggested that the trail of Climactichnites might have been 
made by the movement of some large annelid worm (Walcott, 
1912:201). 
Among the Burgess shale forms there is a large Chaetopod worm (Pollingeria 
grandis), a crushed specimen of which has a length of 13 cm, width 7 cm. The 
larger scales found in the same layer of shale indicate that some individuals 
attained near twice that size. Such an annelid would have had sufficient size, 
weight and strength to make the Climactichnites trails. Among recent annelid 
species of the Aphroditidae attain a large size and some have a shallow water 
habitat and crawl about on the wet sand between tides. 
Seemingly the concept of worm origin for this trail was 
independently arrived at by Walcott, for he did not give a 
reference to the comments by Grabau and Shimer (1910). In the 
textbook by Zittel (1913:142), Climactichnites trails are not 
illustrated and are mentioned as "of uncertain origin but may be 
those of some large crustacean." A long footnote gives a 
comprehensive review of the literature, including the 1912 
paper by Walcott. More or less like the classification given in 
the Grabau and Shimer textbook, although Zittel suggested 
Climactichnites was a crustacean, it was inexplicably placed in 
Phylum Vermes, Class Gephyrea. 
After his analysis of the details of the trail and the direction 
of movement from the oval impression, Burling (1917:397) did 
not suggest any assignment to phylum. He concluded that data 
FIGURE 37.?Trails on a slab of Potsdam Sandstone from Port Henry, New York (14), showing no directionality. 
The troughs of interference ripples are standing in strong relief on this sole marking; the irregularities in the ripple 
marks may represent another later current direction. Scale is indicated by a 15 cm ruler. NYSM unnumbered. 
NUMBER 74 43 
were sufficient to emphasize "that Climactichnites was made 
by the snail-like creep of a flexible slug-like animal which was 
frequently stranded at low tide, but was able to swim in waters 
of the full tide, have passed the stage of guess-work and border 
on the real." 
Based on observations he made of living gastropods 
crawling, Raymond (1922:111) returned to the original idea 
published by Logan: "Climactichnites is essentially the same 
sort of trail made by Littorina... ."Raymond referred to the work 
of Woodworm (1903) and Walcott (1912) but apparently was 
unaware of that by Burling (1917). He pointed out that the trail 
of a Littorina may bear transverse ridges which are directed 
forward as in the Walcott material, quite unaware that this 
orientation was reversed. 
In 1925, Abel (1935:242) visited Albany, New York, and 
examined the trails collected from Mooers, New York; he was 
the first to publish a photograph of one of those oval markings. 
As a most unexpected piece of humor in his work, he noted a 
story attributed to R. Ruedemann that the local farmers 
considered the oval impression at the start of the trail to be a 
mark of the footprint of Christ stepping on a serpent, an 
imaginative folk legend. He then considered in some detail the 
various notions which had been put forth as to the animal which 
may have formed the Climactichnites trails. Not only did he 
then decide that Climactichnites was of molluscan origin, like 
Raymond (1922), he was firm in his opinion that the trail 
formed by movement of a gastropod. Indeed, he suggested a 
shell-less opisthobranch, though he was aware of some of the 
problems in this interpretation. 
Shimer and Shrock (1944:799) reproduced Clarke's sketch 
of 1905, but mixed the figure caption with that of Protichnites, 
adding a minor bit of confusion. They covered the various 
possibilities as to origin in writing: "This trail may be that of an 
extinct crustacean, mollusk, or annelid worm, or possibly some 
other extinct Cambrian organism." In confirming the direction 
of movement interpreted by Burling, Clark and Usher (1948) 
did not contribute any opinion as the kind of animal which 
made the trail. 
A description of Climactichnites was given by Hantzchel 
(1962:W-188) in the "Treatise on Invertebrate Paleontology" 
wherein he suggested that the trail was: "Probably formed by 
mollusks, arthropods, or worms." This was in the Treatise 
tradition of mentioning all opinions, but remaining neutral. 
Subsequently, an excellent brief general account of the salient 
literature was prepared by Malz (1968) in which he attributed 
FIGURE 38.?Sketches reproduced from Clark and Usher (1948:252, 253) of 
trails crossing over themselves on the quarry floor at Melocheville, Quebec 
(10). Top: The caption for the smaller (upper) figure is "Figure 2. 
Climactichnites wilsoni Logan, a normal size trail showing the relationship 
between the V-shaped markings and the direction of progression." Bottom: The 
caption for the lower is "Figure 1. Climactichnites wilsoni Logan. A narrow 
trail showing by two intersections the direction of progression, and also the oval 
body at the beginning of the trail." 
L J 
0 2 ^ 
Scale 
6 6 10 12 
In inches 
L 
0 2 ^ 6 
Scale in 
J 
a io 12 
inches 
44 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
Climactichnites to an unknown animal. Malz reproduced the 
earlier illustrations of Clarke (1905) and Walcott (1912) and in 
the captions recognized two species of the genus. 
In his revision of the "Treatise," Hantzschel (1975:W-52) 
added to his 1962 comment and considered this fossil to be the 
"crawling trail of unknown producer...." He then listed all the 
various possibilities for relationship which had been proposed 
in the literature. He reproduced Clarke's sketch and two of 
Walcott's figures from the summary by Malz, thereby once 
again recognizing more than one species within the genus. 
The molluscan hypothesis has reappeared more recently. 
Runnegar et al. (1979:1382) ascribed the trail to an "aplacopho-
ran sea slug or an animal resembling Matthevia." No data was 
given to support this statement. 
Since the late 1950s, the study of trace fossils has advanced 
dramatically and paleoichnology is now a recognized specialty 
within paleontology. Many forms of ichnofossils have been 
used for paleoecological and stratigraphic interpretations. 
Some trace fossils have even gained the status of index fossils 
in correlation or as key indices for interpreting certain 
paleoenvironments. Notwithstanding all this activity, Climacti?
chnites, the largest and most spectacular trace fossil in the 
Cambrian, has remained something of a myth, a name that 
many workers have heard of, but few have seen examples of, let 
alone studied. 
Comments on Earlier Hypotheses of Origin 
Most of the suggestions as to the nature of the animal capable 
of making a trail like that of Climactichnites may be 
characterized as grouping around arthropods, "worms," or 
mollusks. However, there were other ideas expressed in the 
FIGURE 39.?A bedding plane in the Cairnside Formation at St. Hermas, Quebec (9), showing a trail of 
Climactichnites crossing over itself; the orientation is slightly different from Figure 13. Numerous desiccation 
cracks occur, best seen to the lower left of the scale. Scale is indicated by a 15 cm ruler. 
NUMBER 74 45 
^ ? i 
?x*_2 
,-^erf 
^r* 
;-' ^ ? ' \ "'" .'V'^ .'.''.? .i~,'yrfn :" ,J'?%. 
^ " ^ S C % - ? ? 5ft, H*?J* 
,
'^-
%a 
?',,(.. 'iP1, *'? f'-
FIGURE 40.?Top: Sketch of the exposure at Mooers, New York (11), from Clarke (1905, pi. 3) 'Trails on 
Potsdam sandstone, Bidwell's Crossing, Clinton co. Sketch made before removal." Clark reproduced the sketch 
at about '/28 th natural size; it is here reduced to about 'Asth natural size. The occurrence of two oval impressions 
side by side toward the left suggests that the left one-third of this area is that which is cast in plaster and on display 
in the New York State Museum. A similar plaster cast in the Brooklyn Museum was illustrated by Burling (1917) 
but is no longer extant. Bottom: Sketch of the exposure at Polly Falls, on the Black River, near Black River Falls, 
Wisconsin (3), prior to its removal, at about '/35 th natural size. Unpublished sketch courtesy of Dr. B.R. Erickson, 
Science Museum of Minnesota. 
46 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 41.?Two large trails which moved in opposite directions on a small slab of Potsdam Sandstone from 
Port Henry, New York (14). The upper is intersected and partially obliterated by another trail made by an animal 
moving toward the right, the same direction as that which made the lower trail. The trail at the lower left lacks 
lateral ridges. Unlike other specimens from Port Henry, this is the bedding plane surface. Scale is indicated by a 
15 cm ruler. MPM 27629a, on public display. 
NUMBER 74 47 
FIGURE 42.?A topotype slab from Perth, Ontario (8), showing strong crenulations. This is a sole marking, so the 
surface relief is reversed, and the crenulations on the right side are obscured by matrix remaining in the 
depression. The bars are strikingly sinusoidal. Scale is indicated by a 15 cm ruler. ROM 22171. 
48 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 43.?Latex impression of part of the same specimen shown in Figure 42. Just to the left of the scale, the 
forward prong-like extensions of the bars adjacent to the lateral ridge are similar to those on the trail from New 
Lisbon, Wisconsin (4), shown in Figure 32, which lacks the lateral ridges. Scale is indicated by a 15 cm ruler. 
ROM 22171. 
