Journal of Vertebrate Paleontology 27(4):1039-1042, December 2007 ? 2007 by the Society of Vertebrate Paleontology SHORT COMMUNICATION FIRST ATLANTIC RECORD OF THE PUFFIN CERORHINCA (AVES, ALCIDAE) FROM THE PLIOCENE OF NORTH CAROLINA N. ADAM SMITH,"-' STORRS L. OLSON,^ and JULIA A. CLARKE^'^; ^North Carolina State University, Department of Marine, Eartli and Atmospheric Sciences, Campus Box 8208, Raleigli, Nortii Carolina 27695-8208 U.S.A., adam_smith@ncsu.edu; ^National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia 20560-0131 U.S.A., olson@si.edu; ^North Carolina Museum of Natural Sciences, 11 West Jones St., Raleigh, North Carolina 27601-1029 U.S.A., julia_clarke@ncsu.edu. The Alcidae are pelagic, wing-propelled diving birds belong- ing to the order Charadriiformes and are considered to be the northern hemispherical equivalent of penguins (Storer, 1960). The Alcidae comprises 11 extant genera and 23 species of Hol- arctic distribution (del Hoyo et al., 1996). Fraterculini (puffins), consisting of the Cerorhinca and Fratercula has been supported as monophyletic (Strauch, 1985; Sibley and Ahlquist, 1990; Moum et al., 1994; Friesen et al., 1996) and has been proposed to be the sister-group to all other alcids (Strauch, 1985; Chandler, 1990b). Extant diversity of puffins includes three Pacific species (Fratercula comiculata, Fratercula cirrhata, C. monocerata) and a single species in the Atlantic (Fratercula ?rctica). The only extant representative of Cerorhinca, the Rhinoceros Auklet C. monocerata, and all previously known fossils are from the Pacific basin (Olson, 1985d). Three fossil species of Cero- rhinca, as well as additional material tentatively referred to Ce- rorhinca (Table2), are known from the middle Miocene to late Pliocene of southern California and northern Mexico. Among Pliocene material recovered from the PCS Phosphate mine in Aurora, North Carolina (Fig. 1), Olson and Rasmussen (2001) recognized remains of two species of Fratercula, the At- lantic Puffin F. aff. ?rctica and the Tufted Puffin F. aff. cirrhata. Recent re-examination of the material assigned to F. aff. cirrhata indicated that this material was a composite series of two distinct taxa. One complete and two proximal humeri are instead refer- able to Cerorhinca, thus providing the first record of the genus from the Atlantic basin. The remaining 29 specimens were con- firmed as F. cf. cirrhata. Materials and Methods?In the description, the English equivalents of the Latin osteological nomenclature of Baumel and Witmer (1993) are used. With the exception of the terms anterior and posterior substituted for cranial and caudal, respec- tively, the terms used for the anatomical orientation of a bird are those used by Clark (1993). Measurements follow those of Von den Driesch (1976). All measurements were taken using digital calipers and rounded to the nearest tenth of a millimeter. Institutional Abbreviations?NCSM, North Carolina Mu- seum of Natural Sciences, Raleigh, North Carolina; SDSNH, San Diego Natural History Museum, San Diego, California; USNM, National Museum of Natural History, Smithsonian Institution, Washington, D.C. Geologic Setting?The PCS Phosphate Mine (formerly known as the Lee Creek Mine; Olson and Rasmussen, 2001) is located along the south shore of the Pamlico River and exposes an unconformable sequence of middle Miocene and early Pliocene sediments, conformably overlain by Pleistocene aged sediments (Gibson, 1983). An age of 4.4 ? 0.2 Ma (early Pliocene) has been assigned to the Yorktown Fm. based on K/Ar dating of the Orionina vaughani assemblage zone, and correlated with planktonic foraminifera Zone N19 (Hazel, 1983). No mi- crofossils are preserved in association with the new Cerorhinca remains, which could be used to precisely date the specimens. However, the preservation of the Cerorhinca fossils closely matches that of twelve other avian specimens (e.g., USNM 178084, 178150, 193334) referred to the Pliocene Yorktown Fm. 35?