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Lucas, S.G., et al. eds., 2013, Carboniferous-Permian Transition in Central New Mexico. New Mexico Museum of Natural History and Science, Bulletin 59.
FLORA OF THE LOWER PERMIAN ABO FORMATION REDBEDS,
WESTERN EQUATORIAL PANGEA, NEW MEXICO
WILLIAM A. DIMICHELE1, DAN S. CHANEY1, SPENCER G. LUCAS2, HANS KERP3 AND SEBASTIAN VOIGT4
1 Department of Paleobiology, NMNH Smithsonian Institution, Washington, DC 20560, USA;
2 New Mexico Museum of Natural History and Science, 1801 Mountain Rd. NW, Albuquerque, NM 87104, USA;
3 Forschungsstelle für Paläobotanik, Westfälische Wilhelms-Universität Münster, Schlossplatz 9, 48143 Münster, Germany;
4 Urweltmuseum GEOSKOP, Burg Lichtenberg (Pfalz), Burgstraße 19, D-66871 Thallichtenberg, Germany
Abstract—The Lower Permian, Cisuralian age Abo Formation and its equivalents of New Mexico contain a low
diversity flora dominated by several species of walchian conifers and the peltasperm Supaia thinnfeldioides. A
variety of much less common taxa includes the coniferophytes Cordaites and Dicranophyllum, the peltasperms
Supaia anomala, Brongniartites/Glenopteris, Autunia, Rhachiphyllum, and Gigantopteridium, the possible cycads
Taeniopteris, cf. Russelites/Yuania, and cf. Plagiozamites. A single site is dominated by Glossopteris/Lesleya-
shaped foliage. A few specimens of rare, more typically wetland taxa, are present, particularly the pteridosperm
Neuropteris, the sphenopsids Sphenophyllum and calamitalean stems, and the marattialean tree fern Pecopteris.
Total species diversity is about 27, which is remarkably low given that plants were identified at 172 red beds
sample sites covering a minimum area of about 83,000 km2, from the Robledo Mountains and Fort Bliss in
southern New Mexico, to the Zuni Mountains and Jemez Mountains in the north. This raises the question of
taphonomic bias; conifers and supaioids had unusually stiff, resistant construction, which may have differentially
favored their survival in depositional systems. A number of factors weigh against an interpretation of special
biases, unique to these deposits. Abo red beds are sedimentologically heterogeneous, not consisting of one particu-
lar kind of environment for plant preservation. Yet, conifers and supaioids remain the most commonly represented
plants throughout, both in still-water dense-debris accumulations and in active flow deposits where remains are
generally isolated. Additionally, conifers and supaioids, although occurring together in many deposits, do not co-
dominate sites, and mostly occur in isolation from one another, suggesting very different ecological distributions.
Rare taxa, in contrast, mostly occur as singletons, or in assemblages that they dominate, less commonly mixed with
conifers and supaioids, suggesting patchy distributions on the landscape, not preservational biases as the cause of
their rarity and the generally low diversity.
INTRODUCTION
The change in floral composition from the Pennsylvanian to the
Permian is well documented in the Euramerican parts of central and
west-central Pangea, present day western North America through Eu-
rope. Here, assemblages of xeromorphic plants replaced wetland plants
as the most commonly encountered vegetation of equatorial lowland
basins. This change was driven principally by long-term, directional, if
oscillatory, changes in the seasonality of rainfall and perhaps mean an-
nual rainfall, across most of central and western Pangea, beginning in the
Middle Pennsylvanian (Moscovian) and continuing through the Late
Permian.
In the westernmost parts of Pangea, represented today by west-
ern North America, the rise in the frequency of occurrence of seasonally
dry vegetation in basinal lowlands took place much sooner than in the
peat-forming coal basins of the central portions of the supercontinent,
beginning in the west at least by the Middle Pennsylvanian and perhaps
even earlier in some regions (Tidwell and Ash, 2003). By the Middle
Pennsylvanian, such plants as conifers, the pteridosperm
Sphenopteridium, the cycadophytes Charliea and Taeniopteris,
cordaitaleans and other plants that typify seasonally dry substrates had
become widespread and abundant in the western reaches of Pangea and
were penetrating into the central regions, especially during the drier
portions of glacial-interglacial cycles (Plotnick et al., 2009; Falcon-Lang
and DiMichele, 2010; Falcon-Lang et al., 2011). By the Pennsylvanian-
Permian transition, this changeover was essentially complete in most of
the western reaches of the equatorial zone, resulting in widespread devel-
opment of a complex, seed-plant dominated vegetation that was highly
habitat differentiated, given its regional and sometimes local variability
(Tidwell and Ash, 2004; DiMichele and Chaney, 2005). And, by the
Early Permian, a widespread, conifer and peltaspermous pteridosperm
vegetation dominated large portions of seasonally dry areas of the central
and western Pangean continent (Kerp and Fichter, 1985; Kerp, 1996;
Galtier and Broutin, 2008; Tabor et al., 2013). Existing side-by-side with
this seasonally dry substrate flora was a now-depauperate wetland veg-
etation, probably confined to riverine corridors, stream floodplains and
lakesides, where persistent soil moisture was present (DiMichele et al.,
2006).
The Early Permian Abo Formation red beds, and their equivalents,
in central New Mexico formed as a widespread inland to coastal fluvial
complex. The formation is composed of fine-grained sandstone- and
siltstone-filled channels alternating with well developed vertic, and often
calcic paleosols (Mack et al., 1991, 2010; Mack, 2003, 2007), indicating
a seasonal climate, with long or intensely dry periods. It has long been
known as the source of a low diversity, conifer-dominated paleoflora
(Hunt, 1983; Lucas et al., 1999), one that occurs in close association with
vertebrate and invertebrate trackways (Lucas and Heckert, 1995) and
occasional vertebrate skeletal remains (Lucas et al., 1999, 2009). The
flora is preserved mainly as impressions, which has made it of limited
interest for studies of plant morphology, there being no structural pres-
ervation, little or no cuticle, and with finer details of surface morphology
often obscured. Nonetheless, there are reports of well preserved plants
at some locations (e.g., Hunt, 1983; DiMichele et al., 2007), and these
floras can, in many instances, be linked to depositional environments,
permitting understanding of much of their taphonomy. Furthermore, the
very low diversity of the Abo Formation red beds flora, especially the
266
conspicuous and overwhelming dominance of conifers and supaioid plants,
is of interest. This low diversity is spotlighted further by the presence of
higher diversity gray, generally siltstone-to-sandstone facies in the lower
Abo Formation throughout much of its outcrop area. These gray depos-
its, inter-tongued with or laterally equivalent to the Abo red beds, not
only contain a higher diversity flora than that of the red beds, but that
flora differs in significant ways from that of the red beds. Consequently,
the high dominance and low diversity of the Abo red beds over a spatially
large area, is noteworthy and perplexing.
GEOLOGY OF THE ABO FORMATION AND EQUIVALENTS
The Abo Formation, and its correlatives in New Mexico, crop out
in a north-south band through the center of New Mexico, primarily along
the margins of the Rio Grand rift system, from near the southern borders
of the state on the Ft. Bliss Military Reservation, near El Paso, Texas and
the Robledo Mountains, near Las Cruces, to northern New Mexico, in
the Zuni Mountains near Gallup and the southern Jemez Mountains
west of Santa Fe (Fig. 1). The type area (Fig. 1 – labeled “Abo Pass”) is
within Abo Pass at the southern end of the Manzano Mountains in
western Torrance County (Lucas et al., 2005, 2013). In the vast majority
of the Abo outcrop area the formation is entirely of terrestrial (fluvial)
origin (Lucas et al., 2005, 2012). In southern New Mexico the terrestrial
Robledo Mountains Formation, an Abo lithological equivalent, interfingers
with marine units of the Hueco Group in its lower parts (Fig. 2) (Krainer
and Lucas, 1995; Krainer et al., 2009; Mack, 2007; Voigt et al., 2013).
The intertonguing of the siliciclastic Abo red-bed lithosome and the car-
bonate-dominated Hueco Group lithosome extends across southern New
Mexico, in Doña Ana, southern Sierra and Otero counties, and is seen on
outcrop in the Robledo, Doña Ana, San Andres, southern Caballo, Jarilla
and Sacramento Mountains (e.g., Kottlowski et al., 1956; Bachman and
Hayes, 1958; Pray, 1961; Lucas et al., 1995, 2002, 2012).