NUMBER 74 49 
FIGURE 44.?Oval impression and part of a trail probably from the Galesville Sandstone at New Lisbon, 
Wisconsin (4), figured by Walcott (1912, pi. 38: fig. 1) as C. youngi; Figure 31 is the counterpart of the oval 
impression. The irregularities on the base of the impression are as clearly shown as on the counterpart. The trail 
seemingly begins on the left, the right side possibly being smooth under an anterior flap. Major irregularity in the 
depth of furrows at the start of the trail is evident. Arched lines are seen both on the oval impression and part way 
along the trail, especially on the left side. The lateral ridges are absent, except for the faint parallel lines on the 
right. The bars are missing and the bedding plane surface may be traced from one side to the other between the 
furrows; this is particularly evident near the top of the photograph. Also, a roughed central circular marking may 
be seen on one of the bars. Scale is indicated by a 15 cm ruler. USNM 58544. 
50 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 45.?A portion of the type slab of Climactichnites wilsoni Logan, broken at one comer; this is at the upper 
left of Figure 18. The number 52 at the lower right is several centimeters below the same number at the upper left. 
On the sole marking of the bedding plane, adjacent to the scale, on the small lower triangular piece, and on the 
numbered segment, the bars are evident, and these three separate layers thereby demonstrate a dune-like buildup 
to form the bars. Scale is indicated by a 15 cm ruler. GSC 6299. 
NUMBER 74 51 
literature. The easiest hypothesis to dismiss is that of Chapman 
(1877:488-489) who suggested that for Climactichnites 
...an animal origin can scarcely be attributed on any rational grounds....If the 
impression be really a track, the animal must either have had, or been able to 
assume, the form of a complete sphere or cylinder with ribbed surface and it 
must have possessed sufficient internal force to roll itself over and over 
throughout a length of many feet; or otherwise the animal must have moved 
forward by a series of spasmodic jerks, or jumps.... 
His solution to the dilemma was to suggest that this fossil was 
not an animal, but an algal frond, a fucoid in the terminology of 
the day. Without commenting on the merits of this view, 
Chapman did not come to it abruptly, for years earlier 
(Chapman, 1862:189, fig. 157) he had mentioned Climactich?
nites and produced a small, inferior drawing of it. Today, 
Chapman's analogy of a rolling animal has been replaced by a 
rolling tire, but each assumes a regularity to the trail which does 
not exist. 
Nathorst (1881:26, translated) was withering in his scorn. 
Even tracks as distinct as the Protichnites described by Owen, and Logan's 
Climactichnites, have not escaped attempts at being drawn into the vegetable 
kingdom. To Mr. E.J. Chapman belongs the honor, a doubtful one to say the 
least, of having made this attempt, and of course it was once more algae that had 
to figure as their nearest relatives. 
Nathorst did not suggest any phylum assignment for Climacti?
chnites. 
The view of Jones (1862a,b) that the trace of Climactichnites 
might be some sort of collapsed burrow was based on his 
examination of the gallery of crustaceans living at the sea 
shore. At the same time, his reference to trilobites leads one to 
think that he might also have had in mind the notion of 
"Bilobites"?a generic name now suppressed?, a name given 
to the structure formed by the excavating activity of trilobites. 
The shape of the trace of Climactichnites, with bars and furrows 
alternating though in an irregular manner but particularly the 
crenulations of the bounding lateral ridges, argues strongly 
against there being any infaunal activity associated with the 
animal, because it is not likely that such detail could be formed 
by excavation within the sediment. The faithful reproduction of 
fine detail on part of the structure but not on another (Figure 51) 
also argues against this view. The single most telling point 
opposed to an internal burrow interpretation is the presence of 
Protichnites cutting across some trails of Climactichnites 
(Figure 55). 
Knowledge of the occurrence of Rusophycus, and other 
comparable structures which presumably were produced by 
mm.; * ? lilililr<itill|-|--il-i1l|-'-'-r-'-'-'-l,'-'V- ? ' 
FIGURE 46.?A slab from the Northern Stone Company quarry (5), showing six trails crossing slightly 
asymmetric ripple marks. The diagonal trail and the one at the lower left are quite uniform. This is a sole marking 
so the surface relief is reversed. Scale is indicated by a 15 cm ruler. MPM 28388. 
52 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
trilobites, combined with the early observation made by 
Dawson (1862) of the movements of Limulus on the beach, 
formed at least part of the basis for suggesting arthropod 
affinities for Climactichnites. Most structures attributed to 
trilobite burrowing are exceedingly short compared to the 
length of this trail, but "Bilobites" (Cruziana of current usage) 
may be as long as a meter. Size also was a consideration in the 
various suggestions about arthropods. Most trilobites are small, 
but a few specimens do approach the width of a Climactichnites 
trail. Modem Limulus is of appropriate width and some of the 
eurypterids also would have qualified in this aspect. 
The mutual occurrence of Climactichnites with the trail of 
Protichnites, which was clearly made by a limbed animal, 
further confused this issue and suggested arthropod affinities to 
some writers. However, there is no relationship between 
Protichnites and Climactichnites other than local co?
occurrence. To go to an ancillary point, the telson of limulids 
forms a drag mark impressed in the sediment; a limuloid-like 
form might well have been responsible for the trail of some of 
the species assigned to Protichnites. In contrast, a median 
marking is not a consistent feature of Climactichnites, and 
where it is present, it forms a ridge, not a furrow. 
Recently, a colleague observing our work in progress 
suggested that Anomalocaris from the Burgess Shale should be 
considered as the trail maker. This fossil, which may be an 
arthropod, has a relatively large size and paddle-like append?
ages, as well as a circular anterior mouth, all features which 
could aid in trail formation. On the other hand, it is currently 
interpreted as a predatory swimming form (Briggs, 1991:139). 
We do not consider the difference in time between Middle and 
Upper Cambrian as significant a bar to this interpretation as the 
difference between the deeper water muds and the exposed 
sands in which these two different fossils are preserved. We are 
unable to visualize how Anomalocaris might have produced a 
trail like that of Climactichnites, assuming that it crawled, for 
no part of its morphology seems to be capable of producing 
crenulated lateral ridges. The morphology of Anomalocaris has 
been dramatically reinterpreted several times during the years 
FIGURE 47.?Part of a ripple-marked slab, provenance unknown, but possibly from New Lisbon, Wisconsin (4) 
(compare with Figure 17). At the lower left, an offset of Vs and an intercalated extra half bar are shown. At the 
right, above the scale, the trail is quite irregular. Scale is indicated by a 15 cm ruler. Public display at Geology 
Museum, Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin. 
NUMBER 74 53 
FIGURE 48.?Lower left portion of a topotype slab from Perth, Ontario (8), shown in full in Figure 55. The 
Climactichnites trail to the right of the scale is highly irregular. The markings above and to the right are 
Protichnites. This is a sole marking with the surface relief reversed. Scale is indicated by a 15 cm ruler. RM public 
display. 
54 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 49.?Part of the type slab from Perth, Ontario (8), showing some variation from a wide V at the top to 
more arcuate and irregular bars below. Although the Protopaleodictyon at the right appears in normal negative 
relief on this sole marking, a trick of the lighting causes the trail to simulate a positive appearance. This is part of 
the lectotype and is shown in the lower center of Figure 18. Scale is indicated by a 15 cm ruler. GSC 6299. 
NUMBER 74 55 
FIGURE 50.?Another part of the type slab showing uniform, irregular, and sigmoidal bars; this is a sole marking, 
so surface relief is reversed. At the upper left are a few tracks of Protichnites. The precise location of this slab on 
Figure 18 is not certain, but it may be part of the trail at the left in that view. Scale is indicated by a 15 cm ruler. 
GSC 6299. 
56 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 51.?A portion of a uniform Climactichnites trail probably from the Galesville Sandstone at New Lisbon, 
Wisconsin (4). Part of this specimen was illustrated by Walcott (1912, pi. 39: fig. 2) as C. youngi and reillustrated 
by Burling (1917). An enlargement of a part of this specimen is shown in Figure 32. To the left, the arch-like 
markings are reproduced on the gentle side of the bars, but not the steep slope. This differential occurrence would 
seem most unlikely if these were markings inside a collapsed burrow. The lateral ridges are not present, though 
parallel lines appear in approximately the position of the ridge. Scale is indicated by a 15 cm ruler. USNM 58545. 
as various isolated parts have been linked together, but we think 
it unlikely that another reinterpretation will produce a 
Climactichnites-like form. 
Even though more authors suggested arthropods of one kind 
or another as responsible for Climactichnites, Walcott, who 
probably was more familiar with the limbs of fossil arthropods 
and their various modifications than any other paleontologist of 
his day, chose to ignore this hypothesis entirely and developed 
a second. After questioning any molluscan attribution for the 
trail, he (Walcott, 1912:201) suggested that Climactichnites 
might have been formed by a large worm. Walcott's comments 
coming only three years after his discovery of the dramatic 
Middle Cambrian Burgess Shale fauna were necessarily 
colored by this incredible increase in knowledge of ancient 
soft-bodied fossils. Although the specimens collected from that 
unit are too small to match the width of larger Climactichnites, 
he covered this concern by mentioning that larger forms might 
occur in younger deposits. By noting modem shallow-water 
forms, he also resolved the problem of fundamentally different 
facies of the dark shales and the sand flat. 
However, as Walcott (1912:261) wrote: "I have not seen any 
trace of bristles or stiff setae that occur on the parapodia of most 
of the Aphroditidae, but this is not unexpected in a sandstone 
formation." Considering the delicate features he described and 
illustrated on the material from New Lisbon, Wisconsin (4) 
(Figures 44,51), it seems difficult to reconcile the two thoughts 
in this sentence. Although a large, flattened, worm-like creature 
might have been able to make surface bars and furrows by 
vertical undulations of its body on damp sand, the internal 
dune-like structure of the bars could not be formed by simple 
compaction. An even greater difficulty exists in visualizing 
how any worm-like creature could form the crenulated lateral 
ridges. 