- fJ Skl^?i^=^ I y^^^ PA J^ J^ ^_rv r If '^^ jf Ix^ /\V. ^^ V / wv . ?< V / VA fy 7^ ^ ATLANTIC / ' OCEAN U L NC 3^ PCS-"'^ fci"^^^ Pamlico Sound N sc JV -/ ? '^ 1 ? 100 km 1 'Corresponding author. 80? FIGURE 1. Map of eastern USA indicating the locality of PCS Phos- phate mine near Aurora, NC where the specimens were collected. Shaded area denotes the subsurface extent of Unit 1 of the Yorktown Formation. (Altered from Gibson, 1983). 1039 1040 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 27, NO. 4, 2007 on the basis of the foraminiferal assemblage derived from matrix associated with those specimens (Gibson, 1975, unpubl. data). Avian fossils from the Pungo River Fm. are also often charac- terized by a black phosphatic patina, which is not present in the Cerorhinca specimens reported here. The absence of Fratercula and Cerorhinca in coeval Miocene sediments of the Calvert For- mation in Maryland, which also contain fossil alcids (Olson and Rasmussen, 2001), is also consistent with a Pliocene Yorktown Fm. provenance. However, because the Cerorhinca remains were not collected in-situ, the possibility that they are from the older, middle Miocene, Pungo River Fm. cannot be entirely ruled out. SYSTEMATIC PALEONTOLOGY AVES LINNAEUS, 1758 CHARADRIIFORMES HUXLEY, 1867 ALGIDAE VIGORS, 1825 FRATERCULINI STORER, 1960 CERORHINCA BONAPARTE, 1831 CERORHINCA sp. Referred Material?USNM 257520, complete left hum?rus (Fig. 2; Table 1); USNM 459395, proximal end of right hum?rus (Fig. 3; Table 1); USNM 193051, proximal end of right hum?rus (Fig. 3; Table 1). Comparative Material?Cerorhinca monocerata (USNM: 557613, 557614, 561468, 620641, 620643); Fratercula ?rctica (USNM: 18055, 18057, 18058, 224189, 621321); Fratercula cir- rhata (USNM: 19449, 488748; NCSM: 17823, 18099, 18100); Fra- tercula corniculata (USNM: 499961, 499964; NCSM: 17835, 18083, 18388). Differential Diagnosis?Cerorhinca is included in Fratercu- lini, a subclade within Alcidae (Storer, 1960), the monophyly of which has been supported by analyses of molecular (Sibley and Ahlquist, 1990; Moum et al., 1994; Friesen et al, 1996; Moum et al., 2002) and morphological data (Strauch, 1985; Chandler, 1990b). The humeri of the Fraterculini differ from other alcids in having a well-excavated second pneumatic fossa (Strauch, 1978, 1985; Chandler, 1990a), a condition similar to that in the nearest outgroup taxa of Alcidae (e.g., Larinae, Sterninae; Strauch, 1978; Sibley and Ahlquist, 1990), in which the second pneumatic fossa is extensively excavated. However, the condition observed in Fraterculini differs from that in the nearest outgroup taxa, in which the second pneumatic fossa is separated from the dorsal tubercle by the margo caudalis (Baumel and Witmer, 1993). In Fraterculini, the margo caudalis is absent, and the dorsal tubercle is developed as a distally extending scar (crista m. supracora- coidei; Baumel and Witmer, 1993:pg. 98), which is bordered ven- trally by the steeply angled dorsal margin of the second pneu- matic fossa. Cerorhinca differs from Fratercula on the basis of three distinguishing characters of the hum?rus: (1) the pneu- matic fossa (fossa pneumotricipitalis; Baumel & Witmer, 1993) of Cerorhinca and Fratercula is divided into two separate fossae. the second or dorsal of which is the site of origination of the dorsal head of the humerotriceps muscle (Baumel and Witmer, 1993) and is considerably less excavated in Cerorhinca than in Fratercula; (2) depression on the distal surface of the ventral tubercle deeper than Fratercula (Olson and Rasmussen, 2001); (3) in ventral view, the lateral margin of the ventral tubercle of Cerorhinca is characterized by two distinct concavities, whereas in Fratercula, this margin is a single concave curvature. The spe- cies level relationships among the three named extinct and one extant Pacific species of Cerorhinca and that