1 This Is a Postprint That Has Been Peer Reviewed and Published in Biology Letters
1 This is a postprint that has been peer reviewed and published in Biology Letters. The
2 final, published version of this article is available online. Please check the final
3 publication record for the latest revisions to this article.
4
5 Boessenecker, R.W., and M. Churchill, and J.H. Geisler. 2015. The oldest known fur
6 seal. Biology Letters 11:2:20140835 doi: 10.1098/rsbl.2014.0835
1
7 The oldest known fur seal
8
9 Robert W. Boessenecker 1,2
10 Morgan Churchill 3,4
11 1Department of Geology, University of Otago, Dunedin, New Zealand 9010
12 2Museum of Paleontology, University of California, Berkeley, California, U.S.A.
13 94720
14 3Department of Geology and Geophysics, University of Wyoming, Laramie,
15 Wyoming, U.S.A.
16 4Program in Ecology, University of Wyoming, Laramie, Wyoming, U.S.A.
17
18 Abstract
19 The poorly known fossil record of fur seals and sea lions (Otariidae) does not reflect
20 their current diversity and widespread abundance. This limited fossil record contrasts
21 with the more complete fossil records of other pinnipeds such as walruses
22 (Odobenidae). The oldest known otariids appear 5 6 Ma after the earliest odobenids,
23 and the remarkably derived craniodental morphology of otariids offers few clues to
24 their early evolutionary history and phylogenetic affinities among pinnipeds. We
25 report a new otariid, Eotaria crypta , from the early middle Miocene “Topanga”
26 Formation (15 17.5 Ma) of southern California, represented by a partial mandible
27 with well preserved dentition. Eotaria crypta is geochronologically intermediate
28 between “enaliarctine” stem pinnipedimorphs (16.6 27 Ma) and previously described
29 otariid fossils (7.3 12.5 Ma), as well as morphologically intermediate by retaining an
30 M2 and a reduced M 1 metaconid cusp and lacking P 2 4 metaconid cusps. Eotaria
2
31 crypta eliminates the otariid ghost lineage and confirms that otariids evolved from an
32 “enaliarctine” like ancestor.
33
34 Keywords: Otariidae, Miocene, Pinnipedia, North Pacific
35
36 1. Introduction
37 Modern fur seals and sea lions (Otariidae) are a clade of pinnipeds characterized by
38 shelf like supraorbital processes on the skull, loss of M 2, and a simplified dentition [1,
39 2]. Although most extant otariids (11 of 16 species) are restricted to the southern
40 hemisphere, prior fossil evidence indicates a North Pacific center of origin for the
41 clade [2 4]. Other crown pinnipeds, including their sister group Odobenidae
42 (walruses), are well represented within middle Miocene assemblages worldwide [3, 5].
43 In contrast, otariids first appear in the early late Miocene [4, 6] and a 5 6 Ma gap
44 exists between the oldest described otariids and the oldest odobenids [4, 6, 7],
45 indicating a significant ghost lineage for Otariidae. A century of extensive sampling
46 and study of middle Miocene marine vertebrate assemblages from the Pacific coast of
47 North America has otherwise failed to unearth other fossils of true otariids, including
48 the robustly sampled Sharktooth Hill Bonebed. Kohno [8] remarked upon the rarity of
49 middle Miocene otariids, and hypothesized that the earliest otariids may have been
50 primarily pelagic in distribution, only rarely straying into shallow marine coastal
51 regions where preservation potential is higher.
52 Otariids are diagnosed by few cranial and postcranial synapomorphies and
53 many simplified (or lost) dental features, in concert with primitively retained
54 postcranial features [9]. The morphological conservatism of fossil and extant otariids
55 hinders interpretation of their early evolution. We report a new genus and species of
3
56 stem otariid, Eotaria crypta , based on a partial mandible with well preserved
57 dentition (Fig. 1) from the early middle Miocene “Topanga” Formation of southern
58 California. Eotaria is morphologically intermediate between previously described
59 fossil otariids and stem pinnipedimorphs, thereby filling a morphological gap in our
60 understanding of pinniped evolution and elucidating the early dental evolution of
61 Otariidae. Eotaria is also geochronologically intermediate and eliminates the otariid
62 ghost lineage.
63
64 2. Material and Methods
65 The new fossil resides in collections of the John D. Cooper Archaeological and
66 Paleontological Center (Orange County Paleontological Collection; OCPC). The
67 holotype specimen (OCPC 5710) was collected from the “Topanga” Formation in
68 Mission Viejo, Orange County, California, which has produced marine birds, other
69 pinnipeds (Allodesmus sp., Pelagiarctos sp.), and dolphins (Kentriodon sp., cf.
70 Zarhinocetus errabundus ) [10, 11]. Age determinations for the “Topanga” Formation
71 include a 15.8 ± 1.3 Ma K/Ar date from andesite near the base of the Paulerino
72 Member of the “Topanga” Formation to the west in the San Joaquin Hills [12] and
73 land mammals from Oso Reservoir [13] indicating a late Hemingfordian (15.9 17.5
74 Ma) to Barstovian (12.5 15.9 Ma) Land Mammal Age [14]. The finest local age
75 control is provided by foraminifera of the Relizian and lower Luisian zones (Raschke
76 1984) which indicate an age of 14.9 17.1 Ma [15] for the “Topanga” Formation in
77 Orange County.
78 To determine phylogenetic placement of Eotaria crypta , we performed a
79 phylogenetic analysis of 115 morphological characters (modified from earlier studies
80 [2, 9, 10, 16] and including 3 novel characters) coded for 23 taxa representing all
4
81 families and all contemporary pinnipeds (Supplementary Information). Character
82 sampling was focused on those characters most useful for resolving the phylogenetic
83 relationships of stem otariids and early pinnipeds, and coding focused on male
84 specimens to minimize effects of sexual dimorphism. A polymorphic character coding
85 method was used to accommodate intra taxon character variation [17]. We also
86 employed polymorphic coding [17] to accommodate widespread individual variation
87 in pinnipeds [2]. Phylogenetic analyses were carried out in TnT [18], using 10,000
88 replicates with sectorial and tree fusing options and with equal and implied weighting
89 (K=2 6); analyses utilizing both a constrained and unconstrained topology were
90 executed (Appendix).
91
92 3. Systematic Palaeontology
93
94 Eotaria crypta gen. et sp. nov.
95 Etymology. The generic name is from the Greek Otaria , the name of the type genus
96 of the family Otariidae and referring to the diminutive external ear of sea lions, plus
97 the Greek eos, meaning dawn and referring to the early age of this new genus. The
98 species name is from the Greek kryptos , meaning hidden, and referring to the rarity of
99 middle Miocene otariids.
100 Holotype. OCPC 5710, a partial right mandible including P2 4, M 1, and M 2 alveolus.
101 Type Locality and Horizon. Early middle Miocene (Burdigalian Langhian)
102 “Topanga” Formation, Mission Viejo, Orange County, California.