In a general sense, the Abo Formation (including its terrestrial
equivalents, Fig. 2) can be divided into a lower third dominated by mud-
stone and channel-form sandstone, the Scholle Member, and a siltstone-
sandstone-dominated upper two thirds, the Cañon de Espinoso Mem-
ber, marking a generally fining upward profile. In the Scholle Member,
sandstone channels, many with conglomeratic basal lags and erosional
basal contacts, are incised into thick, clay-rich paleosols of vertic charac-
ter, often with carbonate nodules. Channel sands may be flanked by thin,
tabular, flat-bottomed sheet fine sands and siltstones. The Cañon de
Espinoso Member consists dominantly of fine-grained sheet sandstones
and siltstones separated by mudstones, generally with pedogenic over-
printing of vertic and sometimes calcic character.
In many of the sheet sandstones and siltstones from throughout
the formation, the upper parts of beds, sometimes just a few centimeters
and occasionally significantly more, consist of an upward-fining sequence
of siltstone/sandstone and siltstone/claystone interbeds. The finer grained
sediments frequently show evidence of flow under partially exposed
conditions (rills and small runoff features), or complete exposure, such
as mud cracks, often of multiple generations on a single surface, and
raindrop imprints. On some of the finer grained surfaces, footprints and
trackways of vertebrates and invertebrates are common (Lucas and
Heckert, 1995). These finer-grained layers also often include plant fos-
sils, from isolated specimens to abundant masses of foliage and branches
(DiMichele et al., 2007). Plant fossils also occur, however, in the sand-
stones themselves, often crossing bedding planes, suggesting transport
and rapid deposition. As with the finer grained layers, plant fossils in
sandstones and siltstones may occur in isolation or as part of more
concentrated accumulations.
In many parts of the Abo outcrop area, exposures do not permit
exact assessment of position within the formation. This results from the
influence of cover, faulting, and erosion, which may obscure the base or
top, and, in the case of faulting and erosion, often remove parts of the
formation from the local outcrop.
MATERIALS AND METHODS
Abo Formation exposures were examined throughout the outcrop
area (Fig. 1). The objective was to find and identify plant fossils, their
environment of deposition, and, as far as possible, their position within
the Abo Formation (lower, middle, upper). Due to the often incomplete
nature of Abo Formation exposure, correlation from one exposure to
another was confined to a broad classification of upper and lower, some-
times middle. Basal exposures in the immediately overlying Yeso Group
also were examined in many places.
When plant fossils were found, their geographic position was
recorded. A geologic description was made, and the outcrop was photo-
graphed. As often as possible, plant-fossil occurrences were put into the
larger context of position within the local Abo section.
If it proved possible to collect specimens, a collection was made
from a plant-bearing site. Because of the nature of the rocks, it was not
always possible to remove specimens, particularly where the matrix was
massive and the fossils were not on a bedding surface that could be
removed with hand tools. In the many instances where the flora was
monotypic and the number of specimens that could be collected large,
only a voucher or two was removed to serve as a record of that locality.
As often as possible, specimens were photographed in the field, particu-
larly if they could not be removed. In some cases, plant fossils were
found in debris fans derived from weathering of several siltstone/sand-
stone beds, and thus could not be related with absolute certainty to a
particular layer; in these instances a “float” collection was made, and so
labeled.
Specimens referred to in this study are housed either in the paleo-
botanical collections of the National Museum of Natural History,
Smithsonian Institution, Washington, DC (USNM), or the paleontologi-
cal collections of the New Mexico Museum of Natural History and
Science, Albuquerque, NM (NMMNH).
FIGURE 1. Outcrop area of the Abo Formation and its equivalent units in
New Mexico. Sites from which fossil plants were collected are marked by
open circles (red beds) or black crosses (gray beds).
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RESULTS
Fossils were collected from 172 discrete red bed sites and cover
the full range of the Abo Formation, both geographically and
stratigraphically. Many areas, and some deposits, were collected more
heavily than others, there being more individual collections made; in
some instances these collections were replicates, collected from a dis-
crete and identifiable sedimentary unit. However, the great majority of
collections are isolated occurrences, most often from beds that either
could not be traced over any distance, or, more often, that had plant
fossils only at one or a few widely spaced points. Thus, we report the
data for the full set of collections instead of agglomerating them by site,
where possible.
Composition of the Flora
A comparison of the red beds and gray beds floras is summarized
in Table 1.
Only three species occur at more than 10% of the red beds sam-
pling sites: Walchia piniformis (49%), Otovicia hypnoides (difficult to
separate from Brachyphyllum?, 13%), and Supaia thinnfeldioides (25%)
(Table 1).
When looked at from the viewpoint of major evolutionary lin-
eages, only three of the lineages – conifers (82%), supaioid peltasperms
(28%), and callipterid peltasperms (12%, the most abundant of which
individually is the small form of Autunia conferta, 9%) – occur at more
than 10% of the collecting sites.
Diversity at any one collecting site averages about 2 species, with
a maximum of 7 species from any field site. Nine species were found at
one site that was collected heavily over a large area from multiple sites by
Adrian Hunt (1983) in his study of the Abo Formation flora in parts of
Socorro County.
FIGURE 2. Stratigraphic nomenclature and correlation of the Abo Formation and equivalent units from north-central New Mexico (left) to south-central
New Mexico (right). The Pennsylvanian-Permian boundary, at the time of writing of this paper, is at the Newwellian-Nealian contact.
TABLE 1. Percentage occurrences of taxa at sites examined in the Abo
Formation red facies and gray facies. **** = Taxa that occur commonly in
both red and gray facies. ^^ = Taxa that occur commonly in only one facies.
268
Total diversity consists of 28 discrete species, more or less, de-
pending on how the small filicalean ferns are subdivided, whether the
conifer morphotypes are reliable indicators of discrete species, and how
many species are tied up in the calamitalean stems, and so on. The total
red beds flora consists of the following: Walchia piniformis, Otovicia
hypnoides (+ Brachyphyllum?), Hermitia schneideri, Culmitzschia
americana, Culmitzschia speciosa, Dicranophyllum sp., Cordaites spp.,
Supaia thinnfeldiodes, Supaia anomala, Brongniartites sp., Autunia
conferta (small form), Autunia conferta (large form), Rhachiphyllum
lyratifolia, Rhachiphyllum schenkii, Gigantopteridium americanum,
Taeniopteris (3 distinct morphotypes), Charliea/Russelites/Tingia sp.,
Plagiozamites sp., cf. Glossopteris/Lesleya, Neuropteris sp., indetermi-
nate calamitalean stems, Sphenophyllum, Pecopteris sp., and small filicalean
ferns.
Only a limited number (30) of Abo Formation gray-bed sites have
been analyzed to date (Table 1), but these yield plants that differ greatly
from those of the red beds in their patterns of dominance and diversity,
although many species co-occur, suggesting a shared regional species
pool. Gray beds are mainly confined to the lower part of the Abo Forma-
tion or its equivalents, are largely represented by channel fills of rela-
tively coarse siltstones and sandstones, and may have been deposited
primarily in braided channel belts, with wet braid plains. Nineteen taxa
occur at =/> 10 % of the sample sites. None of these, individually, are
supaioids. Conifers as a group occur at 73% of sample sites; Walchia
piniformis (50%), Culmitzschia speciosa (23%), Otovicia hypnoides
(10%), Culmitzschia americana (identified in 1938 by Rudolf Florin as
Lebachia americana, according to collection notes; 10%) and
Ernestiodendron (3%). Cordaitalean foliage occurs at 40% of sampling
sites. Supaioids, collectively, occur at 10% of the sampling sites: Supaia
thinnfeldioides (7%) and cf. Brongniartites (7%). Seven types of
callipterids occur collectively at 37% of sampling sites, including Autunia
conferta, small (10%) and large (3%) forms, A. naumannii (3%)
Rhachiphyllum lyratifolia (10%), R. schenkii (20%), Lodevia sp. (13%),
and Dichophyllum flabellifera (3%). The lyginopterid pteridosperm
Sphenopteridium cf. manzanitanum (10%), not present in the red beds,
is present at 10% of gray beds sites. Possible cycadophytes include
Taeniopteris, which occurs at about 14% (combining two forms) of sites,
whereas it is present at no more than 2% of red beds localities, and
Plagiozamites, a single occurrence (3%). At gray beds sites, medullosan
pteridosperms also are common elements, including Odontopteris sp.