The concept of "worms" certainly involves several different 
phyla and their collective history is surely one of the least 
known aspects of paleontology. Notwithstanding that, there 
NUMBER 74 57 
l i 
300 
FIGURE 52.?A slab of Mount Simon Sandstone from Polly Falls on the Black River (5). Several trails show 
disruption near the center of the slab as though this was an area with different characteristics. The Climactichnites 
trail at the right is exceptionally wide. To the far right of the large trail and at the upper left some dewatering 
structures are present. Photograph courtesy of Dr. B.R. Erickson, Science Museum of Minnesota. Scale is in 
centimeters. SMM-P unnumbered. 
seems to be no worm-like creature in the Burgess Shale fauna 
or any other comparable fauna capable of making such a trail. 
Without being aware of Walcott's remarks, another colleague 
suggested that priapulid worms should be considered as the 
putative trail former. Priapulid worms do occur in the Burgess 
Shale fauna (Conway Morris, 1977), but they are relatively 
small specimens. Living Echiurus burrows into sand, but does 
not crawl on the surface (Gislen, 1940). 
Gratacap's hypothetical ringed worm likewise could not 
have formed the lateral crenulations, even if it had been 
discovered in the fossil record. The "worm" approach of 
Walcott has received no further support and a worm-like 
creature has simply been carried as one of a series of 
possibilities by later writers. Three-quarters of a century of 
investigation since the discovery of the Burgess Shale fauna 
has not resulted in the finding of younger soft-bodied faunas 
containing significantly larger worm-like animals, approaching 
the width of even the smallest trails of Climactichnites. 
Walcott (1912:201) dismissed part of the molluscan argu?
ment (the third prime historical suggestion for the placement of 
Climactichnites): "So far as is known to me, there is no 
recognized mollusk that would make such forward curving 
lines, and we do not know of any chiton or mollusk capable of 
making such an impression." Even though the lines mentioned 
are now known to be the result of travel in the opposite 
direction, the argument is still valid. Raymond (1922) reported 
that trails of Littorina occasionally showed an arcuate 
impression curved in the direction of movement; such a feature 
is quite rare in gastropod trails and only was seen in a few of the 
Littorina trails he studied. 
So far as we know, Woodworm (1903) was the only author 
to mention polyplacophorans, or chitons, as putative trail 
makers. It is granted that a very large modem polyplacophoran 
would approximate the width of an oval impression. However, 
although the posterior of such an impression might simulate the 
outline of the foot, the anterior of a polyplacophoran foot would 
also be arcuate and unlike the forward projecting lateral flap 
occasionally impressed in the Cambrian sandstones. Further, it 
58 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 53.?Part of a slab of Potsdam Sandstone, possibly from Mooers, New York (12); this is in the left center 
of Figure 28. The trail from upper right to near lower center shows bars, furrows, and lateral ridges. The trail from 
right to left is composed only of furrows, the bedding plane surface extending between them. Scale is indicated 
by a 10 cm ruler. PNH 98/1. 
is most unlikely that contraction of a polyplacophoran foot 
would produce the kind of ridges and furrows seen in the New 
Lisbon, Wisconsin (4) and Mooers, New York (12), impres?
sions (Figures 28, 31). Still further, large extant polyplacopho-
rans are sedentary and when they do move, this is primarily to 
graze on algae growing on adjacent rock surfaces; it is difficult 
to conjure up an abundant food source for a grazing herbivore 
on a sand flat. After foraging, typically chitons return to the 
place where they were clinging and never wander far from their 
homing spot. As an ancillary point, the largest modem 
specimens are most common in colder waters, at variance with 
the presumed ecological conditions for Climactichnites. 
Although the record of body fossils is not directly germane 
to this argument, the earliest authentic polyplacophoran parts 
are in the latest Trempealeauan, uppermost Cambrian. Matthe-
via has been considered by several authors to be a polyplaco?
phoran, but in the unlikely event that interpretation is correct, 
this form is still in the Trempealeauan and only slightly older. 
Accounts of polyplacophoran plates from the Early Cambrian 
of China seem to be based on misassignment, and belong to a 
fundamentally different type of multipartite animal (Qian and 
Bengtson, 1989). Regardless of where any of these other, older 
fossils are placed, all known plates are significantly smaller 
than the smallest Climactichnites. Indeed, the largest Paleozoic 
polyplacophoran plate is about one-third the width of the 
narrowest of the trails that we have observed. 
It may seem strange that mollusks require more in the way of 
discussion than arthropods, but mollusks do have a foot and 
arthropods do not. It is because the oval impression in 
Climactichnites mimics in part the shape of a molluscan foot 
that the mollusk hypothesis for Climactichnites is more 
difficult to dismiss. However, just as a considerable body of 
knowledge has accumulated concerning arthropod locomotion 
during the last century, information on the movement of 
mollusks has also advanced since Logan's day. In particular, 
the crawling of gastropods has been found to be more complex 
NUMBER 74 59 
FIGURE 54.?Another portion of the same slab shown in Figure 28. The trail from upper left to upper right shows 
bars and furrows but lacks the lateral ridges. The trail from lower center has lateral ridges and bars for part of the 
distance, but then only furrows; it ends abruptly. Scale is indicated by a 15 cm ruler. PNH 98/1. 
than assumed by earlier investigators. Walcott's comment on 
the presence of features resembling growth lines atop the 
pattern of bars and furrows is still the single most powerful 
argument against a gastropod origin for the trail of Climactich?
nites, but there are other features that also argue against such an 
interpretation. 
Living gastropods show both monotaxic movement, involv?
ing the entire width of the foot, and ditaxic movement 
involving first one side, and then the other. Muscular pedal 
waves may be direct, a wave of compression from the back of 
the foot forward, or, less commonly, retrograde, by waves of 
elongation from the front traveling backward (Miller, 
1974:234-238). The bars and furrows of the Climactichnites 
trail may vary at all angles from right angles to the lateral ridge 
to oblique in a V or alteration of oblique bars more or less 
around an ill-defined mid-line. Emphasis on the V partem by 
earlier workers has obscured the remarkably large amount of 
individual variation in trails. One point particularly germane 
here is the occasional insertion of a bar and furrow which are 
neither paired nor alternating. A gastropod moving along by 
regular alternation of one side of the foot or the other could not 
produce such a feature. Another point of interest is that many of 
the trails lack bilateral symmetry, for the bars and furrows may 
be longer on one side than the other, gastropod trails on the 
other hand are bilaterally symmetrical. In some large Climacti?
chnites trails, the bars and furrows are complete, but are 
strongly oblique from one lateral ridge to the other (Figure 52); 
seemingly no known gastropod foot could produce this partem. 
Although the musculature of the gastropod foot might 
provide sufficient flexibility to sculpt one or two forms of the 
trail, even the most complex musculature of Cypraea, one of 
the few modem gastropods which can move backwards, could 
not possibly produce the high degree of individual variation 
seen among trails or even along a single trail. Even more 
compelling, what is missing from gastropod locomotion is 
significant movement in the third dimension. In effect, the foot 
of a non-burrowing gastropod glides over the surface, be it 
smooth or corrugated, and there is virtually no movement of the 
60 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
FIGURE 55.?A topotype from Perth, Ontario (8), illustrated by Dawson (1890). Like the type slab, surface relief 
is reversed. One Climactichnites trail is at the lower right and another is from lower left to upper left. At least two 
trails of Protichnites are present, one at the right moving in a straight line and one at the left looping around. Scale 
is indicated by a 15 cm ruler. RM public display. 
NUMBER 74 61 
FIGURE 56.?A detail of the upper left of the slab illustrated in Figure 55. The medial ridge, here shown as a 
furrow, is irregular in position, and in width. Markings of Protichnites are at the upper right. Scale is indicated by 
a 15 cm ruler. RM public display. 
62 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
foot upward as a pedal wave moves either forward or backward. 
In effect, the distance between base of furrow and crest of bar 
in even the smallest of Climactichnites trails is far in excess of 
any vertical movement within the gastropod foot of even the 
largest of modem snails. All these peculiarities show that 
Climactichnites had a muscular system different from that of 
the gastropods. 
It is also helpful to note that movement by pedal waves of the 
gastropod foot seems to be related to dorsoventral muscular 
contraction and relaxation, implying that attachment to a shell 
is needed for such waves to develop (Kier, 1988:239). Many 
gastropods also move by ciliary action on the sole of the foot 
and such gliding motion is best suited to movement over a 
loose sand substrate (Miller, 1974:254). This form of motion is 
far less likely to cause any compression of the substrate than are 
muscular pedal waves. 
Abel (1935:247-248) emphasized Bulla-Wke gastropods 
forming a ridge on either side of the shell as they crawl forward. 
Some snails, such as Polinices do plow through the sand as 
essentially infaunal animals, with the shell below the surface or 
protruding just above the sediment-water interface; the large 
foot moves particles to either side as the animal in effect glides 
forward. This disturbs the sediment but it is unlike surface 
plowing which produces lateral ridges on either side of a central 
smooth depressed zone. Those ridges are in effect tossed up in 
a manner that is quite unlike the piling up of sediment to form 
a lateral ridge without disturbing the substrate. 