103 Diagnosis. A diminutive otariid that differs from all other members of the family in
104 combined possession of these features: M 1 anteroposteriorly longer than premolars,
105 reduced metaconid cusp present, and a reduced M 2 present.
5
106
107 4. Morphology and Phylogeny
108 The ramus is transversely narrow and tabular in shape with a shallow masseteric fossa,
109 a minute crest like genial tuberosity positioned below P 2, and several small mental
110 foramina; a distinct ventral crest for digastric insertion is absent. P 2 M1 are double
111 rooted, while the M 2 bears a single small, circular alveolus. P 2 P4 crowns are high
112 crowned, morphologically similar to one another, lanceolate, and dominated by the
113 protoconid. The paraconid and hypoconid are developed as minute anterior and
114 posterior accessory cusps (respectively). The hypoconid is almost absent in P 2. The
115 M1 is anteroposteriorly longer than P2, but the protoconid is not as high; it bears a
116 similar paraconid, and a more strongly developed and posterodorsally oriented
117 hypoconid. A vestigial metaconid cusp is present on the basal heel of the posterior
118 crista of the M 1 protoconid; this cusp is absent on premolars. All teeth bear a smooth
119 crest like lingual cingulum. The mandible of Eotaria crypta is relatively small and
120 comparable in size to mandibles of adult Arctocephalus philippii and the extinct
121 otariid Pithanotaria starri . Eotaria crypta differs from all other otariids (extinct and
122 extant) in primitively retaining a M2 and reduced metaconid cusp on M 1 .
123 Constrained and non constrained phylogenetic analyses produced identical
124 trees, with Eotaria crypta recovered as the sister taxon to a clade comprising all other
125 otariids. (Fig. 2). One most parsimonious tree was recovered (Retention index (RI) =
126 0.56, Consistency Index (CI) = 0.45, tree length = 47.69). A K value of 3 for implied
127 weighting was generally found to be the most optimal weighting scheme; variation in
128 K generally didn’t affect the placement of Eotaria crypta , but did influence odobenid
129 monophyly. Weaker weighting schemes recovered Odobenidae as paraphyletic, with
130 Odobenus embedded within crown Otariidae, and the remaining walruses reduced to
6
131 an assemblage of stem taxa outside of a clade comprising Phocidae, Desmatophocidae,
132 and Otariidae.
133 A clade comprising Eotaria crypta and all other otariids was supported by two
134 unambiguous synapomorphies: postcanine crowns which are transversely narrow,
135 equidimensional, and anteroposteriorly shorter than high (character 74); and
136 postcanine teeth with reduced metaconid cusp and concave posterior margin of the
137 protoconid (character 94) All later diverging otariids were united by the absence of
138 M2 (character 98).
139
140 4. Discussion
141 Dentition of Eotaria crypta is morphologically intermediate between “enaliarctine”
142 stem pinnipedimorphs (e.g. Enaliarctos , Pteronarctos ) and extant otariids. Eotaria
143 crypta lacks a trenchant paraconid cusp as in “enaliarctines,” but primitively retains a
144 metaconid cusp (albeit reduced and positioned basally), limited heterodonty of the
145 postcanines, and an M 2. Because all later otariids (fossil and modern) are more
146 dentally derived, Eotaria crypta provides dental evidence for the derivation of otariids
147 from an “enaliarctine” like ancestor. Significantly, Eotaria crypta is also
148 geochronologically intermediate between late surviving “enaliarctines” (e.g.
149 Pteronarctos goedertae , Astoria Formation, Oregon, USA; 16.6 20.2 Ma) and the
150 earliest published fossil otariids (Otariidae indet., Aoki Formation, Japan, 11.8 12.5
151 Ma [6]; Pithanotaria starri , Monterey Formation and Santa Margarita Sandstone,
152 California, USA; 7.3 10 Ma; see Supplementary Information). Discovery of Eotaria
153 crypta eliminates a 5 6 Ma ghost lineage for the Otariidae, formerly defined by the
154 gap between Proneotherium repenningi (16.6 17.3 Ma [19]) and the Aoki Formation
155 otariid (11.8 12.5 Ma [6]). Formerly, Barnes [7] hypothesized that the “enaliarctine”
7
156 Pteronarctos goedertae represented an early diverging otariid that filled the temporal
157 gap (10 19.1 Ma) between Enaliarctos and Pithanotaria ; however, cladistic analysis
158 ([9, 10, 20]; this study) conclusively demonstrates that Pteronarctos lies outside
159 crown Pinnipedia.
160 Although Eotaria crypta convincingly demonstrates that otariids evolved
161 within the North Pacific, it represents the entire published fossil record of middle
162 Miocene otariids. Eotaria crypta was collected from the “Topanga” Formation along
163 the Pacific coast, while the more intensely sampled Sharktooth Hill Bonebed was
164 deposited within a large restricted embayment in the San Joaquin basin [21],
165 provisionally supporting Kohno’s [8] hypothesis that the earliest stem otariids were
166 pelagic in distribution. Perhaps adaptation to pelagic (rather than coastal)
167 environments facilitated the early divergence (and later success) of otariids.
168
169 Acknowledgements
170 Thanks to three anonymous reviewers and the editor for constructive comments. We
171 wish to thank J.F. Parham and M. Rivin for access to OCPC collections. We also
172 thank the Rivin family for their hospitality and M. Couffer for collecting and donating
173 the Eotaria crypta holotype. This study also benefited greatly from comments by J.F.
174 Parham, Y. Tanaka, and C. H. Tsai. RWB was supported during this study by a
175 University of Otago Doctoral Scholarship.
176
177 Author contributions .
178 R.W.B. and M.C. designed the research, collected data, and wrote the paper; M.C.
179 conducted the phylogenetic analysis.
180
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181 Funding statement.