(20%), Mixoneura sp. (3%), Neurodontopteris auriculata (10%),
Neuropteris sp. (10%), Callipteridium (7%), Alethopteris sp. (10%), and
Pseudomariopteris (3%). In addition, the tree fern foliage Pecopteris is
present at 20% of sites examined, whereas it is present at only 2% of red
beds sites. Together with the pecopteroids, the most reliable indicator of
local wet landscape areas are the calamitaleans. This group is represented
by foliage forms Annularia sp. and Asterophyllites equisetiformis, each
present at 6% of collecting sites, and by calamitalean stems, which occur
at 33% of sites examined. The lycopsid Sigillaria brardii, almost cer-
tainly an indicator of swampy landscape conditions, is entirely absent
from the red bed samples, but occurs at 13% of the gray facies sample
sites.
There also are several sites in the lower Abo Formation that can be
described as dolomitic limestones containing plant fossils. Only one of
these sites was examined in detail, “Site Flood” from the Abo equivalent,
Community Pit Formation (see Fig. 2), of the Robledo Mountains (Lucas
et al., 2013). This flora is entirely different from any other found in the
Abo Formation or its equivalents. The most common elements in the
flora are a conifer that is likely a previously undescribed voltzialean
(Cindy Looy, personal communication, 2012) and the callipterid
Dichophyllum flabellifera. Also present, but uncommon, are cordaitalean
leaves, and Annularia spicata calamitalean foliage.
Illustration of the Flora
Representatives of the flora of the Abo red beds are illustrated in
Figures 3-18, approximately in the order of importance of the taxa in
terms of their relative frequency of occurrence.
Figures 3 through 5 are conifers. The taxonomy of conifers is
among the most difficult among late Paleozoic fossil plants, rivaling that
of the marattialean ferns. Thus, the names below are effectively place
holders. Conflicts in taxonomic practice (Visscher et al., 1986; Mapes
and Rothwell, 1991) have, in some instances, created communication
difficulties with regard to these plants. Because we are dealing nearly
entirely with vegetative remains, lacking cuticle and, in many cases,
detailed surface features of any kind, we have adopted a modified system
based largely on that of Visscher et al. (1986) and Broutin and Kerp
(1994). Hermitia schneideri is not illustrated; originally described as
Walchia schneideri, it was transferred to Hermitia by Visscher et al.
(1986).
Figure 3. Walchia piniformis
Conifer specimens identified as W. piniformis are the most com-
monly encountered plant fossils in the Abo Formation. These are for the
most part fragmentary, but entire branches up to 80 cm in length, and
large branch fragments, such as those illustrated, are common. These
specimens have small, narrow, elongate leaves that curve inwardly acro-
petally.
Figure 4. Otovicia hypnoides/cf. Brachyphyllum
A large number of conifer specimens have small leaves of triangu-
lar shape that are adpressed to various degrees to the axis. In some
specimens, these leaves are so closely adpressed that they may be diffi-
cult to distinguish in mold-cast type preservation. The specimens illus-
trated in Figure 4.1-4.3 illustrate this condition. Such specimens are
similar to those that Mamay (1967) designated Brachyphyllum? densum,
from the Lower Permian of north-central Texas, beds that may correlate
to some part of the uppermost Abo Formation. In other instances, such
as the specimen illustrated in Figure 4.4, the leaves are less closely
pressed against the supporting branch, though they are still generally
triangular in shape. This is the more common morphology of the two,
which we have designated Otovicia hypnoides. Figure 4.5 is a specimen
that probably belongs to O. hypnoides, but illustrates some of the diffi-
culties encountered when identifying these fragmentary specimens.
Originally described as Walchia hypnoides, this species was re-
named and transferred to Otovicia on the basis of reproductive morphol-
ogy. It differs from Walchia in having two fertile scales per dwarf-shoot;
sterile and fertile scales are morphologically very similar, unlike the
pattern in Walchia, where they differ in form (Kerp et al., 1990).
Figure 5. Culmitzschia americana and Culmitzschia cf. speciosa
Housed in the USNM collections are specimens from the Penn-
sylvanian-Permian boundary in central New Mexico identified in 1938
by Rudolf Florin as Lebachia americana; this species was later trans-
ferred to Culmitzschia (Clement-Westerhof, 1984). It is not certain if
Florin examined these specimens in Washington, DC, or if they had been
sent to him for assessment. Specimens of the type illustrated in Figure
5.1 and 5.2 were designated by Florin (1939) as Lebachia americana. We
use the name C. americana here as a designation for this morphology,
characterized by conifer stems bearing relatively small, straight, needle-
like leaves. These leaves rarely show any acropetal inward curvature
and, in fact, may arc slightly away from the stem instead of toward it, as
illustrated in Figure 5.1. The specimen illustrated in Figure 5.2 also
demonstrates preservation in a thin mud layer, or “drape” that also
partially covers the branch fragment.
Figure 5.3 illustrates the most robust type of conifer foliage found
in the Abo. Leaves are relatively large and curve inward at their tips
acropetally. We have designated such specimens Culmitzschia cf. speciosa.
Neither of these forms are common in the Abo Formation red
beds.
269
FIGURE 3. Walchia piniformis. 3.1, USNM specimen 558251; USNM locality 43557. 3.2, USNM specimen 539454; USGS locality 8979.
Figure 6. Supaia thinnfeldioides
Next to the conifers, the supaioid peltasperms, particularly S.
thinnfeldioides, are among the most commonly encountered plants in the
Abo Formation red beds. Supaia thinnfeldioides is characterized by small,
forked fronds (Fig. 6.1), in which the venation is often obscure, perhaps
due to the thickness or leathery nature of the leaf in life (e.g., Figs. 6.1 and
6.3). In some instances, however, the venation is visible and is character-
istically arcing at a high angle (Fig. 6.2). Many species of Supaia were
described by White (1929) from deposits of the Hermit Shale, in the
Grand Canyon of Arizona. Many of these may be varieties of a single
species; we have been very cautious in making determinations based on
White’s original work and have treated the wide range of morphological
variation found in Abo specimens as S. thinnfeldioides, which is the most
common and abundant of White’s species in the Hermit Shale collec-
tions.
Figures 7 and 8. Supaia anomala
In his 1929 Hermit Shale monograph, White described specimens
as Supaia anomala that were quite different in overall morphology from
the many other species of Supaia he described. As discussed in DiMichele
et al. (2007), S. anomala appears to be a chimera of at least two forms,
one of which, the most diagnostic for this species, likely falls outside the
270
FIGURE 4. cf. Brachyphyllum sp./Otovicia hypnoides. 4.1, USNM specimen 558269; USGS locality 8981. 4.2, USNM specimen 558270; USNM locality
43441. 4.3, Field Photograph; USNM locality 43559. 4.4, NMMNHS P-42802; NMMNHS Cañoncito de la Uva locality. 4.5, Field Photograph; USNM
locality 43560.
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FIGURE 5. Culmitzschia americana. 5.1, USNM specimen 558272; USGS locality 8993. 5.2, USNM specimen 558299; USNM locality 42340; Culmitzschia
cf. speciosa. 5.3, USNM specimen 558271; USNM locality 43429.
generic concept of Supaia. This leaf-type consists of a ribbon-like lamina
that flanks the petiole and all orders of branching of the rachis. The leaf
is forked at the top of the petiole (the length of which we have not been
able to determine) into two mirror-image segments (Figs. 7.1, 8). Divi-
sions of each of the resulting primary rachises produce a
pseudomonopodial arrangement with lateral, ribbon-like secondary ra-
chises/pinnae departing at high angles. In some cases, these rachises/
pinnae may again fork (Fig. 7.2). As seen in Figures 7.2 and 8, venation of
the laminae is arching and slightly S-shaped.