Other gastropods, like Littorina, which Abel figured, do 
move effectively on the surface by retrograde waves. "The foot 
progresses somewhat in the manner of a person slowly 
shuffling forward in a potato sack" (Abbott, 1954:453). Neither 
Abbott nor Abel reported any faint transverse ridges oriented 
convex forward, as Raymond (1922) noted occurred rarely. 
This surface movement of Littorina also forms lateral ridges 
because the lower part of the foot is within the substrate. 
However, in neither the case of the animal virtually covered by 
sediment or the foot just within the substrate do the lateral 
ridges, which are produced, exhibit crenulations that are 
characteristic of many specimens of Climactichnites. More 
importantly, the area between lateral ridges is smooth, not 
undulatory. 
On a more theoretical level, pedal wave movement, which is 
best adapted to a hard substrate, is considered the earliest form 
of locomotion in gastropods, ciliary movement being a later 
development (Miller, 1974:234). It is difficult to reconcile 
advanced forms of gastropod locomotion with early gastro?
pods, though admittedly excessive concern with theory is not 
always helpful. From the practical standpoint, trails of some 
gastropods are common on mud flats where an abundant food 
supply is present, but they are rare on sand flats. In the fossil 
record almost none of the markings which past generations of 
paleontologists attributed to gastropod trails occur in environ?
mental settings where gastropods might have lived. 
Another major problem with a gastropod hypothesis for 
Climactichnites is the width of the fossil trail. Modem large 
marine gastropod shells have an apertural opening which 
approaches the width of a small Climactichnites trail, and very 
large gastropods could occupy the width of a moderate-sized 
track. However, no known gastropods, either living or fossil, 
would have a foot as wide as the width of the widest trails 
(Figures 3, 7). 
As with the other hypotheses, the absence of body fossils 
may not be germane, for it has been repeatedly argued in the 
past that no shells have been found with the trails because they 
were either destroyed by sediment motion or moved away by 
tidal activity. Negative evidence such as this is impossible to 
refute, but it is difficult to imagine water movement strong 
enough to sweep away a large heavy shell, yet gentle enough 
not to disturb a trail. 
As with the Polyplacophora, the evidence of body fossils 
also speaks against assignment of Climactichnites to the 
Gastropoda. The age of the earliest example of this class is 
currently a source of considerable argument, but if there were 
any gastropods in the Early and Middle Cambrian, all fossils 
now assigned by some authors to this group are in the range of 
1-2 cm maximum width of the shell. More likely, the earliest 
gastropods occur near the Dresbachian-Franconian boundary. 
The largest examples of this age are known to have a maximum 
apertural width of 3 cm. It is not until late in the Ordovician that 
the aperture of a large Maclurites would approximate the size 
of a small Climactichnites trail, and there is considerable 
uncertainty as to whether this snail crawled (Yochelson, 1990) 
The opisthobranch hypothesis is difficult to grapple with, for 
it too is based on lack of evidence. Obviously a non-shelled 
gastropod is unlikely to leave much of a fossil record; consider, 
for example, the potential number of soft-bodied coelenterates 
that might have been in the Cambrian seas and how limited a 
record remains of them. What little is known of the early 
shelled opisthobranchs suggests that they did not appear until 
the mid-Paleozoic (Kollmann and Yochelson, 1976). The best 
modem model for any hypothetical animal among this subclass 
of gastropods would be the "sea hare" Aplysia, for large 
specimens are large enough to have filled an oval depression of 
Climactichnites. However, an exceptionally large specimen 
may weigh 2 kg, hardly enough to compact sand by its weight. 
Living Aplysia are best known for swimming, but when they do 
crawl, it is most often on clumps of marine grasses and only 
rarely on sand flats. In the instances in which a living animal is 
stranded on a beach by an abnormally high tide, the body 
essentially collapses under the force of gravity and the 
opisthobranch does not attempt to get back into the water (Dr. 
R.T. Abbott, oral communication, 1990). 
To summarize, we are not convinced that Climactichnites is 
to be associated with any platyhelminth, annelid, or any 
"worm-like" animal. We are equally convinced that no living or 
fossil representatives of Arthropoda or Mollusca was capable 
of producing the trail of Climactichnites or is anyway related to 
it at the level of phylum. 
NUMBER 74 63 
Alternative Hypotheses 
No one simply gathers facts and makes observations blindly 
in the hope that clarification and insight will automatically 
result from this process. Each of us started this investigation 
with a hypothesis, and each ultimately rejected it, but these 
notions served to stimulate discussion and observation, and 
each contained at least a kernel of useful ideas. 
Yochelson first became aware of Climactichnites 40 years 
ago and for more than 30 years at occasional intervals looked at 
the large slab on display at the National Museum of Natural 
History (Frontispiece). His notion was that the animal which 
formed this trail was unlike any known in the Paleozoic and 
that it had been swept beachward by unusually high water, 
there to struggle in its attempt to return to the sea. The 
discovery in the 1940s of the late Precambrian fauna from the 
Ediacara Sandstone in Australia, containing forms unlike any 
others in the fossil record, seemed to reinforce this view of an 
animal unlike any other. Further, Climactichnites seemed to be 
a rare fossil, and the random directions of movement on this 
slab might be interpreted as the struggle of an animal under 
duress. Finally, the kidney bean shape of impressions, as then 
known, suggested the asymmetry which appeared to be present 
in some specimens of the Precambrian fossil Dickinsonia. 
On the other hand, Fedonkin was unfamiliar with Climacti?
chnites, except as a name in the literature, until 1989 when he 
had the opportunity to briefly examine the large slab at the 
National Museum of Natural History. A few features observed 
thereon, combined with his field studies on three continents of 
the preservation of Precambrian biotas, and on more character?
istic early Paleozoic trace fossils, suggested to him that this 
fossil might be interpreted as the imprint of an animal, rather 
than as a trail. Elongated frond-like organisms having a 
sympodial mode of growth are prominent members of the 
Precambrian animal community. In the framework of this 
hypothesis, the "kidney bean-shaped" body at one end of some 
trails could be interpreted as a pneumatophore that carried an 
elongate, band-like colony of polyps similar to pelagic Recent 
hydrozoans, specifically siphonophores. Because some of the 
these colonial organisms have tentacles reaching 20-30 m in 
length, and thus are even longer than the known trails of 
Climactichnites, this idea could not automatically be dismissed. 
As a variant on this hypothesis, consideration was also given 
to the notion of a long ribbon-like animal lying on the bottom 
in shallow water. The discoveries in the Late Precambrian 
Vendian and the "soft-bodied" Lower and Middle Cambrian 
faunas have emphasized how little we know of possible body 
plans and locomotion strategies developed in the past. 
Our original notions presented above, like those discussed 
by earlier investigators, are not supported by morphologic data 
and have been abandoned. 
Paleoecological Interpretation of Climactichnites 
At some localities, Climactichnites is the only fossil 
observed. In particular, in the Wisconsin outcrops and museum 
specimens, we saw no clear evidence of other organic forms. 
The slab at the University of Wisconsin-Madison may bear 
poorly preserved Protichnites, but the markings are equivoca-
ble; Raasch (1939:7) mentioned Protichnites in Wisconsin, but 
provided no details. In 1990, Mr. W. Nemke found Protichnites 
in the Northern Stone Company quarry (5), though not on the 
same bedding plan with Climactichnites. 
The type slab from Perth, Ontario (8) (Figure 18), bears 
abundant Protichnites and the network trace of Protopaleo-
dictyon. At St. Hermas, Quebec (8) (Figure 9), and at 
Keeseville, New York (13), Protichnites occurs both with 
Climactichnites and on adjacent bedding planes above and 
below this fossil. In the Port Henry, New York (14) material, 
Protichnites is present on some slabs but not on others. We 
have not observed shelled invertebrates either on the same slab 
or in outcrops with Climactichnites. Inarticulate brachiopods 
are reported from slightly younger Dresbachian beds, often 
from the same sections which yielded Climactichnites. 
"Tube" dwelling fossils, such as Skolithos and Dip-
locraterion are absent, though like the inarticulate brachiopods 
and rare trilobites, they do occur higher in the section in other 
sandstone units of the areas studied; presumably these 
tube-bearing sandstones were deposited in a lower tidal flat 
facies. The absence of Climactichnites in a slightly deeper 
water facies that was more favorable for the presence of 
tube-dwelling bioturbators poses the question of whether this is 
a coincidence or instead reflects environmental differences. We 
had earlier concluded that Climactichnites lived in the harsh 
peritidal environment where its trails are found. In present-day 
ecologically high-stress environments, diversity is limited but 
the number of organisms locally present may be quite high. 
This general rule certainly applies to the fossil under study. 
Considered on a different level, the absence of any indication of 
Climactichnites in the less harsh, slightly deeper water facies 
might mean that it was never present, or alternatively that it left 
no indication of its presence. Like so many of the points with 
this fossil, this question of where it lived when it was not 
crawling on a sand flat remains an enigma. 