182 R.W.B. was supported by a University of Otago Doctoral Scholarship.
183
184 Competing interests.
185 Authors have declared that no competing interests exist.
186
187 References
188 [1] King, J.E. 1983 Seals of the World . London and Oxford, British Museum (Natural 189 History) and Oxford University Press; 240 p. 190 [2] Churchill, M., Boessenecker, R.W. & Clementz, M.T. 2014 Colonization of the 191 Southern Hemisphere by fur seals and sea lions (Carnivora: Otariidae), revealed by 192 combined evidence phylogenetic and Bayesian biogeographic analysis. Zoological 193 Journal of the Linnaean Society . (doi:10.1111/zoj.12163). 194 [3] Deméré , T.A., Berta, A. & Adam, P.J. 2003 Pinnipedimorph evolutionary 195 biogeography. Bulletin of the American Museum of Natural History 279 , 32 76. 196 [4] Repenning, C.A. & Tedford, R.H. 1977 Otarioid seals of the Neogene. US 197 Geological Survey Professional Paper 992 , 1 87. 198 [5] Miyazaki, S., Horikawa, H., Kohno, N., Hirota, K., Kimura, M., Hasegawa, Y., 199 Tomida, Y., Barnes, L.G. & Ray, C.E. 1995 Summary of the fossil record of 200 pinnipeds of Japan, and comparisons with that from the eastern North Pacific. The 201 Island Arc , 361 372. 202 [6] Kohno, N., Koike, H. & Narita, K. 2007 Outline of fossil marine mammals from 203 the middle Miocene Bessho and Aoki Formations, Nagano Prefecture, Japan. 204 Research Reports of the Shinshushinmachi Fossil Museum 10 , 1 45. 205 [7] Barnes, L.G. 1989 A new enaliarctine pinniped from the Astoria Formation, 206 Oregon, and a classification of the Otariidae (Mammalia: Carnivora). Contributions in 207 Science, Natural History Museum of Los Angeles County 403 , 1 28. 208 [8] Kohno, N. 2004 Ecological shift in the otariid pinnipeds from pelagic to inshore: 209 evidence from the Middle Miocene record of the North Pacific. Journal of Vertebrate 210 Paleontology 24 , 79A. 211 [9] Berta, A. & Wyss, A.R. 1994 Pinniped phylogeny. Proceedings of the San Diego 212 Society of Natural History 29 , 33 56. 213 [10] Boessenecker, R.W. & Churchill, M. 2013 A reevaluation of the morphology, 214 paleoecology, and phylogenetic relationships of the enigmatic walrus Pelagiarctos . 215 PLoS ONE 8, e54311. 216 [11] Howard, H. & Barnes, L.G. 1987 Middle Miocene marine birds from the 217 foothills of the Santa Ana Mountains, Orange County, California. Natural History 218 Museum of Los Angeles County Contributions in Science 383 , 1 9. 219 [12] Turner, D.L. 1970 Potassium argon dating of Pacific Coast Miocene 220 foraminiferal stages. Geological Society of America Special Paper 124 , 91 129. 221 [13] Whistler, D.P. & Lander, E.B. 2003 New Late Uintan to Early Hemingfordian 222 land mammal assemblages from the Undifferentiated Sespe and Vaqueros Formations, 223 Orange County, and from the Sespe and equivalent marine formations in Los Angeles,
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224 Santa Barbara, and Ventura Counties, Southern California. Bulletin of the American 225 Museum of Natural History 279 , 231 268. 226 [14] Tedford, R.H., Albright, L.B., III,, Barnosky, A.D., Ferrusquia Villafranca, H., 227 R.M. Jr., Swisher, C.C., III,, Voorhies, M.R., Webb, S.D. & Whistler, D.P. 2004 228 Mammalian biochronology of the Arikareean through Hemphillian interval (Late 229 Oligocene through Early Pliocene epochs). In Late Cretaceous and Cenozoic 230 Mammals of North America: Biostratigraphy and Geochronology (ed. M.O. 231 Woodburne), pp. 169 231. New York, Columbia University Press. 232 [15] Barron, J.A. & Isaacs, C.M. 2001 Updated chronostratigraphic framework for the 233 California Miocene. In The Monterey Formation - from rocks to molecules (eds. C.M. 234 Isaacs & J. Rullkötter), pp. 393 395. New York, New York, Columbia University 235 Press. 236 [16] Kohno, N. 2006 A new Miocene odobenid (Mammalia: Carnivora) from 237 Hokkaido, Japan, and its implications for odobenid phylogeny. Journal of Vertebrate 238 Paleontology 26 , 411 421. 239 [17] Wiens, J.J. 1999 Polymorphism in systematics and conservation biology. Annual 240 Review of Ecology and Systematics 30 , 327 362. 241 [18] Goloboff, P.A., Farris, J.S. & Nixon, K.C. 2008 TNT, a free program for 242 phylogenetic analysis. Cladistics 24 , 774 786. 243 [19] Prothero, D.R., Bitboul, C.Z., Moore, G.W. & Moore, E.J. 2001 Magnetic 244 stratigraphy of the lower and middle Miocene Astoria Formation, Lincoln County, 245 Oregon. Pacific Section SEPM Special Publication 91 , 272 283. 246 [20] Berta, A. 1994 New specimens of the pinnipediform Pteronarctos from the 247 Miocene of Oregon. Smithsonian Contributions to Paleobiology 78 , 1 30. 248 [21] Hall, C.A. 2002 Nearshore marine paleoclimatic regions, increasing 249 zoogeographic provinciality, molluscan extinctions, and paleoshorelines, California: 250 Late Oligocene (27 Ma) to Late Pliocene (2.5 Ma). Geological Society of America 251 Special Paper 357 , 1 489. 252 253
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254 255 256 Figure 1 . Holotype specimen of Eotaria crypta , OCPC 5710 in ( a) medial view, ( b) 257 lateral view, and ( c) dorsal view. 258
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259 260 261 Figure 2 . Geochronologically calibrated cladogram depicting phylogenetic 262 relationships of Eotaria crypta . Support values include bootstrap support values 263 derived from non constraint analysis (left) and constraint analysis (right). Squares at 264 nodes denote position of enforced clades defined in constraint analysis. For 265 geochronologic ages of pinnipeds, see Supplementary Information.