Figure 9. Autunia conferta
Callipterids are the third most common major group of plants in
the Abo red beds, and the majority of these occurrences are of Autunia
conferta. This iconic callipterid, formerly treated as an index species for
the base of the Permian, is widespread across Europe and North America
in rocks of latest Pennsylvanian and early Permian age. Most of the
specimens in the Abo have been found in isolation and in the uppermost
portions of the unit. Two morphologies occur that can be attributed to
this species. Kerp (1988) described and illustrated a large range of varia-
tion in this species; large population sizes suggest overlap between the
larger and smaller forms but, nonetheless, these are clear size centroids
that are more or less common in different regions of Pangea. For example,
in Europe, the Dunkard Group of the Appalachian Basin, and the Abo
Formation of New Mexico, the small form of this species is by far the
272
FIGURE 6. Supaia thinnfeldioides. 6.1, USNM specimen 558273; USGS locality 8979. 6.2, USNM specimen 558274; USNM locality 42110. 6.3, USNM
specimen 558252; USGS locality 8977.
most commonly encountered. However, in the north-central Texas Penn-
sylvanian-Permian sequence, the large form is almost exclusively found.
The specimen illustrated in Figures 9.1 and 9.2 is very small but could be
part of a frond of a young plant. Differences in size in A. conferta
specimens are mostly related to their habitat; those growing in relatively
humid conditions appear to have had larger, sometimes pinnatifid pin-
nules, whereas those growing in more water-stressed environments ap-
pear to have had smaller pinnules (Kerp, 1988).
Figures 9.1-9.3 illustrate fragmentary specimens of the small form
of A. conferta. The white arrow in Figure 9.2 points to rachial pinnules
characteristic of A. conferta. Note also the prominent midveins, indica-
tive of vaulting of the lateral pinnule laminae, regularly triangular pinnule
shape, bluntly pointed pinnule apices, and elongate terminal pinnules.
Figure 9.4 illustrates the larger form of what is probably A. conferta,
though this is still a small specimen, from the terminal portion of a lateral
pinna. It differs somewhat from the smaller forms in the slightly acro-
petal constriction of the pinnule lamina, the more elongate nature of the
pinnules, and the angular midvein that appears to cross the pinnule
lamina from its point of insertion on the basipetal side to its apical
position somewhat to the acropetal side of the lamina. The midveins are
prominent, the lamina vaulted, the insertion angular, and the laminar
veins steep and relatively straight.
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FIGURE 7. Supaia anomala. 7.1, USNM specimen 558275; USGS locality 8980. 7.2, USNM specimen 558276; USNM locality 42265.
Figure 10. Brongniartites sp. and Gigantopteridium americanum
Both of these plants are possibly peltasperms, based on their
foliar morphology.
Brongniartites (probably an invalid name – see Naugolnykh, 1999)
is part of a complex of likely related “supaioid” plants that can present
identification challenges when preserved as fragmentary material (see
DiMichele et al., 2005). The specimen illustrated in Figure 10.1, al-
though incomplete, shows the acropetally expanding pinnule size and
what appears to be an unforked primary frond axis, typical of what we
have classified as Brongniartites sp. Another possible identification of
leaves of this type is Glenopteris, another probable peltasperm with an
unforked frond, found in the southwestern United States (Krings et al.,
2005).
The Gigantopteridium americanum specimen (Fig. 10.2) shows
the typical gross architecture of an American gigantopterid. The strong
grooves that run slightly angularly through the lamina to the margins
mark the position of the main lateral, or secondary veins. The lateral
veins can be seen in some parts of the lamina, despite the generally poor
preservation of the specimen (Fig. 10.2, white arrows) and are of a
ragged, fasciculate form, typical of Gigantopteridium. Suture veins are
very difficult to recognize because of the preservation in sandstone.
Both of these taxa are very rarely encountered in the Abo red beds.
The gigantopterid was the dominant element at the site where it was
collected.
Figure 11. Comia craddockii
Comia is another suspected peltasperm that appears as part of a
major radiation of this lineage during the later Pennsylvanian and Early
Permian (DiMichele et al., 2005). The plant was not identified posi-
tively in the red Abo Formation facies. At a single location in the Doña
Ana Mountains of southern New Mexico, however, a few specimens of
this plant occurred in buff siltstones of the Robledo Mountains Forma-
tion (see Fig. 2). The only other reports of its occurrence are from north-
central Texas, in the late Wolfcampian or early Leonardian (Sakmarian-
Artinskian) (Mamay et al., 2009). The leaf of this plant shows a pinnate
architecture, visible in Fig. 11.1. Higher magnification images of that
274
FIGURE 8. Supaia anomala. USNM specimen 558277; USNM locality 42265.
275
FIGURE 9. Autunia conferta. 8.1, USNM specimen 543955; USNM locality 42251. 8.2, USNM specimen 543955; USNM locality 42251. 8.3, USNM
specimen 558268; USNM locality 43447. 8.4, USNM specimen 558278; USNM locality 42264.
276
FIGURE 10. cf. Brongniartites sp./Glenopteris sp. 10.1, USNM specimen 558280; USGS locality 8980. Gigantopteridium sp. 10.2, USNM specimen
558281; USNM locality 43562.
same specimen (Fig. 11.2) and another (Fig. 11.3) demonstrate the char-
acteristic fasciculate organization of the 4th order veins.
Figure 12. Taeniopteris spp.
The taxonomy of Taeniopteris below the generic level is suspect;
our own attempts to sort out species morphometrically, based on large
collections, and using features of venation and leaf shape, have failed to
define groups that can be repeatedly recognized in the field or in collec-
tions. Overlap among various measureable characters is high and incon-
sistent from specimen to specimen. There are a number of described
species in the genus (see discussion in Wagner and Martinez Garcia,
1982), and attempts have been made to bring order to these (Remy and
Remy, 1975). The genus includes both ferns and seed plants, although
the larger forms all appear to be of seed-plant affinities.
There are several kinds of Taeniopteris in the Abo Formation red
beds, judged by the gross morphology of the leaves. None are common.
Figure 12.1 is noteworthy because several Taeniopteris leaves appear to
be attached to a common axis in a regular helix and to be apetiolate; in our
experience, this is the only documented occurrence of such attachment in
American specimens. Figure 12.2 shows a typical leaf apex with strongly
developed, straight lateral veins. The significance of this trait, however,
is uncertain, given that angle of veins can vary strongly among specimens
277
FIGURE 11. Comia craddockii. 11.1, USNM specimen 558282; USNM locality 42271. 11.2, USNM specimen 558282; USNM locality 42271. 11.3,
USNM specimen 558283; USNM locality 42271.
278
FIGURE 12. Taeniopteris spp. 12.1, USNM specimen 543956; USNM locality 42255. 12.2, USNM specimen 558284; USNM locality 43435. 12.3, USNM
specimen 558285; USNM locality 42255. 12.4, USNM specimen 558286; USNM locality 42255.
of Taeniopteris from the same fossil population (one, sedimentologically
constrained deposit at one collecting site), as can the number of vein
bifurcations. The specimens illustrated in Figures 12.3 and 12.4 are part
of the same assemblage as is the specimen illustrated in Figure 12.1. The
veins in these leaves are faint, but can be seen in Figure 12.3, where they
are slightly angular in their insertion and very straight. As with the leaves
in the specimen illustrated in Figure 12.1, they appear to be apetiolate
and to have a marked basal abscission zone (Fig. 12.4).
Figure 13. cf. Glossopteris/Lesleya
Undoubtedly, the most perplexing specimens found in the Abo
red beds are from a site or proximate sites in the Zuni Mountains in
northern New Mexico. The collections in the USNM were made in the
first half of the 20th century by the University of New Mexico, and later
by the U.S. Geological Survey from places we have not been able to
relocate exactly. They are preserved in red, fine-grained sandstone that
appears to have been deposited rapidly; some of the specimens have
279
FIGURE 13. cf. Glossopteris/Lesleya sp. 13.1, USNM specimen 559287; USNM locality 43680. 13.2, USNM specimen 558288; USNM locality 43680.
13.3, USNM specimen 588289; USNM locality 43680.
280
leaves still in attachment to stems, or branches, reflecting either burial of
branches broken off in storms, or burial of small plants in situ (Fig. 13.1).