The common joint occurrence of Protichnites and Climacti?
chnites in Ontario and Quebec suggested to a few of the early 
investigators that they might have been markings made by the 
same animal. The distinction between them is now clear and 
Protichnites is generally attributed to an arthropod. In the 
instances of co-occurrence, the trail of Protichnites cuts that of 
Climactichnites. If our interpretation of the environment is 
correct, Protichnites is well adapted to life on a beach rather 
than to a marine environment. Without any proof, we offer the 
suggestion that some essentially soft-bodied Climactichnites 
could have fallen prey to this faster moving organism. No small 
Climactichnites are known and a carnivorous Protichnites 
would provide one possible explanation from their absence 
from the fossil record. 
If conditions on a sand flat with fluctuating water levels were 
64 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
harsh, and perhaps also a predator was present, one may ask 
why Climactichnites occurred there. A logical suggestion is 
that the animal was exploiting a food resource. In this 
connection, we note that recently the record of foraminifers has 
been extended backwards by identification of ammodiscid 
foraminifers in the Early Cambrian (Culver et al., 1990). Naked 
protists would leave no record and agglutinated foraminifers 
could not be identified in an indurated sandstone; this 
discovery of Early Cambrian agglutinated foraminifers re?
quired a unusual set of circumstances. On the Late Cambrian 
sand flats, both agglutinated and naked protists could have 
abounded in the uppermost layer of sediment. Warm moist 
conditions would have been ideal for photosynthesis of 
symbiotic algae. By comparison to extant protists, probably 
they would not have penetrated much more than a centimeter 
into the sand, even when the tide was low. 
Feeding Behavior 
The abundance of Climactichnites trails and details of their 
morphology led us to the view that the trail represents 
purposeful behavior by the animal. Of the various activities that 
an animal performs, food gathering is fundamental and we 
consider this the prime reason for formation of most trails. 
In a tidal environment such as we have interpreted for this 
fossil, the time of high water brings in the most suspended 
sediment, which then settles to the bottom. The troughs of 
ripples tend to trap fine clay-sized particles, which are richer in 
occluded organic material than the sand. Although this physical 
phenomenon is an important feature of the habitat for some 
living forms and probably for other detritus-ingesting fossils, 
we are not convinced that Climactichnites fed by collecting 
organic debris from the upper surface of wet sand. A strong 
argument against this interpretation is the cross-cutting 
relationships of trails to ripples where they are present (Figures 
8, 37). Many specimens of Climactichnites do not occur on 
rippled bedding planes, but even in the instances of ripples, not 
all trails reach the trough of the ripple. Were the animal seeking 
the organic matter in ripple troughs, the directions of trails and 
ripples would be parallel; although this does occur, it is very 
much the exception rather than the rule. Indeed, if Climactich?
nites was primarily concerned with collecting organic matter 
concentrated in mud, one would expect that the fossil would be 
most abundant on mud-rich substrates, rather than sand flats. 
Rather, we propose a novel feeding mechanism for this 
unusual animal, based in part on the features of the trail that it 
left. A critical detail seen in the New Lisbon, Wisconsin (4), 
specimens (Walcott, 1912) is the presence of fine, arched lines 
on the sole of the animal. These occur within the oval, crossing 
the irregularities of that surface and continue onto the bars and 
furrows, being seen best on the gentle slope of the bars (Figure 
44). These lines may also occur on the slab from Beauharnois, 
Quebec (10), though the coarser matrix at that locality makes 
their presence more equivocal, and they cannot be documented 
by photography. 
The arch-like impressions superficially resemble the growth 
lines which occur on the shells of invertebrates, but it is 
difficult to imagine why prominent growth lines would occur 
on the relatively soft and deformable sole of the animal and 
why they would be reflected on the sediment surface. A more 
plausible interpretation is that these lines were the sites of rows 
of cilia on the sole of the animal. Cilia should have been 
sensitive enough to gauge the water content in the substrate. In 
addition to thigmotaxis or thermotaxis sensing, the cilia might 
have had a chemotaxis component to evaluate the amount of 
protoplasm within the upper layer of the sand. 
If our interpretation of locomotion is correct, anterior and 
lateral clamping of the animal to the damp sand developed a 
slightly different microenvironment under the sole, probably 
lowering the cohesiveness of the sand particles. The rows of 
cilia moved the upper layer of sand forward, brushing it against 
the anterior of the animal to form the upper part of the bars and 
digging in a slight distance to accentuate and deepen the 
furrows. The shape of bar and furrow, having a steep anterior 
face and gentle posterior slope, is comparable to that to the 
shape of a sand dune, and the mechanism of movement of the 
fine sand is similar. It is to be emphasized that the primary 
shape of the bars was formed under the anterior flap as its 
forward edge dug into the substrate to form a furrow and then 
contracted. The more gentle brushing action of the cilia added 
several inclined laminae to the mound of material; this is why 
the bars and furrows are more or less straight, not arcuate, 
below the fine arcuate lines. On the other hand, arcuate lines of 
cilia would be the appropriate shape for transporting selected 
particles laterally toward the center of the animal. 
By brushing the sand with cilia on the sole of the animal, 
microorganisms in the first few millimeters beneath the surface 
would be exposed and forced forward. In addition, the 
formation of oscillation ripples by wind action disturbs the 
surface of the sand in the same manner as would the presumed 
cilia on the sole of the animal. It may be no coincidence that 
Climactichnites appears to be more abundant in ripple-marked 
sandstone, for if the feeding mechanism we suggest is correct, 
the microorganisms would have concentrated in the ridges of 
the rippled sand. Although there is no evidence in the fossil 
record as to when a meiofauna as it is known today evolved, it 
is not necessary for our hypothesis that a meiofauna was 
present in these Late Cambrian sand flats. From what is known 
of the life habits of extant benthonic foraminifers, it is likely 
they would have swarmed in the warm moist environment of a 
Late Cambrian sand flat; as noted, the occurrence of foraminif?
ers in rocks older than Late Cambrian has been documented. 
The theoretical mode of completing bar formation by 
brushing sand forward from the posterior had been considered 
prior to our examination of the Port Henry, New York (14), slab 
in the American Museum of Natural History (Figure 35). For 
this hypothetical feeding mechanism to work, it would require 
NUMBER 74 65 
a mouth on the sole of the animal to ingest the organisms 
collected and concentrated from the sediment, and then 
transported toward the center of the body. Otherwise enigmatic 
marks, located at the center of the trail, are in the correct 
position. When compared with Anomalocaris, for example, 
they are also of the proper general size and shape to suggest 
impressions of a mouth. The concentric circles on the 
Beauharnois, Quebec, slab (Frontispiece), consisting of a ring 
of low relief enclosing another (Figure 34), are of the same size, 
as are others from Port Henry, New York (14) (Figure 36) and 
New Lisbon, Wisconsin (4) (Figure 44). 
An elongate worm-like form burrowing either vertically or 
horizontally would have two alternative feeding mechanisms. 
Either the animal moves through the sediment or the sediment 
moves through the animal. In either case, the consequence is a 
trail of disturbed sediment that has largely or wholly been 
moved through the digestive tract of a creature. If Climactich?
nites was a major sediment processor, a continuous large string 
of sediment-rich fecal matter would be a feature to mark its 
forward progress. Nothing like this modifies the bars and 
furrows. Rather, on a few specimens, traces of an irregular 
ridge occur between the bounding lateral ridges. Such medial 
ridges vary in strength, in position, and in their presence along 
a single trail (Figure 18). We interpret this ridge as a relatively 
fine fecal string. Climactichnites would necessarily ingest some 
sediment along with the concentrated protists and then have to 
excrete it at irregular intervals. 
Locomotion and Trail Formation 
It is evident from the oval impressions that Climactichnites 
lay at least partially covered by sand prior to moving upward 
and beginning to make its trail. Burrowing in the sediment has 
the obvious advantages of protection from possible predators 
and shading from increased ultra-violet radiation as water 
shallowed during the tidal cycle. We have not observed any 
trails leading to an oval impression, only those crawling away 
from it. If the animal had lateral flaps, they may have assisted 
in shallow burrowing under water, as they do in the activity of 
rays and skates. 
In our view, Climactichnites was a swimming form during 
part of its daily cycle. It moved by manipulating a pair of 
undulating lateral flaps, discussed below. This movement may 
not have been a particularly graceful or extended method of 
traveling through the water column?comparison with the 
effective but seemingly inefficient movement of pectinacean 
pelecypods when movement is needed comes to mind. It 
would, however, have been sufficient to permit the animal to 
settle onto a sand flat during a falling tide and, later, swim away 
on the rising tide to rest on the bottom in deeper, cooler water 
when the flat was again awash and feeding terminated. Whether 
the animal was capable of such movement through the water 
may never be resolved, for it is founded on the assumption of 
the presence of lateral flaps, a feature that seems reasonable 
from the trail formation, but one that cannot be conclusively 
proven in the absence of soft parts. 
Instead, we concentrate on the problem of trail forming. The 
relatively high bounding lateral ridges and the depth of furrows 
originally suggested to us that the animal was plowing through 
the upper level of the sediment, not gliding over the sand 
surface. This plowing appearance is particularly striking where 
a trail cuts through a ripple mark, for there is essentially no 
lateral disturbance of a ripple crest adjacent to a trail. However, 
anyone who has ever molded a structure out of damp sand will 
immediately recognize that the pushing of water soaked sand is 
extremely difficult and requires a large amount of energy. 