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266 Electronic Supplementary Material for: 267 268 The oldest known fur seal 269 270 Robert W. Boessenecker and Morgan Churchill 271 272 ESM Contents: 273 274 Appendix 1. Measurements of the Eotaria crypta holotype (page 1) 275 Appendix 2. Character list for phylogenetic analysis (page 1) 276 Appendix 3. Character matrix for phylogenetic analysis (page 18) 277 Appendix 4. List of specimens included in phylogenetic analysis (page 20) 278 Appendix 5. Expanded description of cladistic methodology (page 23) 279 Appendix 6. Justification of geochronologic ranges for modern and fossil 280 pinnipeds (page 24) 281 282 Appendix 1. Measurements of the Eotaria crypta holotype (OCPC 5710) 283 284 Total length of mandible as preserved: 58.88 mm 285 Dorsoventral depth of mandible at P 2: 14.50 mm 286 Dorsoventral depth of mandible at P 3: 14.33 mm 287 Dorsoventral depth of mandible at P 4: 13.67 mm 288 Dorsoventral depth of mandible at M 1: 13.63 mm 289 Dorsoventral depth of mandible at M 2: 13.42 mm 290 Anteroposterior length/dorsoventral depth/transverse width of P 2: 5.59/5.63/3.44 mm 291 Anteroposterior length/dorsoventral depth/transverse width of P 3: 6.65/5.97/3.82 mm 292 Anteroposterior length/dorsoventral depth/transverse width of P 4: 6.73/5.72/3.70 mm 293 Anteroposterior length/dorsoventral depth/transverse width of M 1: 6.83/5.81/3.67 mm 294 Distance between P 2 3 crown apices, tip to tip: 6.92 mm 295 Distance between P 3 4 crown apices, tip to tip: 7.48 mm 296 Distance between P 4 M1 crown apices, tip to tip: 6.42 mm 297 P2 3 diastema: 0.90 mm 298 P3 4 diastema: 0.96 mm 299 P4 M1 diastema: 1.26 mm 300 301 Appendix 2. Character list for phylogenetic analysis 302 303 Character 1: Cranium: dorsoventral height. Modified from Churchill et al. ([1]: 304 character 1). 305 0: < 32% basal length of skull 306 1: > 32% or polymorphic for this trait 307 308 Character 2: Cranium: dorsal margin of skull at interorbital region. Modified 309 from Barnes et al. ([2]: character 31), Churchill et al. ([1]: character 2). 310 0: Flat 311 1: Slightly to strongly convex 312 313 Character 3: Cranium: widest portion of rostrum. Modified from Berta ([3]: 314 character 27), Barnes et al. ([2]: character 23), Churchill et al. ([1]: character 3). 315 0: Posterior to canines
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316 1: At canines, or rostrum same width throughout 317 318 Character 4: Cranium: facial angle. Modified from Berta and Deméré ([4]: 22), 319 Churchill et al. ([1]: character 4). 320 0: ≤ 65° 321 1: Polymorphic 322 2: > 65° 323 324 Character 5: Cranium: pseudosylvian sulcus on braincase. Modified from Berta 325 ([5]: character 17), Berta and Wyss ([6]: character 50), Kohno ([7]: character 20), 326 Kohno et al. ([8]: character 20), Kohno ([9]: character 28), Boessenecker and 327 Churchill ([10]: character 28), and Churchill et al. ([1]: character 95). 328 0: Present as a transverse furrow on lateral side of braincase 329 1: Absent 330 331 Character 6: Premaxilla: prenarial process. Modified from Berta ([5]: character 332 23), Berta ([11]: character 2), Berta and Wyss ([6]: character 3), Barnes et al. ([2]: 333 character 4), Kohno ([9]: character 1) and Boessenecker and Churchill ([10]: character 334 1), Churchill et al. ([1]: character 5). 335 0: Large, forming a half circle in dorsal view, and giving a tapered appearance to the 336 snout 337 1: Reduced to a low ridge in dorsal view, enhances overall bluntness of snout 338 2: Prenarial process absent or indistinct 339 340 Character 7: Premaxilla: depth of fossa between canine and incisor. Modified 341 from Bininda Emonds and Russell ([12]: character 20), Churchill et al. ([1]: character 342 6). 343 0: Shallow or absent 344 1: Polymorphic 345 2: Deep 346 347 Character 8: Premaxilla: fossa dorsal to canine. Modified from Kohno et al. ([8]: 348 character 14). 349 0: Absent 350 1: Present 351 352 Character 9: Premaxilla: contact with nasals. Modified from Wyss ([13]: character 353 15), Berta ([5]: character 38), Berta and Wyss ([6]: character 1), Deméré ([14]: 354 character 2), Deméré and Berta ([15]: character 1), Deméré and Berta ([16]: character 355 1), Barnes et al. ([2]: character 39), Kohno ([9]: character 3), Amson and Muizon 356 ([17]: character 11), Boessenecker and Churchill ([10]: character 3), Churchill et al. 357 ([1]: character 7). 358 0: Contact limited to the lateral margins of the anterior half of nasals 359 1: Contact between the premaxilla and nasal extends to midway along the lateral 360 margins of the nasal, or greater 361 2: Contact limited to anterior terminus of nasals with limited or no contact along the 362 lateral margins 363 364 Character 10: Premaxilla: lateral view. Modified from Berta and Deméré ([4]: 365 character 17), Churchill et al. [1]: character 8).
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366 0: Gradual slope from nasal region to prenarial region 367 1: Strongly concave 368 2: Premaxilla mostly excluded from lateral view 369 370 Character 11: Maxilla: fossa muscularis. Modified from Berta ([5]: character 32), 371 Berta ([11]: character 13), Berta and Wyss ([6]: character 8), Kohno ([7]: character 7), 372 Kohno ([9]: character 14), Boessenecker and Churchill ([10]: character 14), Churchill 373 et al. ([1]: character 9). 374 0: Present 375 1: Absent 376 377 Character 12: Maxilla: nasolabialis fossa. Modified from Berta and Deméré ([4]: 378 character 3), Berta ([5]: character 2), Berta ([11]: character 15), Berta and Wyss ([6]: 379 character 7), Kohno ([7]: character 12), Kohno et al. ([8]: character 12) Amson and 380 Muizon ([17]: character 22), Churchill et al. ([1]: character 10). 381 0: Present and well developed 382 1: Absent or poorly developed 383 384 Character 13: Maxilla: surface of posterodorsal portion. Modified from Koretsky 385 ([18]: character 12), Koretsky and Grigorescu ([19]: character 3), Koretsky and Holec 386 ([20]: character 12), Koretsky and Rahmat ([21]: character 3), Churchill et al. ([1]: 387 character 11). 388 0: Flat 389 1: Inflated 390 2: Inflated due to development of canines 391 392 Character 14: Maxillo-palatine suture: anterior edge. Modified from Bininda 393 Emonds and Russell ([12]: character 63), Churchill et al., ([1]: character 12). 394 0: Straight or M shaped 395 1: Polymorphic 396 2: Rounded 397 398 Character 15: Maxilla: diastema between upper P 4 and M 1. Modified from Barnes 399 et al. ([2]: character 26), Churchill et al. ([1]: character 13). 400 0: Absent 401 1: Present 402 2: Present and greatly elongated 403 404 Character 16: Maxilla: diastema between upper M 1 and M 2. Modified from Berta 405 and Deméré ([4]: character 21), Churchill et al. ([1]: character 14). 406 0: Absent 407 1: Polymorphic 408 2: Present 409 410 Character 17: Maxilla: Size of diastema between M 1 and M 2. Modified from Berta 411 and Deméré ([4]: character 21), Churchill et al. ([1]: character 15). 412 0: Slight diastema 413 1: Polymorphic 414 2: Large diastema 415