In either instance, this further suggests that the plants were living in
environmental settings close to actively flowing streams. As can be seen
from Figures 13.1-13.3, the leaves are large, apetiolate, spatulate in shape
with entire margins, rounded apices, and a strong midvein that runs from
the base to the tip of the leaf. Lateral veins, though not well preserved,
can be seen in Figure 13.2; these appear to be arching, open-dichoto-
mous, and multi-forked. The specimens most closely resemble the early
and early Middle Pennsylvanian plant Lesleya (Leary, 1990) or some
forms of the Southern Hemisphere Permian plant Glossopteris. The
closest comparison is with Lesleya, an enigmatic plant that apparently
favored moisture-stressed habitats, possibly developed on limestone
soils. Like the Abo specimens, Lesleya leaves are obovate, apetiolate,
and have arching, open dichotomous venation. Although similar in shape
to Glossopteris, the Abo Formation leaves do not have the reticulate
venation that characterizes this genus. Species of Glossopteris were
dominant in many temperate-climate environments of Gondwana, where
the plant has been shown to be seasonally deciduous (e.g., Gould and
Delevoryas, 1977). More northerly occurrences also are known from the
Permian of Oman (Broutin et al., 1995; Berthelin et al., 2003, 2006) and
southeastern Turkey (Wagner, 1962; Archangelsky and Wagner, 1983);
both of these peri-Tethyan areas were positioned at higher latitudes
during the Permian, and in tropical climates. Both the Turkish and Oman
floras are a mixture, mainly of Cathaysian and Gondwanan taxa; in Oman
some Euramerican taxa also have been recorded. There also are reports of
leaves of Glossopteris-type morphology from the Jurassic (Delevoryas,
1969), so, convergence must be considered a real possibility, in the ab-
sence of reproductive organs.
Figure 14. Dicranophyllum sp. and Plagiozamites sp.
These two genera occur very rarely in the Abo red beds, and are
elements typical of seasonally dry assemblages.
Dicranophyllum is a coniferophyte (Rothwell and Mapes, 2001).
Found mainly as vegetative remains, with foliage often attached to stems,
the plants are characterized by narrow leaves that undergo one or more
bifurcations (Barthel, 1977; Wagner, 2005). There is only a single vein
per leaf, which appears to be the case in the specimens found in Abo
sandstones (Fig. 14.1). A relatively large number of species have been
described, including D. readii from the Missourian-age Kinney Brick
Quarry flora in the Manzanita Mountains of Bernalillo County, New
Mexico (Mamay, 1981). Wagner (2005) notes, however, that due the
rarity of this genus, and its long stratigraphic range (known from the Late
Mississippian through the Early Permian), there probably were far fewer
species than actually described. Barthel and Noll (1999) have recon-
structed the plant as a small to medium sized shrub with a “bottle brush”
habit – a mainly straight stem surrounded by a dense covering of leaves.
The Abo plant is broadly similar to Dicranophyllum gallicum, which is
the most commonly found form in Upper Pennsylvanian and Lower
Permian deposits.
Plagiozamites is another long ranging, widespread genus, occur-
ring through much of the later Pennsylvanian and into the Permian,
across the Pangean equatorial region. Its affinities are most likely with
the Noeggerathiales, an enigmatic group of heterosporous lower vascu-
lar plants (Wang et al., 2009). Only a single specimen is present in the
Abo Formation exposures and collections we examined (Fig. 14.2).
Plagiozamites leaves were compound. The individual pinnules are flat,
elongate, and have a broad attachment to the pinna rachis. As visible in
the specimen illustrated in Figure 14.2, the veins run parallel to the long
axis of the pinnule and terminate at the bluntly rounded, slightly asym-
metrical pinnule apex. In well preserved specimens, the curved, apical
region of the pinnule is slightly crenulate, with veins ending in the crenu-
lations. This specimen is similar to Plagiozamites planchardii, which,
though rare, is widely reported in North America, including early Late
Pennsylvanian (Missourian) occurrences in the Appalachian Basin
(Bassler, 1916) and New Mexico (Mamay, 1990).
Figures 15, 16, 17. Wetland elements in the Abo red-beds facies.
A small number of taxa typically found in wetland floral associa-
tions occur in the Abo red beds. All are rare, but occurrences are wide-
spread.
The most common of these wetland elements are the pecopteroid
ferns, two specimens of which are illustrated in Figure 15. The
pecopteroids are a very widespread plant group that began significant
increases in dominance and diversity during the Middle Pennsylvanian
and became very diverse and abundant in wetland floras during the later
Pennsylvanian (Cleal et al., 2012). In the Permian, particularly in drier
landscapes, the pecopteroids persisted, but became both much rarer and
less diverse. They probably grew in streamsides or local swampy areas
where substrate moisture remained high, even if overall climate was
strongly seasonal (DiMichele et al., 2006).
Also found widely, but generally not identifiable to species, were
stem remains (Fig. 16.1) and possible foliar remains (Fig. 16.2) of the
bushy scrambling/climbing sphenopsid Sphenophyllum. In all instances
where such material has been found, it appears to have been buried
rapidly in fine-grained sandstone, probably reflecting growth in stream
side settings where occasional floods entombed local vegetation. The
foliage illustrated in Figure 16.2 is perhaps assignable to the calamitaleans,
as a species of Annularia; these specimens bear a vague resemblance to A.
spicata in the fusiform shape of their leaves, though they are oversized
for that particular species. In addition, it is possible that the leaves have
multiple veins, which would rule out an assignment to Annularia and
suggest, rather, affinities with Sphenophyllum, though no species assign-
ment is possible.
Figure 16.3 illustrates one of only two specimens of Sphenopteris,
the foliage of filicalean ferns, found in this study. The poor preservation
of the specimen is due, in part, to a cover of fine clay, which has obscured
the surfaces of the pinnules. Small, ground cover, climbing or epiphytic
ferns are essentially absent from the Abo red-beds flora. Rare occur-
rences suggest that they were present locally on the landscape, but the
near absence of these plants over such a large landscape area does not
appear to be reflective of a persistent taphonomic filtering effect.
Also vanishingly rare are medullosan pteridosperm remains, a
group generally rare in the Lower Permian. Figure 17 illustrates one of
the very rare occurrences of foliage possibly attributable to Neuropteris,
though no definitive species assignment is possible. Attribution to
Neuropteris is supported by the narrow insertion on the supporting
rachis, a distinct midvein that extends about 2/3 of the length of the
pinnule lamina, arched lateral veins and the slightly auriculate basipetal
margin of the pinnules.
Figure 18. Miscellaneous elements.
Figure 18 is a collection of miscellaneous elements identified in the
Abo red beds. Figure 18.1 is one of several specimens, found at a single
locality, that appear to be strobili borne at the end of an axis. The axis is
obscure, but appears to be small, closely adpressed, and of triangular
shape, similar to that we have attributed to Otovicia hypnoides or cf.
Brachyphyllum.
Small, bivalved or possibly trivalved (one valve may still be bur-
ied in the rock) sporangia are illustrated in Figure 18.2. Although uncom-
mon, these sporangia occur widely, in large numbers on bedding planes,
and often in association with callipterid foliage. No attachment has been
identified, however, so, at present, their affinities remain unknown.
Calamitalean remains are nearly absent in the red beds facies.
Figure 18.3 is a suspect calamitalean stem, given its strong ribs and
suggestion of a node at the far left hand end. Given its relatively small
size, however, it also may be a Sphenophyllum stem (or not a sphenopsid
at all).
The flabellate, evenly dichotomized specimen illustrated in Figure
281
FIGURE 14. Dicranophyllum cf. gallicum. 14.1, Field photograph; USNM field locality NM2012-03. Plagiozamites cf. planchardii. 14.2, USNM
specimen 558290; USNM locality 43452.
282
FIGURE 15. Pecopteris sp. 15.1, USNM specimen 558291; USNM locality 42263. 15.2, USNM specimen 558292; USNM locality 42334.
283
FIGURE 16. Sphenophyllum sp. 16.1, USNM specimen 558293; USGS locality 8952. 16.2, USNM specimen 558294; USGS locality 8952. Sphenopteris
sp. 16.3, USNM specimen 558295; USNM locality 42264.
284
FIGURE 17. Neuropteris sp. 17.1-17.2, USNM specimen 558279; USNM locality 42264.
18.4 may be a liverwort or an alga. It is one of several such specimens
from the same location as the cf. Glossopteris/Lesleya occurrences, in
northern New Mexico.