As a result, our original notion that the animal pushed 
through the sand by means of a dorsoventral locomotionary 
wave was soon abandoned. A person standing on damp sand 
has about the same surface area in contact with the sediment as 
would the animal, but has a far larger body weight. We found 
it impossible to reconcile the apparent depth of plowing, no 
matter how slight, with the weight and musculature that would 
be needed for this activity. We were thus led to the view that 
basically the trail was built on the surface of the sediment, a 
point later proven by discovery of the internal dune-like 
structure of the bars (Figure 45) 
Yet another consideration against any plowing of the 
sediment is the bars and the furrows themselves. If the animal 
had more than one locomotionary wave to move it forward, the 
motion of the later ones would destroy or strongly modify any 
internal structure of the trail. The presence of fine arched lines 
on the bars (Figure 31) argues against any such significant 
modification once the basic shape of these structures was 
established. 
Having been the first person to find any indication of the 
beginning or end of a trail, Woodworm (1903) was also the first 
to have any basis for an attempt to analyze the direction of 
movement. He concluded that the oval impressions marked the 
end of the trail. Apparently, Walcott (1912) concurred with his 
interpretation for on the caption of plate 38 of his work, he 
noted: "Forward arching lines on the transverse ridges made by 
backward push of the animal in creeping forward." Thus, the 
interpretation of Burling (1917) that movement began at the 
oval impression was a dramatic change. 
Confirmation that the impression marked the start of the 
trail, not the end, was provided by Clark and Usher (1948) with 
their sketch of a trail crossing over its earlier portion (Figure 
38). The V of the bars points toward the origin of the trail. The 
short turning radius of the animal when a trail crosses itself 
(Figure 39) not only supports the concept of a short compact 
body, but one that had some sort of internal support, perhaps 
cartilage, perhaps an elaborately musculated hydroskeleton, so 
that it did not change width when curving strongly. The force 
required to form the lateral ridges would seem to tip the balance 
in favor of strong muscles. In other words, Climactichnites did 
not deform like an earthworm during its movement. 
The overall bilateral symmetry of the oval impressions is far 
66 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
from perfect, for in the few examples available one side or one 
end is deeper (Figures 25, 26). We infer that the sole of the 
animal wiggled a centimeter or so up the surface of damp sand 
and that slumping or compaction modified the imprint. A 
special problem is presented by several oval impressions which 
are flat and appear to be on the bedding plane, not below it 
(Figures 27, 34). The animal might have come to rest on the 
sand bottom after swimming and then moved back into the 
water column without crawling because the texture of the 
bottom at that spot was not satisfactory. Alternatively, the 
sediment surface may have been scoured and these oval 
impressions remain because they were a few centimeters below 
the surface. Insufficient information is available to choose 
between these two hypotheses. 
The bilateral symmetry is not so evident at the anterior part 
of the oval impression. Even though few oval impressions are 
known, one has an anterior smooth area to the left side of the 
animal (Figure 28), one has a similar area to the right side 
(Figure 26), and one appears to have a triangular, relatively 
smooth area along the axis of bilateral symmetry (Figure 20). 
From this, we infer that the animal extended an anterior flap, 
found purchase against the damp sand, and pulled itself 
forward, undulating the sand surface under the flap. Subse?
quently, it put forward a flap on the other side and repeated the 
motion. This would allow for the formation of the V shape to 
the bars. Because the flap was more constrained medially near 
the anterior than laterally, the result of muscle contraction 
would move sand so that the bars would be inflected toward the 
posterior. 
Individual variation in the flaps, combined with local 
variation in the substrate, thus provides the raw material for the 
considerable amount of variation seen along one trail and 
among trails. A few trails show a nearly complete obliquely 
inclined bar, rather than a V (Figures 42,53). In these instances, 
for some reason, the animal concentrated all its effort on one 
side; as suggested earlier, this might be rapid locomotion 
without feeding. In no way does that conflict with the concept 
of a coelomic pouch and a hydroskeleton to help direct the 
various muscles. 
Forward movement was slight during feeding, perhaps on 
the order of about 5-10 mm with each extension of a lateral 
flap. Having pulled itself forward, the animal then used lateral 
flaps to clamp onto the sediment by moving sand inward 
parallel to the body. This lateral clamping require musculature 
at least as strong and probably stronger than that in the anterior 
flaps. To summarize, we infer that forward movement was a 
four stage process consisting of: forward extension of an 
anterior flap on one side and pulling forward of the body; 
lateral clamping in the new position and relaxation of the 
musculature in the anterior flaps; lateral expansion of the other 
anterior flap and pulling forward; and lateral clamping and 
relaxation of the anterior. A close connection between 
presumed anterior flaps and presumed lateral flaps is shown by 
the small lower structure adjacent to the lateral ridge and 
anteriorward of the bar (Figure 43). More or less simultaneous 
with these movements, cilia on the sole brushed sand forward, 
moving organic material toward the central mouth of the 
animal, and sand particles onto the bars to complete dune 
formation. 
Where the lateral ridges cross ripple crests, the contact of the 
two is relatively sharp (Figure 22); there is no area of disturbed 
sediment between ripple crest and lateral ridge. The implication 
is that the anterior part of the animal cut through the ripple 
mark before the lateral ridge formed, as our hypothesis 
demands. A trail may curve gradually, but it does not weave 
from side to side. Lateral clamping and sediment ridges 
extended most of the length of the animal to prevent such 
irregularity. 
Both smooth and crenulated lateral ridges (Figures 17, 18) 
occur and we attribute this difference to the condition of the 
sand and the muscle tension requirements of the animal at the 
instant of ridge formation. We take the absence of lateral 
bounding ridges on some trails to be a result of their secondary 
removal by sedimentary processes. Although there are bars and 
furrows without lateral ridges, we know of no examples in 
which the ridges remain and the interior features are gone. 
The presence of a continuous line of bars and furrows 
between the lateral ridges effectively destroys any notion that 
the trail was made by plowing activity. It also imposes 
considerable restraint on any constructional hypothesis, for 
either bars and furrows were formed entirely by the posterior of 
the animal or somehow the animal could move over the 
anteriorward constructed bars and furrows without modifying 
them to any great extent. We judge the latter to be much more 
probable. 
Perhaps the most remarkable feature of Climactichnites is its 
excellent preservation in an environment where preservation is 
most unlikely, as a result of repeated movement of the 
sediment. Most surface trails, in the early Paleozoic at least, 
occur in environments characterized by slightly deep quiet 
water and "event" movement of sediment to bury them, rather 
than periodic shifting of sands. The amount of local sediment 
transport on a mud flat is far less than on a sand flat, and seldom 
are modem-day trails preserved on a tidal mud flat. We suggest 
that secretion of mucus would aid in preservation of the trail. 
Production of large amounts of mucus probably was the reason 
that Climactichnites could move over the sand and compress 
the damp particles without the sharp particles wearing away its 
body tissue. A mucus-covered trail would also explain how an 
animal was able to move over bars and furrows without 
destroying them. Ciliary action on the posterior part of the 
animal rather than waves of muscle contraction would also help 
preserve the trail from modification. 
Our proposal for movement of the animal, ignoring the 
morphology of the constructional trail, resembles that of the 
"inch worm" whereby the anterior moves forward and attaches 
to the substrate, the body then moves forward and the posterior 
attaches, allowing the anterior to move forward again. Such 
NUMBER 74 67 
locomotion is quite efficient and a tiny animal may move more 
than 3-4 cm in less than a minute. 
Speculation on the height and the duration of tides in the 
Late Cambrian epicontinental seas must be uncertain, but a 
plausible assumption is that slack low water probably was in 
the range of one to two hours. Evaporation toward the end of 
this period might have been partially compensated by a rising 
water table as the tide increased, particularly if the tidal 
amplitude was low. Thus, the moisture of the sand should have 
remained nearly constant or varied within small limits. The 
longest Climactichnites trail known is about 4 m, and there is 
no trace of a beginning or an end. Notwithstanding that further 
uncertainty, in a two hour interval this would require the animal 
to travel at a rate of slightly less than 4 cm a minute. Such a rate 
would appear to be reasonable for the mechanisms that we have 
proposed, both for locomotion and for feeding. 
Climactichnites and the Early Ichnological Record 
The stratigraphic interval of the Vendian and the Cambrian 
is characterized by a rapid increase in diversity, morphologic 
complexity, and size of bioturbators. This increase is demon?
strated by different traces emphasizing various activities, 
preserved in rocks recording shallow marine environments. 
During this same time, there ensued a change from essentially 
a two dimensional pattern of paleoichnologic activity to a three 
dimensional one. This phenomenon is related to penetration 
and colonization of the subsurface, that is the transfer of 
activities for some animals from on the sediment surface to 
within the sediment (Fedonkin, 1977, 1981). 
Near the close of the Cambrian Period, the degree of 
biological processing of sediment seems to have reached its 
critical point as a result of niche partitioning in the shallow 
marine shelf environment. The ichnocoenoses of the Vendian 
and much of the Cambrian contain typical shallow water forms, 
such as Bergaueria and Skolithos, along with more morpholog?
ically complex and diverse trails and burrows; the latter are 
characteristic of deeper water facies in the younger part of the 
Phanerozoic record. It is difficult to apply the excellent model 
of bathymetric zonation of trace fossil developed by Seilacher 
(1967) to this more ancient admixture of forms. 