15
416 Character 18: Maxilla: visibility of infraorbital foramen in lateral view. Modified 417 from Berta and Wyss ([6]: character 11), Kohno ([9]: character 6), and Boessenecker 418 and Churchill ([10]: character 6), Churchill et al. ([1]: character 16). 419 0: Visible 420 1: Not visible 421 422 Character 19: Maxilla: embrasure pit between P 4 and M 1. Modified from Berta 423 ([5]: character 34), Berta ([11]: character 3), Berta and Wyss ([6]: character 14), 424 Churchill et al. ([1]: character 17). 425 0: Deep 426 1: Shallow or absent 427 428 Character 20: Maxilla: palatine process. Modified from Berta ([5]: character 1), 429 Berta ([3]: character 1), Deméré and Berta ([16]: character 3), Churchill et al. ([1]: 430 character 18). 431 0: Terminates at last molar 432 1: Extends past anterior margin of temporal fossa 433 2: Extends to approximate level of postorbital process of zygomatic 434 3: Extends past the level of the postorbital process of zygomatic 435 436 Character 21: Rostrum: nasal-frontal suture . Modified from Berta and Wyss ([6]: 437 character 4), Deméré ([14]: character 3, 4), Kohno ([7]: character 13), Kohno et al. 438 ([8]: character 9), Deméré and Berta ([15]: character 2), Deméré and Berta ([16]: 439 character 3), Kohno ([9]: character 4), Amson and Muizon ([17]: character 17), 440 Boessenecker and Churchill ([10]: character 4), Churchill et al. ([1]: character 19). 441 0: Transverse 442 1: V shaped 443 2: W shaped 444 445 Character 22: Nasals: anterior flaring. Modified from Berta and Deméré ([4]: 446 character 26), Barnes et al. ([2]: character 16), Churchill et al. ([1]: character 20). 447 0: Lateral walls parallel and largely straight, with minor anterior flaring 448 1: Lateral wall concave, with extreme flaring of the anterior portion of the nasals 449 2: Nasals V shaped, steadily widen anteriorly 450 451 Character 23: Nasals: extension of nasals into maxilla. Modified from Berta ([5]: 452 character 48), Berta ([3]: character 17), Berta and Wyss ([6]: character 5), Koretsky 453 ([18]: character 11), Koretsky and Holec ([20]: character 12), Amson and Muizon 454 ([17]: character 16). 455 0: Nasals extend to anterior margin of maxilla 456 1: Nasals penetrate far posteriorly between frontals 457 2: Nasals extend posteriorly past anterior margin of maxilla 458 459 Character 24: Palate: surface. Modified from Deméré ([14]: character 9), Kohno 460 ([7]: character 22), Kohno et al. ([8]: character 26), Deméré and Berta ([15]: character 461 6), Deméré and Berta ([16]: character 4), Barnes et al. ([2]: character 38), Kohno ([9]: 462 character 9), Boessenecker and Churchill ([10]: character 9), Churchill et al. ([1]: 463 character 21). 464 0: Flat to slightly concave 465 1: Polymorphic
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466 2: Deeply concave 467 468 Character 25: Palate: length. Modified from Barnes et al. ([2]: character 41), 469 Churchill et al. ([1]: character 22). 470 0: Long (53 60% BL) 471 1: Polymorphic 472 2: Short (45 52% BL) 473 3: Extremely Short (< 45% BL) 474 4: Extremely Long (> 60% BL) 475 476 Character 26: Palatine: shape of posterior edge. Modified from Churchill et al. ([1]: 477 character 23). 478 0: Arched or triangular 479 1: Polymorphic 480 2: Straight 481 482 Character 27: Pterygoid: hamular process shape. Modified from Berta ([3]: 483 character 10), Berta and Wyss ([6]: character 22), 484 0: Rounded with convex lateral margin 485 1: Flat with concave lateral margin 486 487 Character 28: Pterygoid: hamular process. Modified from Deméré ([14]: character 488 12), Barnes et al. ([2]: character 28), Kohno ([9]: character 12), Boessenecker and 489 Churchill ([10]: character 12), Churchill et al. ([1]: character 24). 490 0: Minor dorsoventral development 491 1: Enlarged, with extensive dorsoventral development 492 2: Absent 493 494 Character 29: Pterygoid: pterygoid strut. Modified from Berta and Wyss ([6]: 495 character 22), Deméré ([14]: character 13), Kohno ([7]: character 3), Kohno et al. ([8]: 496 character 5), Deméré and Berta ([15]: character 7), Barnes et al. ([2]: character 27), 497 Kohno ([9]: character 13), and Boessenecker and Churchill ([10]: character 13). 498 0: Transversely thin 499 1: Transversely thickened 500 501 Character 30: Orbit: anterior margin. Modified from Barnes et al. ([2]: character 502 6), Churchill et al. ([1]: character 25). 503 0: Indistinct ridge connecting antorbital process with zygomatic arch 504 1: Low ridge connecting antorbital process with zygomatic arch 505 2: Ridge developed into prominent anterior plate 506 507 Character 31: Orbit: antorbital process. Modified from Berta and Wyss ([6]: 508 character 16), Berta ([11]: character 14), Deméré ([14]: character 5), Kohno ([7]: 509 character 8), Kohno et al. ([8]: character 30), Deméré and Berta ([15]: character 4), 510 Barnes et al. ([2]: character 40), Amson and Muizon ([17]: character 19), Churchill et 511 al. ([1]: character 26). 512 0: Indistinct but present 513 1: Small ridge 514 2: Well developed 515
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516 Character 32: Orbit: construction of antorbital process. Modified from Deméré 517 ([14]: character 6), Kohno ([9]: character 15), Boessenecker and Churchill ([10]: 518 character 15), Churchill et al. ([1]: character 27). 519 0: From frontal and maxilla 520 1: From frontal only 521 2: From maxilla only 522 523 Character 33: Orbit: breadth of skull across antorbital processes. Modified from 524 Churchill et al. ([1]: character 28). 525 0: ≤ Breadth of rostrum 526 1: < Breadth of rostrum 527 528 Character 34: Rostrum: frontal-maxilla suture. Modified from Deméré ([14]: 529 character 4), Kohno ([7]: character 13), Kohno et al. ([8]: character 9), Deméré and 530 Berta ([15]: character 3), Churchill et al. ([1]: character 29). 531 0: V shaped 532 1: Straight, transverse 533 2: Divergent, often with expansion of the frontal into maxilla as a lobe 534 535 Character 35: Frontal: constriction between braincase and orbital region in 536 dorsal view. Modified from Wyss ([22]: character 34), Berta and Wyss ([6]: character 537 18), Kohno ([7]: character 23), Kohno et al. ([8]: character 29), Kohno ([9]: character 538 17), Amson and Muizon ([17]: character 27), Boessenecker and Churchill ([10]: 539 character 17), Churchill et al. ([1]: character 30). 