DISCUSSION
The Abo red beds and temporally equivalent, lithologically similar
units in central New Mexico are remarkable for the low diversity flora
they yield over such a large area. Based on paleosols and sedimentologi-
cal architecture (Mack, 2003, 2007; Mack et al., 2010), the Abo Forma-
tion red-bed landscape formed under some degree of rhythmicity, likely
reflective of Early Permian, glacial-interglacial cyclicity, which would
have affected regional base-level and climate. The paleogeographic posi-
tion of the Abo beds, in western equatorial Pangea, may have contributed
strongly to this signature, as a result of paleoatmospheric circulation
patterns (Tabor and Poulsen, 2008) that created a strongly monsoonal
climate. Thus, the region likely was marked by moisture seasonality,
varying in its intensity through the duration of any given cycle (repre-
sented by the alternation of paleosols and sandstone-siltstone beds, and,
where present, limestones – Mack, 2007; Krainer and Lucas, 1995; Lucas
et al., 2013).
The monotonous nature of the Abo Formation red-bed flora is
belied by several deposits that are strikingly different from the norm;
these are often dominated by, or enriched in, plants that are not found
widely or, in several cases, at any other sampling sites. The most unusual
of these is a site in the Zuni Mountains of northern New Mexico (USGS
Locality 8931 and USNM locality 43680 - This site was collected by
geologists from the University of New Mexico, prior to 1930, and again
in the 1930s by paleobotanists from the U.S. Geological Survey; unfor-
tunately, we have been unable to relocate the outcrops based on the
limited records remaining). The collection is dominated by a plant that is
very similar to Lesleya, and somewhat less to Glossopteris (Fig. 13) in
its obovate leaf shape. Leaves still in helical attachment to branches
suggest either that the plant grew in stream side environments where it
was buried rapidly in place during floods (in which case the plants
themselves would have been quite small), or that branches were broken
from plants living close to the site of burial and rapidly entombed, pos-
sibly during storms. In the southern part of the state, a single deposit
was found (USNM Locality 42255) that contained a quite peculiar form
of narrow, taeniopterid leaf (Fig. 12.3, 12.4), also possibly in attachment
to stems. The specific identity of this leaf is not known to us. Also in the
south, in the Robledo Mountains, a single deposit was found (USNM
Locality 43662) dominated by the gigantopterid Gigantopteridium
americanum (Fig. 10.2); gigantopterids have been mentioned in various
studies of New Mexico geology (Bachman and Hayes, 1958; Hunt, 1983),
but we identified them from only two collecting sites. These kinds of
occurrences are in keeping with studies of modern landscapes that indi-
cate that most species, even those that are rare in number of occurrences
or average abundance, are somewhere abundant to even locally dominant
(e.g., Murray and Lepschi, 2004).
The question arises about whether the monotony of conifer and
supaioid dominance in the Abo Formation flora is a taphonomic happen-
stance. Both kinds of plants produced very leathery leaves and/or
285
FIGURE 18. Conifer cone? 18.1, USNM specimen 558296; USNM locality 42251. Sporangia of indeterminate affinity. 18.2, USNM specimen 558297;
USNM locality 42251. Calamite stem? 18.3, USNM specimen 558298; USNM locality 42107. Thalloid thallus. 18.4, USNM specimen 536578; USGS
locality 8931.
branches, which presumably were able to withstand some degree of
water transport prior to burial. This is indicated by not-infrequent speci-
mens disposed across bedding planes, especially in fine sandstones with
trough cross bedding, suggesting that the plant litter was rapidly depos-
ited and buried. However, such occurrences are equaled or exceeded by
mats of leaves of both groups, often in clay partings in the upper parts of
fining upward fills of tabular sheet-sand channel belts. Such deposits
indicate limited transport, deposition of large amounts of plant material
under relatively quiet water conditions, probably settling from suspen-
sion. Furthermore, the rare elements in these floras, such as pecopteroids,
neuropterids, or sphenopsids, occur in many cases with the more abun-
dant plants, conifers, in particular, indicating that there does not seem to
have been a persistent taphonomic filter removing them and leaving only
conifers and supaioids. In addition, the rarity of plants that would be
expected to occupy wet floodplains and streamsides, especially the ro-
bustly constructed calamitaleans, common as stem casts in many depo-
sitional environments (DiMichele and Falcon-Lang, 2012), suggests that
they were absent from much of the landscape and confined to quite
geographically and spatially limited wetter areas. In fact, the discovery
at an Abo outcrop in Sierra County New Mexico, of autochthonous
Supaia thinnfeldioides plants in periodically flooded streamside settings,
indicates that these plants could tolerate strongly seasonally dry envi-
ronments while surviving periods of flooding and partial burial (DiMichele
et al., 2012).
As it relates to the possibility that the red-beds flora is simply a
taphonomically filtered version of the same species pool found in the
more diverse gray beds flora, consider the following. Cordaitaleans are
very rare in the red-beds deposits. These plants had very tough, resistant
foliage capable of surviving transport. They also are known as elements
of both coastal peat forming swamps (Raymond et al., 2010) and
extrabasinal areas, under seasonal climates (Falcon-Lang and Bashforth,
2004). Thus, they had very wide environmental tolerances at the clade/
evolutionary lineage level. Were the low diversity and composition of the
red beds floras simply a taphonomic happenstance of transport, one
might expect cordaitaleans to be a prominent part of the flora, especially
since they occur at many gray Abo plant sites. Additionally, the leaves of
supaioids and the branches of conifers are not similar in shape and size,
and probably would not have had similar hydraulic characteristics under
transport. Furthermore, these dominant elements tend to be separate in
most deposits, suggesting that although they lived in proximity on flood-
plains, they probably were habitat differentiated to a fairly strong degree
(DiMichele et al., 2007). And, there are elements of the red-beds floras
that have not been found in the gray beds, including the peculiar “Supaia”
anomala (Figs. 7 and 8), a plant with ribbon-like leaves, the Glossopteris/
Lesleya-like plant from northern New Mexico (Fig. 13), and the
Taeniopteris-like plant from southern New Mexico (Fig. 12). These pat-
terns suggest that there were similarities between the gray and red beds
species pools, but these were different in ways that would not be ex-
pected were taphonomic filtering the sole, or predominant explanation.
ACKNOWLEDGMENTS
The authors thank the Smithsonian Institution, the Bureau of
Land Management, and the Janet Stearns Upjohn Trust for support of
the research that contributed to this paper. We acknowledge the help and
advice of W. John Nelson and Scott D. Elrick of the Illinois State Geo-
logical Survey, University of Illinois, Howard Falcon-Lang of Royal
286
Holloway, University of London, Cindy Looy of the University of
California, Berkeley, Jerry Macdonald of Las Cruces, NM, Justin
Spielmann and Larry Rinehart of the NMMNH, and Karl Krainer of the
University of Innsbruck. We thank Cindy Looy and Arden Bashforth for
providing reviews of the manuscript.
Archangelsky, S. and Wagner, R.H., 1983, Glossopteris anatolica sp. nov.
from uppermost Permian strata in south-east Turkey: Bulletin of the
British Museum–Natural History Geology, v.  37, p. 81–91.
Bachman, G.O. and Hayes, P.T., 1958, Stratigraphy of Upper Pennsylva-
nian and Lower Permian rocks in the Sand Canyon area, Otero County,
New Mexico: Geological Society of America Bulletin, v. 69, p. 689-700.
Barthel, M., 1977, Die Gattung Dicranophyllum GR.'EURY in den
varistischen Innensenken der DDR: Hallesches Jahbuch für
Geowissenschaften, v. 2, p. 73 86.
Barthel, M. and Noll, R., 1999, On the growth habit of Dicranophyllum
hallei Remy et Remy: Veröffentlichungen Naturhistorisches Museum
Schleusingen, v. 14, p. 59-64.
Bassler, H., 1916, A cycadophyte from the North American coal measures:
American Journal of Science, v. 42, p. 21-26.
Broutin J. and Kerp, H., 1994, Aspects of Permian palaeobotany and pa-
lynology. XIV. A new form-genus of broad-leaved Late Carboniferous
and Early Permian Northern Hemisphere conifers: Review of
Palaeobotany and Palynology, v. 83, p. 241–251.
Berthelin, M., Broutin, J., Kerp, H., Crasquin-Soleau, S., Platel, J.P. and
Roger, J., 2003, The Oman Gharif mixed paleoflora: A key tool for
testing Permian Pangea reconstructions: Palaeogeography
Palaeoclimatology Palaeoecology, v. 196, p. 85-98.