represented by the Atlantic fossils will be evaluated in a broader taxonomic assess- ment of the validity of previously named Fraterculini species and of the phylogenetic relationships among all Alcidae species in- cluding all of the Fraterculini, (Smith, in prep.). Only the holo- type specimens of the two extinct species C. real and C. minor (Table 2) are directly comparable to the new Cerorhinca sp. humeri described here. Cerorhinca dubia is known only from associated leg elements and material identified as Cerorhinca sp. of Howard (1968) and Chandler (1990a) are ulnae. DESCRIPTION The fossils referred to Cerorhinca differ only slightly in mor- phology (Fig. 2) and size (Table 1) from specimens of the extant species C. monocerata. In the complete hum?rus USNM 257520 the proximal end of the dorsal supracondylar process contacts the shaft at a -120? angle, whereas in C. monocerata, the angle is more acute at -90?. The dorsal condyle of the fossil specimen is more rounded dorsally than that of C. monocerata. The ventral side of the ventral condyle of USNM 257520 is more flattened than the condition observed in C. monocerata. The size range observed among the new remains (Table 1) is within the range of statistically determined size variation observed in modern alcids (Bedard, 1985; Burness and Montevecchi, 1992). All three specimens display the anteroposteriorly flattened hu- meral shafts characteristic of many wing-propelled divers and of all Alcidae. In posterior view the proximal ends of the new Ce- rorhinca humeri are characterized by a proximoventrally broad- ening dorsal tubercle (i.e., crista m. supracoracoidei), although the proximal end of the dorsal tubercle of Cerorhinca is less ventrally expanded than that of F. cirrhata (Fig 2). In contrast to other alcids (e.g.. Alca, Uria) the pneumatic fossa is a deep ex- cavation with a narrow distal margin and a broader ventral mar- gin that merges with the base of the ventral tubercle. The bra- chial depression is a distinct proximally narrowing scar that ex- tends proximally only slightly past the proximal extent of the dorsal supracondylar process. DISCUSSION The puffins (Fraterculini) are thought to have originated in the Pacific primarily because of their greater diversity there (Storer, 1960; Olson, 1985d). Their fossil record in the Pacific extends at TABLE 1. Measurements of Puffin humeri (in mm). Taxa Specimen # GI Bp Dip Sc Bd Dd Cerorhinca sp.* USNM 257520 67.2 14.9 14.1 57 10.5 7.5 Cerorhinca sp.* USNM 459395 ? 15.8 15.3 ? ? ? Cerorhinca sp.* USNM 193051 ? 15.6 15.4 ? ? ? Cerorhinca monocerata USNM 620643 70.0 14.4 14.3 5.7 lOJ 7.4 Fratercula cirrhata NCSM 177823 77.0 16.0 15.8 6.0 11.5 8.3 Fratercula ?rctica USNM 292346 67.2 14.0 13.1 4.8 9.8 6.8 Fratercula corniculata NCSM 18388 69.9 15.0 14.9 5.3 lOJ 7.7 Measurements according to Von den Driesch, 1976. *Denotes fossil specimens. Abbreviations: Bd, breadth of the distal end; Bp, breadth of proximal end; Dd, distal diagonal; Dip, diagonal of proximal end; GI, greatest length; Sc, smallest breadth of corpus (shaft). SHORT COMMUNICATIONS 1041 TABLE 2. Published specimens referred to Cerorhinca. Taxa Material Provenience Age Reference Cerorhinca dubia associated legs California Middle Miocene Miller, 1925 Cerorhinca sp. proximal ulna California Late Miocene Howard, 1968 Cerorhinca minor wing elements Mexico Middle Pliocene Howard, 1971 Cerorhinca real wing elements California Late Pliocene Chandler, 1990a Cerorhinca sp. right ulna California Late Pliocene Chandler, 1990a least as far back as the middle Miocene (Miller, 1925), whereas in the Atlantic there are no records from the Miocene (Olson and Rasmussen, 2001). The occurrence of Cerorhinca in the At- lantic documented here, in addition to previously reported Fra- terculini taxa (Miller, 1925; Howard, 1968, 1971; Chandler, 1990a) indicates that the diversity of puffins was as great in the Atlantic in the early Pliocene as