Apart from the Cambrian grazing trail Oldhamia, which may 
have lived in a deeper marine environment, few of the 
Vendian-Cambrian traces occur in deep water sediments. 
Active colonization of this habitat did not begin until the Early 
Ordovician (Crimes, 1974, 1992), reflected in a dramatic 
increase in diversity of bioturbation. During the same interval, 
in the shallow water environment, the diversity of trace fossils 
appears to have remained constant or perhaps even decreased 
slightly. 
There are at least two possible interrelated reasons for 
movement of bioturbating organisms to deeper water environ?
ments. First, there may have been an increase in population 
density of the bioturbators, and second, there may have been an 
increase in diversity of new predators in the shelf environment. 
It is important to note that the penetration of the deep sea by 
bioturbators was a shift in environment that was not accompa?
nied by any obvious major change in morphology, for the 
features of the traces involved in this ecological shift remained 
constant. 
Climactichnites also left the shallow marine environment, 
but moved up slope, not down. In contrast to the bioturbators 
who descended down into deeper water, Climactichnites was 
forced to adapt to a dramatic change in habitat. The 
environment on the sand flats was very much harsher than that 
of deeper water. Among the most obvious problems were those 
of drying out and of gravity, difficulties not encountered in the 
aquatic realm. Less obvious, but equally present, were the 
dangers of higher temperature, excess oxygen, and ultraviolet 
light. 
Climactichnites was a pioneering type developing a different 
body shape to compensate for the pull of gravity and a different 
mode of life to utilize a new food source. As such, its 
adaptation was far more remarkable than those of the 
bioturbators who had moved downslope. The tidal flats served 
as a staging area and barrier between sea and land, but one in 
which essentially no fossil record is preserved. Understanda?
bly, Little (1990) begins his brief account of the development 
of terrestrial ecosystems with the reputed terrestrial forms in the 
Ordovician and does not consider earlier time (see also Gray 
and Shear, 1992). To our mind, Climactichnites is remarkable 
in showing a first attempt to cross this barrier. In the sense that 
this did not lead to permanent colonization of land, it was a 
premature attempt. 
From a more theoretical standpoint, the pioneer phase in the 
evolution of communities is considered to be related to trophic 
flexibility and large body size, as it is reflected in the record of 
trace fossils (Seilacher, 1977). To some extent, a large body 
may represent the phenomenon of "reserve biomass" which 
allows an animal to survive in extreme situations of an 
environment characterized by unstable food resources (Pono-
marenko, 1984). Climactichnites and its occasional fellow 
traveller Protichnites seem to be organisms which fit this 
theory. 
Seilacher (1977:374-375) briefly described a meandering 
pattern made on putative Late Cambrian rocks of Saudi Arabia, 
which he attributed to gastropod grazing tracks, an interpreta?
tion based on presumed radular bites and scratches. He 
compared this material to Climactichnites, from the standpoints 
of age and paleoenvironment. McMenamin and McMenamin 
(1990:124, 125) reproduced part of the sketch of Clarke (1905) 
and extended Seilacher's argument further, suggesting that 
Climactichnites was exploiting bacterial mats to the very limits 
of their ecological niche and grazing them to extinction. Except 
perhaps in the case of an exotic predator introduced onto a 
small island, we can think of no case in which a predator might 
eat all of its food supply and thereby also become extinct. 
Climactichnites does not exhibit any evidence of a radula, nor 
68 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
is there any direct or indirect evidence of its grazing on a 
surface mat; bacterial mats are still extant. 
Reconstruction of Climactichnites 
Burling (1917:397) assembled a solid foundation of facts to 
arrive at a "flexible slug-like animal which was frequently 
stranded at low-tide, but was able to swim in the waters of full 
tide...." We have had the benefit of observing many more 
specimens of this fossil combined with access to more than a 
half century of ancillary data on sedimentation and marine 
biology, along with a somewhat different approach to 
evolution. We are not in conflict with Burling so much as we 
are grateful to him for providing a solid base from which we 
started our reconstruction. 
Although many of our inferences concerning Climactich?
nites have been presented already, by way of a summary, we 
shall repeat some of the conclusions. Climactichnites was a 
triploblastic, bilaterally symmetrical animal. The ventral part 
was a strongly muscled foot, but with considerable flexibility; 
the thick skin of a large mammal perhaps provides a rough 
analogue of its characteristics. At least part of the sole in the 
posterior portion of the animal was covered with rows of cilia, 
arch-like in arrangement and with curvature following that of 
the posterior margin of the creature. The organism was perhaps 
twice as long as wide, and more or less lozenge-shaped. 
Because of the tough integument, strong muscles, and perhaps 
some sort of internal cartilaginous structure, the body retained 
its shape during movement. 
The animal was low and broad, flattened more toward the 
posterior. A large form was perhaps about 5 cm high. The 
dorsal surface of the creature was modified into two large flaps 
of musculated tissue which hung down on either side of the 
animal extending a few centimeters out over the sediment when 
fully relaxed. These were intermittently compressed against the 
sides of the animal. 
Because of the problems of heat and evaporation on an 
exposed sand flat, whatever kind of breathing apparatus the 
organism possessed, it was likely to be covered by these flaps, 
rather than exposed on the dorsum of the animal. The sole of 
the animal, the sides, and least the lower surface of these strong 
prehensile flaps probably produced great quantities of mucus, 
that coincidentally helped to preserve its trail in the damp sand. 
Climactichnites probably gathered microorganisms from the 
upper few millimeters of the sand by brushing the surface with 
cilia. Particles of food were selected and moved along the 
curved, ciliated tracks toward a mouth located somewhere on 
the sole. A digestive track ran from the mouth to posterior anus. 
At irregular intervals, the organism discharged some of the 
ingested matrix as a fecal string. 
During feeding, the animal moved forward spasmodically, 
but more or less continuously. Its anterior had two large 
strongly muscular flaps of tissue, approximately triangular in 
shape. The outer edge of each flap extended laterally and was 
approximately parallel to the sides of the animal. One of the 
FIGURE 57.?Schematic interpretation of the movement of Climactichnites. 
Phase 1: The right side of the anterior of the organism has expanded as a 
wedge-shaped flap, dug into the substrate, and pulled the main mass of the body 
forward. Phase 2: The lateral flaps have compressed, pulling sand inward and 
holding the body in one place. Phase 3: The main mass of the body is still being 
held in place by the lateral flaps, though not so tightiy, and fluid is being 
transferred from the right side of the anterior to the left side. Phase 4: The left 
side of the anterior of the organism has expanded forward, dug into the 
substrate, and pulled the body forward. Arrows indicate general movement, not 
the precise direction of the pull of complex musculature. 
angles of each triangular flap attached near the mid-line of the 
animal. The flaps were extended alternately to grasp the 
sediment and pull the main part of the body forward. Between 
each forward movement of an anterior flap, the animal 
compressed the lateral flaps to hold it in place while anterior 
muscles relaxed for the next forward movement (Figure 57). 
To regulate this complex movement of muscles, the nervous 
system was highly developed. As one method of mitigating the 
harsh environmental conditions of the sand flat, the animal may 
have been nocturnal or crepuscular, moving only during times 
of low light. If this supposition is correct, the animal possessed 
NUMBER 74 69 
1 
"?*? ?<*',? ?? ??? ?? W M k * < , . . * .'?-*- < .^v ' - - ' . - ' ' T . . . ' ^ 
' *'^**''*^?>mnamimiiii!ifir 
^KTJrflli> 
J # 
FIGURE 58.?Drawing of Climactichnites in life. To the lower right, one animal is moving, using most of the 
anterior edge to pull itself forward; compare the trail with the upper part of Figure 14 or Figure 52. It has just dug 
into the substrate and the lateral flaps are still relaxed. The animal near the center is proceeding by extending 
alternate sides of the anterior edge, as is more characteristic. It has already moved forward, and even though the 
lateral flaps still grasp the sand pulled inward, the animal is in the process of transferring fluid to the left anterior. 
To the far right of its trail is an irregular median discharge of sediment within the lateral ridges; compare with 
Figure 19. The organs near the anterior of the animals sense the low level of light and, hence, the relative cool 
temperature of the exposed sand flats at night. Not seen on the two animals is the ventral mouth and cilia piling 
sand up into small dunes between the furrows dug by the ephereral anterior extensions. In the immediate 
forground is the posterior portion of a resting impression, showing the traces of fine lines which bear rows of cilia 
to sweep sand into dunes beneath the sole of the animal; compare with Figure 31. Several other impressions of 
the sole and of animals crawling are in the middle distance. Many individuals crawl over the sand flat or have 
crawled away. Reconstruction by Mary Parrish. 
some kind of dorsal light receptor. 
As reconstructed, Climactichnites has morphology which in 
part was not unlike that of modem marine skates and rays. 
These animals swim by undulations of the flattened body and 
rest by burrowing shallowly into a sandy bottom. If Climactich?
nites could swim, it was not so efficient as these graceful, more 
streamlined forms. The principal physical activity of this Late 
Cambrian fossil was to move on damp sand. Its body shape and 
musculature appear to have been designed for that function, 
rather than a principally aquatic life (Figure 58). 