Berthelin, M., Stolle, E., Kerp, H. and Broutin, J., 2006, Glossopteris
anatolica Archangelsky and Wagner 1983, in a mixed Middle Permian
flora from the Sultanate of Oman: Comments on the geographical and
stratigraphical distribution: Review of Palaeobotany and Palynology, v.
141, p. 313-317.
Broutin, J., Roger, J., Platel, J.-P., Angiolini, L., Baud, A., Bucher, H.,
Marcoux, J. and Al Hashmi, H., 1995, The Permian Pangea. Phytogeo-
graphic implications of new paleontological discoveries in Oman (Ara-
bian peninsula): Comptes Rendus de l’Académie des Sciences Paris, Série
II a, v. 321, p. 1069-1086.
Cleal, C.J., Uhl, D., Cascales-Miñana, B., Thomas, B.A., Bashforth, A.R.,
King, S.C. and Zodrow, E.L., 2012, Plant biodiversity changes in
Carbonferous tropical wetlands: Earth-Science Reviews, v. 114, p. 124-
155.
Clement-Westerhof, J.A., 1984, Aspects of Permian palaeobotany and pa-
lynology. IV. The conifer Ortiseia Florin from the Val Gardena Forma-
tion of the Dolomites and the Vicentinian Alps (Italy) with a revised
concept of the Walchiaceae (Göppert) Schimper: Review of Palaeobotany
and Palynology, v. 41, p. 51-166.
Delevoryas, T., 1969, Glossopterid leaves from the Middle Jurassic of Oaxaca,
Mexico: Science, v. 165, p. 895-896.
DiMichele, W.A. and Chaney, D.S., 2005, Pennsylvanian-Permian fossil
floras from the Cutler Group, Cañon del Cobre and Arroyo del Agua
areas, in northern New Mexico: New Mexico Museum of Natural His-
tory and Science, Bulletin 31, p. 26-33.
DiMichele, W.A. and Falcon-Lang, H.J., 2012, Calamitalean “pith casts”
reconsidered: Review of Palaeobotany and Palynology, v. 173, p. 1-14.
DiMichele, W.A., Kerp, H., Krings, M. and Chaney, D.S., 2005, The Per-
mian peltasperm radiation: Evidence from the southwestern United
States: New Mexico Museum of Natural History and Science, Bulletin
30, p. 67-79.
DiMichele, W.A., Tabor, N.J., Chaney, D.S. and Nelson, W.J., 2006, From
wetlands to wet spots: Environmental tracking and the fate of Carbon-
iferous elements in Early Permian tropical floras; in Greb, S.F. and
DiMichele, W.A., eds., Wetlands through time: Geological Society of
America, Special Paper 399, p. 223-248.
DiMichele, W.A., Chaney, D.S., Nelson, W.J., Lucas, S.G., Looy, C.V., Quick,
K. and Wang Jun, 2007, A low diversity, seasonal tropical landscape
REFERENCES
dominated by conifers and peltasperms: Early Permian Abo Formation,
New Mexico: Review of Palaeobotany and Palynology, v. 145, p. 249-
273.
DiMichele, W.A., Lucas, S.G. and Krainer, K., 2012, Vertebrate trackways
among a stand of Supaia White plants on an Early Permian floodplain,
New Mexico: Journal of Paleontology, v. 86, p. 584-594.
Falcon-Lang, H.J. and Bashforth, A.R., 2004, Pennsylvanian uplands were
forested by giant cordaitalean trees: Geology, v. 32, p. 417-420.
Falcon-Lang, H.J. and DiMichele, W.A., 2010, What happened to the coal
forests during Pennsylvanian glacial phases?: Palaios, v. 25, p. 611-617.
Falcon-Lang, H.J., Jud, N.A., Nelson, W.J., DiMichele, W.A., Chaney, D.S.
and Lucas, S.G., 2011, Pennsylvanian coniferopsid forests in sabkha
facies reveal the nature of seasonal tropical biome: Geology, v. 39, p.
371-374.
Florin, R., 1939, Die Koniferen des Oberkarbons und des unteren Perms. 3.
Heft: Palaeontographica, v. 85 B, p. 123-173.
Galtier, J. and Broutin, J., 2008, Floras from red beds of the Permian Basin
of Lodève (Southern France): Journal of Iberian Geology, v. 34, p. 57-
72.
Gould, R. and Delevoryas, T., 1977, The biology of Glossopteris: Evidence
from petrified seed-bearing and pollen-bearing organs: Alcheringa, v. 1,
p. 387-399.
Hunt, A., 1983, Plant fossils and lithostratigraphy of the Abo Formation
(Lower Permian) in the Socorro area and plant biostratigraphy of Abo
red beds in New Mexico: New Mexico Geological Society, Guidebook 34,
p. 157-163.
Kerp, J.H.F., 1988, Aspects of Permian palaeobotany and palynology. X.
The West-and Central European species of the genus Autunia Krasser
emend. Kerp (Peltaspermaceae) and the form-genus Rhachiphyllum
Kerp (callipterid foliage): Review of Palaeobotany and Palynology, v.
54, p. 249-360.
Kerp, H., 1996, Post-Variscan late Palaeozoic Northern Hemisphere gym-
nosperms: The onset to the Mesozoic: Review of Palaeobotany and
Palynology, v. 90, p. 263-285.
Kerp, H. and Fichter, J., 1985, Die Makrofloren des saarpfälzischen
Rotliegenden (?Ober-Karbon-Unter-Perm; SW-Deutschland): Mainzer
Geowissenschaftliche Mitteilungen, v. 14, p. 159–286.
Kerp, J.H.F., Poort, R.J., Swinkels, H.A.J.M. and Verwer, R. , 1990, Aspects
of Permian palaeobotany and palynology. IX. Conifer-dominated
Rotliegend floras from the Saar-Nahe Basin (?Late Carboniferous - Early
Permian; SW-Germany) with special reference to the reproductive biol-
ogy of the earliest conifers: Review of Palaeobotany and Palynology, v.
62, p. 205-248.
Kottlowski, F.E., Flower, R.H., Thompson, M.L. and Foster, R.W., 1956,
Stratigraphic studies of the San Andres Mountains, New Mexico: New
Mexico Bureau of Mines and Mineral Resources, Memoir 1, 132 p.
Krainer, K. and Lucas, S.G., 1995, The limestone facies of the Abo–Hueco
transitional zone in the Robledo Mountains, southern New Mexico: New
Mexico Museum of Natural History and Science, Bulletin 6, p. 33-38.
Krainer, K., Vachard, D. and Lucas, S.G., 2009, Facies, microfossils (smaller
foraminifers, calcarerous algae) and biostratigraphy of the Hueco Group,
Doña Ana Mountains, southern New Mexico, USA: Revista Italiana di
Paleontologia e Stratigrafia, v. 115, p. 3-26.
Krings, M., Klavins, S.D., DiMichele, W.A., Kerp, H. and Taylor, T.N.,
2005, Epidermal anatomy of Glenopteris splendens Sellards nov. emend.,
an enigmatic seed plant from the Lower Permian of Kansas (U.S.A.):
Review of Palaeobotany and Palynology, v. 136, p. 159-180.
Leary, R.L., 1990, Possible Early Pennsylvanian ancestor of the Cycadales:
Science, v. 249, p. 1152-1154.
Lucas, S.G. and Heckert, A.B., eds., 1995, Early Permian footrprints and
287
facies: New Mexico Museum of Natural History and Science, Bulletin 6,
301 p.
Lucas, S.G., Anderson, O.J., Heckert, A.B. and Hunt, A.P., 1995, Geology of
Early Permian tracksites, south-central New Mexico: New Mexico Mu-
seum of Natural History and Science, Bulletin 6, p. 13-32.
Lucas, S.G., Rowland, J.M., Kues, B.S., Estep, J.W. and Wilde, G.L., 1999,
Uppermost Pennsylvanian and Permian stratigraphy and biostratigra-
phy at Placitas, New Mexico: New Mexico Geological Society, Guide-
book 50, p. 281-292.
Lucas, S.G., Krainer, K. and Kues, B.S., 2002, Stratigraphy and correlation
of the Lower Permian Hueco Group in the southern San Andres Moun-
tains, Doña Ana County, New Mexico: New Mexico Geological Society,
Guidebook 53, p. 223-240.