it is in the Pacific today. This diversity has been proposed to have been achieved rapidly dur- ing the mid Miocene to early Pliocene, presumably indicating an influx of three separate lineages of puffins {Cerorhinca plus two Fratercula) from the Pacific through a northern passage between the oceans (Olson and Rasmussen, 2001), although a southern route of dispersal cannot be ruled out as the Panamanian Seaway remained open until -2.5 Ma (Warheit, 2002). Just as climate changes in the middle Miocene (-11-16 mya) are proposed to have influenced the initial diversification of alcids (Warheit, 2002), major oc?anographie changes in the late Pliocene (-2.9 FIGURE 2. Comparison of Fraterculini humeri in posterior view. A, Cerorhinca sp. (USNM 257520); B, Cerorhinca monocerata (USNM 620643); C, Fratercula cirrhata (USNM 459395). Anatomical Abbrevia- tions: dt, dorsal tubercle; pfl, pneumatic fossa one; pf2, pneumatic fossa two. Ma) due in part to closure of the Panamanian Seaway and the onset of severe glacial cycles in the North Atlantic (Bartoli et al., 2005), the smallest of the world's ocean basins (Briggs, 1970), also may have played a role in the evolutionary history of the Alci- dae. Factors such as changing salinities, temperatures, current patterns, and the faunal turnover of pelagic invertebrates asso- ciated with these factors, caused the Atlantic to become a much less hospitable place for many organisms (Bartoli et al., 2005). The drop in sea level in southern parts of the North Atlantic, estimated at -85 m by Krantz (1991), would have resulted in a regression of the shoreline many kilometers away from the once near-shore breeding grounds of puffins. Additionally, the forma- tion of ice on more northern shores associated with the onset of glaciation would have obstructed the traditional breeding grounds of puffins along the Atlantic coast (Olson and Rasmus- sen, 2001). Although extant Pacific Fratercula and C. monocerata both forage for fish and small invertebrates at similar depths, the range of C. monocerata does not extend as far north as that of F. corniculata or F. cirrhata, and extends further south (del Hoyo et al., 1996). Extreme climate changes associated with the final clos- ing of the Panamanian Isthmus led to dramatic faunal shifts to the south during the middle Pliocene (Bartoli et al., 2005). These climate changes, linked with a preference for warmer waters, may have contributed to the extinction of Cerorhinca in the At- lantic. Extinctions and retractions in range were also rampant during the Pleistocene and overall diversity of seabirds in general and alcids in particular was greatly reduced (Emslie, 1998; Olson and Rasmussen, 2001). To the growing list of North Atlantic disap- pearances recognized by ornithologists, we can now add Cero- rhinca. The biogeographical implications of this discovery will B / 1 cm FIGURE 3. Proximal ends of right humeri. A, posterior view (USNM 459395); B, anterior view (USNM 193051). 1042 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 27, NO. 4, 2007 become clearer only after the phylogenetic relationships among all extant and extinct Fraterculini species have been resolved. Acknowledgments?We thank V. Schneider and B. Browning for access to comparative material at the NCSM, M. Florence and J. Dean for collections assistance at USNM, PCS Phosphate Mine for allowing continued collection of fossils from this im- portant site, and dedicated amateurs such as P.J. Harmatuck and R. Douglas who have donated hundreds of specimens for study. A grant from the Smithsonian Institution Office of Fellowships to N. Adam Smith is gratefully acknowledged. LITERATURE CITED Bartoli, G., M. Sarnthein, M. Weinelt, H. Erlenkeuser, D. Garbe- Schonberg, and D. W. Lea. 2005. Final closure of Panama and the onset of northern hemisphere glaciation. Earth and Planetary Sci- ence Letters 237:33-44. 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