540 0: Narrowest constriction between braincase and supraorbital processes 541 1: Narrowest constriction adjacent to anterior margin of braincase 542 2: Narrowest constriction between orbits and anterior to supraorbital process 543 544 Character 36: Frontal: shape of intertemporal margin. Modified from Barnes et al. 545 ([2]: character 24), Churchill et al. ([1]: character 31). 546 0: Concave 547 1: Straight 548 549 Character 37: Frontal: supraorbital process shape. Modified from Berta and 550 Deméré ([4]; character 2), Wyss ([13]: character 12), Berta ([5]: character 7), Berta 551 ([11]: character 7), Berta and Wyss ([6]: character 17), Deméré ([14]: character 7), 552 Kohno ([7]: character 11), Kohno et al. ([8]: character 15), Deméré and Berta ([15]: 553 character 5), Deméré and Berta ([16]: character 8), Barnes et al. ([2]: character 9, 17), 554 Kohno ([9]: character 16), Amson and Muizon ([17]: character 26), Boessenecker and 555 Churchill ([10]: character 16), Churchill et al. ([1]: character 32). 556 0: Supraorbital ridge 557 1: Completely absent 558 2: Large; lateral margins expanded, giving supraorbital process a more rectangular 559 shape 560 3: Polymorphic 561 4: Large and triangular 562 563 Character 38: Frontal: angle between supraorbital process and anterior orbital 564 margin. Modified from Churchill et al. ([1]: character 33). 565 0: > 60˚
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566 1: Polymorphic 567 2: ≤ 60˚ 568 569 Character 39: Frontal: anterior root of sagittal crest. Modified from Barnes et al. 570 ([2]: character 21), Churchill et al. ([1]: character 34). 571 0: Crest emerges from region of the supraorbital processes, either from one point or 572 slightly bifid 573 1: Anterior emergence of crest bifid, and preceded by prominent divergent crests that 574 originate on the posterior portion of the supraorbital processes 575 576 Character 40: Lacrimal: fusion. Modified from Wyss ([13]: character 8), Berta ([5]: 577 character 6), Berta ([11]: character 6), Berta and Wyss ([6]: character 10), Churchill et 578 al. ([1]: character 35). 579 0: Distinct, present 580 1: Indistinct, fuses early in ontogeny to maxilla and frontal 581 582 Character 41: Orbital vacuities: position. Modified from Wyss ([13]: character 28), 583 Berta ([5]: character 33), Berta and Wyss ([6]: character 12), Deméré ([14]: character 584 24), Kohno ([9]: character 20), Boessenecker and Churchill ([10]: character 20), 585 Churchill et al. ([1]: character 36). 586 0: Absent 587 1: Present and anteriorly positioned 588 2: Present and posteriorly positioned 589 590 Character 42: Orbital vacuities: Extent of bone reduction. Modified from Wyss 591 ([13]: character 28), Berta ([5]: character 33), Berta and Wyss ([6]: character 12), 592 Deméré ([14]: character 24), Kohno ([9]: character 20), Boessenecker and Churchill 593 ([10]: character 20), Churchill et al. ([1]: character 37). 594 0: Minor, small foramen or fissure 595 1: Major, large foramen or greatly widened suture 596 597 Character 43: Zygomatic arch: ventral view. Modified from Barnes et al. ([2]: 598 character 5), Churchill et al. ([1]: character 38). 599 0: Laterally bowed 600 1: Unbowed or slightly medially bowed 601 602 Character 44: Zygomatic arch: jugal-squamosal articulation . Modified from 603 Wyss ([13]: character 18), Berta ([5]: character 50), Berta ([3]: character 9), Berta and 604 Wyss ([6]: character 39), Deméré ([14]: character 20), Kohno ([7]: character 6), 605 Kohno et al. ([8]: character 23), Deméré and Berta ([15]: character 9), Deméré and 606 Berta ([16]: character 11), Barnes et al. ([2]: character 34), Amson and Muizon ([17]: 607 character 25), Churchill et al. ([1]: character 39). 608 0: Jugal and zygomatic splint like 609 1: Mortised 610 611 Character 45: Squamosal: zygomatic process. Modified from Kohno ([7]: character 612 6), Deméré and Berta ([15]: character 9), Kohno ([9]: character 19), Boessenecker and 613 Churchill ([10]: character 19). 614 0: Zygomatic process tapers at distal end 615 1: Zygomatic dorsoventrally thickens anteriorly
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616 617 Character 46: Squamosal: mastoid and postglenoid process contact. Modified 618 from Churchill et al. ([1]: character 40). 619 0: Separated 620 1: Polymorphic 621 2: Closely appressed 622 623 Character 47: Squamosal and Occipital: relationship of mastoid process with 624 paroccipital process. Modified from Berta ([3]: character 6, 39), Berta ([11]: 625 character 1), Berta and Wyss ([6]: character 24, 45), Deméré ([14]: character 17), 626 Deméré and Berta ([15]: character 8), Koretsky ([18]: character 3), Koretsky and 627 Holec ([20]: character 3), Barnes et al. ([2]: character 1), Kohno ([9]: character 34), 628 Boessenecker and Churchill ([10]: character 34), Churchill et al. ([1]: character 41). 629 0: Close to paroccipital process connected via low discontinuous ridge 630 1: Close to paroccipital process connected via high discontinuous ridge 631 2: Paroccipital process distant but connected by low ridge 632 3: Paroccipital separate, but close to mastoid 633 634 Character 48: Basioccipital: shape. Modified from Berta and Deméré ([4]: character 635 14), Wyss ([13]: character 13), Berta ([5]: character 44), Berta and Wyss ([6]: 636 character 42), Deméré ([14]: character 14), Kohno ([9]: character 30), Boessenecker 637 and Churchill ([10]: character 30), Churchill et al. ([1]: character 42). 638 0: Trapezoidal 639 1: Rectangular 640 641 Character 49: Basicranium: carotid canal. Modified from Berta and Wyss ([6]: 642 character 38), Kohno ([9]: character 24), Amson and Muizon ([17]: character 33), 643 Boessenecker and Churchill ([10]: character 24), Churchill et al. ([1]: character 43). 644 0: Broad, with no overlap by tympanic 645 1: Polymorphic 646 2: Tympanic bulla overlaps or partially overlaps the canal, excluding much of it from 647 view on the ventral surface 648 3: Enclosed by tympanic bulla 649 650 Character 50: Tympanic bulla: relationship with basioccipital. Modified from 651 Berta ([5]: character 41), Berta ([3]: character 8), Berta and Wyss ([6]: character 35). 652 0: Abuts basioccipital 653 1: Underlaps basioccipital 654 655 Character 51: Tympanic bulla: posterior projection. Modified from Berta and 656 Deméré ([4]: character 40), Barnes et al. ([2]: character 25), Churchill et al. ([1]: 657 character 44). 658 0: Absent or indistinct 659 1: Short 660 2: Long and well developed 661 662 Character 52: Tympanic bulla: angle between posterior and lateral margins. 663 Modified from Churchill et al. ([1]: character 45). 664 0: > 90˚ 665 1: ~ 90˚