Lucas, S.G., Krainer, K. and Colpitts, R.M., 2005, Abo-Yeso (Lower Per-
mian) stratigraphy in central New Mexico: New Mexico Museum of
Natural History and Science, Bulletin 31, p. 101-115.
Lucas, S.G., Spielmann, J.A., Rinehart, L.F. and Martens, T., 2009,
Dimetrodon (Amniota: Synapsida: Sphenacodontidae) from the Lower
Permian Abo Formation, Socorro County, New Mexico: New Mexico
Geological Society, Guidebook 60, p. 281-284.
Lucas, S.G., Krainer, K., Chaney, D.S., DiMichele, W.A., Voigt, S., Berman,
D. and Henrici, A.C., 2012, The Lower Permian Abo Formation in the
Fra Cristobal and Caballo mountains, Sierra County, New Mexico: New
Mexico Geological Society, Guidebook 63, p. 345-376.
Lucas, S.G., Krainer, K., Chaney, D.S., DiMichele, W.A., Voigt, S., Berman,
D.S. and Henrici, A.C., 2013, The Lower Permian Abo Formation in
central New Mexico: New Mexico Museum of Natural History and Sci-
ence, Bulletin 59, this volume.
Mack, G.H., 2003, Lower Permian terrestrial paleoclimatic indicators in
New Mexico and their comparison to paleoclimate models: New Mexico
Geological Society, Guidebook 54, p. 231–240.
Mack, G., 2007, Sequence stratigraphy of the Lower Permian Abo Member
in the Robledo and Doña Ana Mountains near Las Cruces, New Mexico:
New Mexico Geology, v. 29, p. 3-12.
Mack, G.H., Cole, D.R., Giordano, T.H., Schaal, W.C. and Barcelos, J.H.,
1991, Paleoclimatic controls on stable oxygen and carbon isotopes in
caliche of the Abo Formation (Permian), south-central New Mexico,
U.S.A.: Journal of Sedimentary Petrology, v. 61, p. 458–472.
Mack, G.H., Tabor, N.J. and Zollinger, H.J., 2010, Palaeosols and sequence
stratigraphy of the Lower Permian Abo Member, south-central New
Mexico, USA: Sedimentology, v. 57, p. 1566-1583.
Mamay, S.H., 1967, Lower Permian plants from the Arroyo Formation in
Baylor County, north-central Texas: U.S. Geological Survey, Profes-
sional Paper 575-C, p. C120-C126.
Mamay, S.H., 1981, An unusual new species of Dicranophyllum Grand’Eury
from the Virgilian (Upper Pennsylvanian) of New Mexico, U.S.A.: The
Palaeobotanist, v. 28-29, p. 86-92.
Mamay, S.H., 1990, Charliea manzanitana, n. gen. n. sp, and other enig-
matic parallel–veined foliar forms from the Upper Pennsylvanian of
New Mexico and Texas: American Journal of Botany, v. 77, p. 858–866.
Mamay, S.H., Chaney, D.S. and DiMichele, W.A., 2009, Comia, a seed plant
possibly of peltaspermous affinity: A brief review of the genus and
description of two new species from the Early Permian (Artinskian) of
Texas, C. greggii sp. nov. and C. craddockii sp. nov.: International
Journal of Plant Sciences, v. 170, p. 267-282.
Mapes G. and Rothwell, G.W., 1991, Structure and relationships of primi-
tive conifers: Neues Jahrbuch für Geologie und Paläontologie
Abhandlungen, v. 183, p. 269–287.
Murray, B.R. and Lepschi, B.J., 2004, Are locally rare species abundant
elsewhere in their geographical range?: Austral Ecology, v. 29, p. 287-
293.
Naugolnykh, S.V., 1999, A new species of Compsopteris Zalessky from the
the Upper Permian of the Kama River Basin (Perm Region): Paleonto-
logical Journal, v. 33, p. 686-697.
Plotnick, R.E., Kenig, F., Scott, A.C., Glasspool, I.J., Eble, C.F. and Lang,
W.J., 2009, Pennsylvanian paleokarst and cave fills from northern
Illinois, USA: A window into Late Carboniferous environments and land-
scapes: Palaios, v. 24, p. 627-637.
Pray, L.C., 1961, Geology of the Sacramento Mountains escarpment, Otero
County, New Mexico: New Mexico Bureau of Mines and Mineral Re-
sources, Bulletin 35, 144 p.
Raymond, A., Lambert, L., Costanza, S., Slone, E.J. and Cutlip, P.C., 2010,
Cordaiteans in paleotropical wetlands: An ecological re-evaluation: In-
ternational Journal of Coal Geology, v. 83, p. 248-265.
Remy, W. and Remy, R., 1975, Beiträge zur Kenntnis des Morpho-Genus
Taeniopteris Brongniart: Argumenta Palaeobotanica, v. 4, p. 31-37.
Rothwell, G.W. and Mapes, G., 2001, Barthelia furcata gen. et sp. nov., with
a review of Paleozoic coniferophytes and a discussion of coniferophyte
systematics: International Journal of Plant Sciences, v. 162, p. 637–
667.
Tabor, N.J. and Poulsen, C. J., 2008, Palaeoclimate across the Late Penn-
sylvanian–Early Permian tropical palaeolatitudes: A review of climate
indicators, their distribution, and relation to palaeophysiographic cli-
mate factors: Palaeogeography, Palaeoclimatology, Palaeoecology, v.
268, p. 293-310.
Tabor, N.J., Romanchock, C.M., Looy, C.V., Hotton, C.L., DiMichele,
W.A. and Chaney, D.S., 2013, Conservatism of Late Pennsylvanian
vegetational patterns during short-term cyclic and long-term directional
environmental change, western equatorial Pangaea: Journal of the Geo-
logical Society, in press.
Tidwell, W.D. and Ash, S.R., 2003, Revision and description of two new
species of Charliea Mamay from Pennsylvanian strata in New Mexico
and Utah, USA: Review of Palaeobotany and Palynology, v. 124, p.
297-306.
Tidwell, W.D. and Ash, S.R., 2004, Synopsis of the flora in the Red Tanks
Formation, Carrizo Arroyo, New Mexico: New Mexico Museum of Natu-
ral History and Science, Bulletin 25, p. 97-103.
Visscher H., Kerp, J.H.F. and Clement-Westerhof, J.A., 1986, Aspects of
Permian palaeobotany and palynology. VI. Towards a flexible system of
naming Paleozoic conifers: Acta Botanica Neerlandica v. 35, p. 87–99.
Voigt, S., Lucas, S.G. and Krainer, K., 2013. Coastal-plain origin of trace-
fossil bearing red beds in the Early Permian of southern New Mexico,
U.S.A.: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 369, p.
323-334.
Wagner, R.H., 1962, On mixed Cathaysia and Gondwana flora from SE
Anatolia (Turkey): Compte Rendu Quatrième Congrès pour
l’Avancement des Ètudes de Stratigraphie et de Géologie du Carbonifère,
Heerlen 15-20 September 1958, v. 3, p. 745–752.
Wagner, R.H. 2005, Dicranophyllum glabrum (Dawson) Stopes, an unusual
element of lower Westphalian floras in Atlantic Canada: Revista Española
de Paleontología, v. 20, p. 7-13.
Wagner, R.H. and Martínez García, E., l982. Description of an Early Per-
mian flora from Asturias and comments on similar occurrences in the
Iberian Peninsula: Trabajos de Geologia, Universidad de Oviedo, v. 12, p.
273-287.
Wang, J., Pfefferkorn, H.W. and Bek, J., 2009, Paratingia wudensis sp.
nov., a whole noeggerathialean plant preserved in an earliest Permian
air fall tuff in Inner Mongolia, China: American Journal of Botany, v.
96, p. 1676-1689.
White, D., 1929, Flora of the Hermit Shale, Grand Canyon, Arizona:
Carnegie Institution of Washington Publication, v. 405, p. 1-221.
288
Near Gallina Well, northeast of Socorro, a typical section of the lower part of the Lower Permian Abo Formation consists of red-bed mudstones and
crossbedded sandstones. These are strata of fluvial origin. Note the lenticularity of the large sandstone channel complex in the foreground.