70 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY 
Ichnogenera and High-level Taxa 
Nomenclature to be applied to the "work" of animals, 
including such examples of life activity as bioturbation, 
borings into hard substrate, and coprolites, have constituted a 
serious issue for the International Commission on Zoological 
Nomenclature. The philosophical approach as to how to treat 
names based on such work has changed during several editions 
of the International Code of Zoological Nomenclature. These 
changes are aptly summarized by Bromley (1990:143-145). 
Currently (ICZN, 1985), no valid binomial can be based on the 
work of an extant animal, but the validity of ichnotaxa in the 
fossil record is recognized. There is no doubt that Climactich?
nites Logan and C. wilsoni Logan are names in good standing 
within zoological nomenclature. 
Still further, the Code (ICZN, 1985:51) notes: "(iii) a name 
established for an ichnotaxon does not compete in priority with 
one established for an animal, even for one that may have 
formed the ichnotaxon." One consequence of this wording may 
be to treat ichnotaxa as entities entirely distinct from any 
zoological considerations. Once it is established, for example, 
that Rusophycus is the name for the resting place of a trilobite, 
there may be little incentive in determining whether more than 
one kind of trilobite formed Rusophycus. For ichnofossils with 
fewer features than that one, such as the well known Skolithos, 
it is possible to examine the works of Recent tube-dwelling 
animals and determine that several different unrelated forms are 
capable of producing a tube like that of the fossil genus named 
Skolithos. Bromley (1990:137-142) again has most ably 
summarized the problems and pitfalls of attempting to correlate 
a particular trace fossil with a particular fossil organism. 
In the face of such obstacles, one is strongly tempted to 
forego any serious biological consideration of ichnotaxa, but 
we are troubled that this attitude may be retrogressive. 
Biological nomenclature is concerned with organisms, not 
sedimentary structures. Where sufficient detail is provided by a 
trace fossil to allow more detailed speculation regarding the 
organism which formed it, we judge that this line of inquiry 
should be vigorously pursued. Accordingly, once we had 
described the features of the trail of Climactichnites, we next 
attempted to reconstruct the organism which could have 
produced this particular structure. 
To state this matter more formally, we consider the name 
Climactichnites to apply to a fossil animal that so far is known 
only from its trail, not as the scientific name for a trail with 
certain characteristic features of morphology. In doing so, we 
recognize full well that such an approach is less readily applied 
to other ichnotaxa which have fewer features or less distinctive 
morphology, and that Bromley (1990) is correct in cautioning 
against too much biologic interpretation of traces. However, to 
treat Climactichnites purely as a trail and not as indication of an 
organism would seem to defeat the purpose of paleontology, 
the study of ancient life. Fortunately, our problem is somewhat 
simpler than with other collective group names, for no generic 
name of a body fossil has ever been linked to the trail of 
Climactichnites. Even the general group of animals which have 
been suggested in the literature as possible trail formers are, in 
our view, inappropriate. Climactichnites may be the exception 
which tries the rule, for if one cannot speculate about the 
organism that formed such a remarkable trail, one cannot 
properly speculate about the biological origin of almost any 
other trace fossil. 
Hantzschal (1962, 1975) discusses ichnogenera in alphabeti?
cal order. This has considerable merit for finding a name, but 
once again conveys a subliminal message that one is dealing 
with "things" rather than organisms. The Code does indicate 
that family-group names based on ichnogeneric names are 
valid, implying that even though ichnotaxa are in a sense 
artificial assemblages, a zoological classification is a goal for 
which to aim. 
Discussion 
The trail of Climactichnites is like that of no other trace 
fossil. We do not mean by this statement that it is simply a 
different genus; rather, its morphology is so strikingly different 
that it is not liable to confusion with any other traces of fossils 
known to us. Were one to apply a hierarchical classification to 
trace fossils, the form would be unique in its own high level 
taxon. As a direct conclusion, we judge that in its morphology 
Climactichnites was like no other animal. Based on our 
interpretation of its locomotion and feeding, we suggest that no 
skeletal material was present. Any slight similarities to 
present-day organisms are at best analogies, and, in our 
interpretation, indicate no relationship. We know of no other 
forms in the Precambrian or Paleozoic that in any way would be 
similar to it. 
Preservation of soft-bodied organisms is now generally 
accepted as a possibility in the fossil record, although deposits 
yielding such atypical fossils are still exceedingly rare in the 
Phanerozoic. In contrast, this is the norm for preservation in the 
Vendian. Based on what is known of the occurrence of such 
forms in the Paleozoic and what has been interpreted as the 
environment of deposition of the rocks yielding Climactich?
nites, the prospect of directly obtaining any part of the animal 
itself appears to be extremely remote. 
The mode of life suggested, that is brushing away the 
sediment surface to collect tiny organisms living interstitially 
in the upper layers of sand, seems to have no parallel in the 
modem fauna. In retrospect, this should come as no great 
surprise for, just as the vast carbonate-depositing epicontinental 
seas of the Paleozoic have no close present-day analog, the 
huge sand flats of the Late Cambrian in eastern North America 
differed from our modem high energy beaches. Apparently, by 
its nature, Climactichnites left only a trace and no body fossil 
for us to study. Although our interpretation of the animal 
contains many inferences, in our view, these fit all available 
data, yet do not consist of unbridled speculation. 
NUMBER 74 71 
This now brings us to the crux of a dilemma concerned with 
the issue of high-level taxa in classification. During the past 
generation there has been a dramatic change in the approach of 
many paleontologists from a more biostratigraphie interest to a 
more paleobiologic one. Included in this change has been the 
recognition that the early record of fossils at the taxonomic 
levels of order, class, and phylum might be dramatically 
different from that of the Recent biota. Whereas in the past, the 
erection of orders and classes of organisms having no 
present-day representatives was rare, now such categories are 
relatively common in the paleontologie literature. Two decades 
ago, proposal of an extinct phylum was a daring and somewhat 
unpopular step (Yochelson, 1977); today the pendulum has 
swung so far that there is concern in some quarters that certain 
unique fossil forms in such carefully documented faunas as the 
Middle Cambrian Burgess Shale have not been accorded their 
own phyla. 
A contrary view of this development is given by those who 
are concerned with what have been called "junk" phyla. This 
implies taxa which can only be recognized in exceptional 
preservation and are limited in both time and space. We reject 
this interpretation, for taxa at all levels are based on similarities 
and differences with other taxa. Neither abundance of the 
organism classified or its distribution in time are pertinent to 
taxonomic rank. If stratigraphic range were a serious considera?
tion of taxonomy, the "junk phylum" logic would dictate that a 
number of generally accepted Recent phyla, which have no 
fossil record, should be downgraded in rank. 
Another facet of this issue is the question of the origin of 
high-level taxa at the Precambrian-Cambrian boundary. For 
some investigators, development of new phyla at that time was 
an "explosion." In opposition to that is the presence of at least 
one major phylum?Bryozoa?appearing in significantly 
younger beds. If the Agmata (Yochelson, 1977) and the 
Conulariida (Feldmann and Babcock, 1986) are accepted as 
phyla, the force of the Cambrian explosion is weakened. 
The increase in the number of kinds of fossils with hard parts 
at the base of the Phanerozoic is true enough, but we judge the 
concept of "explosive evolution" to be more apparent than real. 
We hold that regardless of the time when it occurs, if an 
organism develops the means to exploit a major new 
environment, the result may be a form which fits no previously 
recognized taxonomic category, even at the highest systematic 
level. Because of the rapid filling of the most common 
ecological niches, the development of high-level taxa in 
post-Early Cambrian time was more difficult, but obviously not 
impossible. In a sense, we see Climactichnites as yet another 
attempt at a novel body plan in the post-Early Cambrian 
interval. 
Having written all this, we do not propose any formal 
high-level taxonomic assignment for Climactichnites at this 
time! It is unconventional to construct any animal from its 
work. It is even more unconventional to use the indication of 
the work of an animal, an ichnogenus if you will, as the basis 
for a high-level taxon. There are limits as to how far one can 
defy convention and still be accepted by ones colleagues. 
Classification differs from any other sciences in that it is an 
additive process, not episodically revised by new paradigms. 
Each new paper in systematics adds a modicum of data to our 
understanding of the interrelationships of organisms. Fortu?
nately, the term incertae sedis is available to the systematist, 
and, like the term taxon, does not imply any particular level of 
classification (see Yochelson, 1991). Although it may have 
been inadvertent on his part, Hantzschel (1975) took a dramatic 
step forward when he suggested that Climactichnites was the 
trail made by an unknown organism, rather than that of a 
mollusk, arthropod, or worm, and by implication classified the 
genus incertae sedis. 
In the final analysis, the position of taxa within a hierarchy 
of classification is subjective, for it depends entirely on 
subsequent acceptance or rejection by other interested systema-
tists. We are satisfied in our own minds that Climactichnites 
constitutes a form deserving of phylum-level rank, which for a 
brief time exploited the vast tidal sand flats of the Late 
Cambrian, becoming extinct when conditions changed only 
slightly. We have deliberately used the term incertae sedis in 
higher level classification of this fossil for two reasons. First, 
such usage dramatizes its distinctiveness, and, second, this 
avoids for the moment the issue of an ichnogenus as the basis 
for a phylum. If our interpretation of just how novel is 
Climactichnites is accepted by our scientific peers, and if the 
conventions are changed, a phylum name can be proposed later. 
For now, Climactichnites may speak for itself. 
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