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666 667 Character 53: Tympanic bulla: ventral surface. Modified from Wyss ([13]: 668 character 11), Berta ([5]: character 43), Berta ([3]: character 40), Berta and Wyss ([6]: 669 character 37), Deméré and Berta ([16]: character 10), Koretsky ([18]: character 1), 670 Koretsky and Holec ([20]: character 1), Amson and Muizon ([17]: character 32), 671 Churchill et al. ([1]: character 46). 672 0: Bulbous, ventral apex visible in lateral view below mastoid process 673 1: Bulbous, not visible in lateral view 674 2: Flat or concave, not visible in lateral view 675 3: Extremely bulbous and pachyosteosclerotic 676 677 Character 54: Tympanic bulla: medial edge. New character. 678 0: Transversely rounded 679 1: Flattened into blade like crest 680 681 Character 55: Tympanic bulla: complex ornamentation. Modified from Berta and 682 Deméré ([4]: character 23), Barnes et al. ([2]: character 2), Churchill et al. ([1]: 683 character 47). 684 0: Absent from ventral surface 685 1: Present on ventral surface 686 687 Character 56: Basicranium: internal acoustic meatus. Modified from Wyss ([13]: 688 character 16), Berta ([5]: character 40), Berta ([3]: character 7), Berta and Wyss ([6]: 689 character 26), Kohno ([9]: character 22), Boessenecker and Churchill ([10]: character 690 22). 691 0: Present and canals for vestibulocochlear and facial nerves closely adjacent 692 1: Present and canals for vestibulocochlear and facial nerves incipiently separated 693 2: Absent and canals for vestibulocochlear and facial nerves completely separated 694 695 Character 57: Basicranium: pit for tensor tympani in petrosal. Modified from 696 Wyss ([13]: character 7), Berta ([5]: character 35), Berta ([11]: character 16), Berta 697 and Wyss ([6]: character 30), Churchill et al. ([1]: character 48). 698 0: Present 699 1: Absent 700 701 Character 58: Frontal: anterolateral corner of braincase. Modified from Barnes et 702 al. ([2]: character 15), Churchill et al. ([1]: character 49). 703 0: Forms a right angle 704 1: Smoothly merges with orbital region 705 706 Character 59: Frontal: lateral protuberances. Modified from Churchill et al. ([1]: 707 character 50). 708 0: Absent 709 1: Polymorphic 710 2: Present 711 712 Character 60: Occipital: exposure in dorsal view. Modified from Deméré ([14]: 713 character 18), Barnes et al. ([2]: character 29) Kohno ([9]: character 32), 714 Boessenecker and Churchill ([10]: character 32), Churchill et al. ([1]: character 51). 715 0: Visible as a triangular wedge between nuchal crests
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716 1: Polymorphic 717 2: Not visible or only present as a very small triangular wedge in dorsal view 718 3: Visible as a rounded crescent 719 720 Character 61: Braincase: sagittal crest. Modified from Deméré ([14]: character 19), 721 Churchill et al. ([1]: character 52). 722 0: Present 723 1: Absent 724 2: Polymorphic 725 3: Separate temporal ridges present 726 727 Character 62: Braincase: shape of sagittal crest. Modified from Barnes et al. ([2]: 728 character 19), Churchill et al. ([1]: character 53). 729 0: Low ridge 730 1: Convex 731 2: Low, increases in height posteriorly 732 733 Character 63: Braincase: position of sagittal crest. Modified from Barnes et al. ([2]: 734 character 20), Churchill et al. ([1]: character 54). 735 0: Largely confined to braincase 736 1: Emergence of sagittal crest in orbital region, extending to braincase 737 738 Character 64: Braincase: shape of nuchal crest in lateral view. Modified from 739 Churchill et al. ([1]: character 55). 740 0: Project from dorsal surface of the back of the sagittal crest anteroventrally over the 741 top of the mastoid to the external auditory meatus 742 1: Curved: traces the posterior margin of the skull onto the mastoid process 743 2: Nuchal crests absent or indistinct, 744 745 Character 65: Mandible: shape of ventral margin. Modified from Deméré ([14]: 746 character 43), Kohno ([9]: character 40), Boessenecker and Churchill ([10]: character 747 45), Churchill et al. ([1]: character 56). 748 0: Straight 749 1: Polymorphic 750 2: Sinuous 751 752 Character 66: Mandible: genial tuberosity. Modified from Boessenecker and 753 Churchill ([10]: character 37), Churchill et al. ([1]: character 57). 754 0: Absent or weakly developed 755 1: Large genial tuberosity 756 757 Character 67: Mandible: development of digastric insertion. Modified from Berta 758 ([5]: character 51), Berta and Wyss ([6]: character 52), Deméré ([14]: character 44), 759 Deméré and Berta ([16]: character 22), Boessenecker and Churchill ([10]: character 760 46), Churchill et al. ([1]: character 58). 761 0: Absent or indistinct, mandible has a rounded ventral cross section 762 1: Anteroposteriorly present as a short, sharp crest 763 2: Posteroventrally expanded as elongate flange 764
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765 Character 68: Mandible: angular process shape. Modified from Berta and Deméré 766 ([4]: character 25), Berta ([3]: character 13), Berta and Wyss ([6]: character 51), 767 Deméré and Berta ([16]: character 21), Amson and Muizon ([17]: character 53), 768 Boessenecker and Churchill ([10]: character 49), Churchill et al. ([1]: character 59). 769 0: Narrow 770 1: Broad 771 2: Reduced to low triangular ridge or bump 772 3: Absent or indistinct 773 774 Character 69: Mandible: medial shelf of angular process. Modified from Berta 775 and Deméré ([4]: character 24), Boessenecker and Churchill ([10]: character 49), 776 Churchill et al. ([1]: character 60). 777 0: Does not form medial shelf 778 1: Forms small medial shelf 779 780 Character 70: Mandible: base of coronoid. Modified from Berta and Deméré ([4]: 781 character 16), Berta ([5]: character 45), Boessenecker and Churchill ([10]: character 782 50), Churchill et al. ([1]: character 61). 783 0: Narrow (< 42% of mandible length) 784 1: Polymorphic 785 2: Broad (≥ to 42% of mandible length) 786 787 Character 71: Mandible: dorsoventrally deepest part of mandible. Modified from 788 Koretsky ([18]: character 26), Koretsky and Grigorescu ([19]: character 14), 789 Boessenecker and Churchill ([10]: character 43), Koretsky and Rahmat ([21]: 790 character 14). 791 0: Near lower molars 792 1: At anterior end of mandible, at level of genial tuberosity 793 2: Polymorphic 794 3: Posterior to toothrow, at digastric insertion 795 796 Character 72: Mandible: position of genial tuberosity (or symphysis). Modified 797 from Koretsky ([18]: character 22), Koretsky and Grigorescu ([19]: character 10, 13?), 798 Boessenecker and Churchill ([10]: character 42), Koretsky and Rahmat ([21]: 799 character 10). 800 0: At level of P 2 or anterior 801 1: Polymorphic 802 2: Posterior to P 2 803 804 Character 73: Mandible: length of masseteric fossa. Modified from Churchill et al. 805 ([1]: character 62). 806 0: Long ( > 28% length of mandible) 807 1: Short (< 28% length of mandible) 808 809 Character 74: Dentition: postcanine crown shape. Modified from Berta and Wyss 810 ([6]: character 75), Berta ([3]: character 21), Boessenecker and Churchill ([10]: 811 character 63). 812 0: Transversely narrow and anteroposteriorly longer than high 813 1: Transversely narrow and equidimensional or anteroposteriorly shorter than high 814 2: Bulbous and anteroposteriorly longer than high
23
815 3: Bulbous and equidimensional or anteroposteriorly shorter than high 816 817 Character 75: Dentition: extension of upper tooth row. Modified from Churchill et 818 al. ([1]: character 63). 819 0: Extends to level of the maxillary base of the zygomatic arch 820 1: Extends to level of anterior portion of temporal fossa 821 2: Extends to or past level of middle of temporal fossa 822 3: Well anterior to the level of the maxillary base of the zygomatic arch 823 824 Character 76: Upper dentition: orientation of P 4 and M 1. New character. 825 0: long axes of P 4 and M 1 divergent, form angle 826 1: long axes of P 4 and M 1 parallel 827 828 Character 77: Upper dentition: heterodonty. Modified from Berta and Deméré ([4]: 829 character 4), Berta ([5]: character 19), Berta and Wyss ([6]: character 66). 830 0: P 4 largest, P 1 3 and M 1 2 similar in size 831 1: P 1 M1 similar in size 832 2: M 1 2 smaller relative to P 2 4 833 3: P 2 and P 3 larger than P 1 and P 4 M1 834 835 Character 78: Upper I 3: morphology. Modified from Berta ([5]: character 46), 836 Berta and Wyss ([6]: character 58), Koretsky ([18]: character 40), Koretsky and 837 Grigorescu ([19]: character 27), Koretsky and Holec ([20]: character 32), Barnes et al. 838 ([2]: character 13), Koretsky and Rahmat ([21]: character 27). 839 0: Small, incisiform, less than 150% diameter of I 2 840 1: Large, caniniform, and greater than 150% diameter of I 2 841 842 Character 79: Upper I 3: cross section. Modified from Berta and Deméré ([4]: 843 character 15), Berta ([5]: character 46), Berta and Wyss ([6]: character 58), Kohno 844 ([7]: character 21). 845 0: Circular 846 1: Oval. 847 848 Character 80: Upper I 3: cingulum. Modified from Berta and Deméré ([4]: character 849 5), Berta ([5]: character 47), Berta ([11]: character 20), Berta and Wyss ([6]: character 850 59), Kohno et al. ([8]: character 18). 851 0: Cingulum reduced or absent 852 1: Small lingual cusp on cingulum 853 854 Character 81: Upper dentition: postcanine tooth row. Modified from Berta and 855 Deméré ([4]: character 27), Wyss ([13]: character 17), Berta ([5]: character 49), Berta 856 ([3]: character 2), Berta and Wyss ([6]: character 13), Barnes et al. ([2]: character 7, 857 8), Kohno ([9]: character 10), Amson and Muizon ([17]: character 1), Boessenecker 858 and Churchill ([10]: 10), Churchill et al. ([1]: character 64). 859 0: Laterally concave 860 1: Straight and parallel 861 2: Laterally convex 862 3: Postcanine tooth row kinked at ~ P 3 863 4: straight and posteriorly divergent 864
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865 Character 82: Postcanines: labial cingulum. Modified from Berta ([5]: character 866 28), Berta and Wyss ([6]: character 67), Churchill et al. ([1]: character 65). 867 0: Absent 868 1: Polymorphic 869 2: Present 870 871 Character 83: Upper postcanines: rooting. Modified from Berta and Deméré ([4]: 872 character 19), Berta ([5]: character 26, 27), Berta ([3]: character 24), Berta ([11]: 873 character 8, 9), Berta and Wyss ([6]: character 62, 64, 65), Deméré ([14]: character 874 37), Kohno ([7]: character 15, 16), Kohno et al. ([8]: character 4), Deméré and Berta 875 ([15]: character 18), Deméré and Berta ([16]: character 25), Koretsky ([18]: character 876 33), Koretsky and Grigorescu ([19]: character 19), Koretsky and Holec ([20]: 877 character 23, 24), Barnes et al. ([2]: character 11), Amson and Muizon ([17]: 878 character 5), Boessenecker and Churchill ([10]: character 74, 76, 77), Koretsky and 879 Rahmat ([21]: character 19), Churchill et al. ([1]: character 67, 71, 74). 880 0: P 2 3 and M 1 double rooted, P 4 triple rooted 881 1: P 2 3 double rooted, P 4 M1 triple rooted 882 2: P 2 M1 double rooted 883 3: P 2 P3 single rooted, P 4 M1 double rooted 884 4: P 2 M1 single rooted 885 5: P 2 M1 single rooted 886 887 Character 84: Upper P 3-P4: crowns. Modified from Berta and Deméré ([4]: 888 character 20), Deméré ([14]: character 35), Koretsky ([18]: character 37), Koretsky 889 and Grigorescu ([19]: character 20, 24), Koretsky and Holec ([20]: character 25, 29), 890 Koretsky and Rahmat ([21]: character 20, 24), Churchill et al. ([1]: character 66). 891 0: Three cusps 892 1: Two cusps, paracone emphasized 893 2: One cusp 894 3: Peglike crown 895 4: Three cusps, paracone emphasized 896 897 Character 85: Upper P 2-3: posterolingual shelf. Modified from Kohno ([7]: 898 character 5), Kohno et al. ([8]: character 7), Deméré and Berta ([15]: character 14). 899 0: Absent 900 1: Present 901 902 Character 86: Upper P 4: protocone shelf. Modified from Berta and Deméré ([4]: 903 character 4), Berta ([5]: character 37), Berta ([3]: character 23), Berta ([11]: character 904 17), Berta and Wyss ([6]: character 63), Deméré ([14]: character 36), Deméré and 905 Berta ([15]: character 17), Deméré and Berta ([16]: character 30), Boessenecker and 906 Churchill ([10]: character 75), Churchill et al. ([1]: character 70). 907 0: Present 908 1: Absent 909 910 Character 87: Upper M 1. Modified from Berta and Deméré ([4]: character 41), 911 Churchill et al. ([1]: character 73). 912 0: Present 913 1: Absent 914
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915 Character 88: Upper M 2. Modified from Berta and Deméré ([4]: character 8), Berta 916 and Wyss ([6]: character 68), Deméré ([14]: character 33), Barnes et al. ([2]: character 917 35), Amson and Muizon ([17]: character 6), Churchill et al. ([1]: character 75). 918 0: Present 919 1: Polymorphic 920 2: Absent 921 922 Character 89: Upper M 2: rooting. Modified from Kohno ([7]: character 13), Kohno 923 et al. ([8]: character 13), Kohno ([9]: character 50), and Boessenecker and Churchill 924 ([10]: character 80) 925 0: Double 926 1: Single 927 928 Character 90: Lower dentition: tooth row length. Modified from Berta and 929 Deméré ([4]: character 18), Berta ([11]: character 10), Berta and Wyss ([6]: character 930 69), Koretsky ([18]: character 29?), Koretsky and Grigorescu ([19]: character 17?), 931 Boessenecker and Churchill ([10]: character 65), Koretsky and Rahmat ([21]: 932 character 17?), Churchill et al. ([1]: character 76). 933 0: Long (> 40% of length of mandible) 934 1: Polymorphic 935 2: Short (< 40% of length of mandible) 936 937 Character 91: Lower dentition: heterodonty. Modified from Berta and Deméré ([4]: 938 character 4). 939 0: M 1 anteroposteriorly longer than P 1 2 940 1: M 1 similar in anteroposterior length to P 1 2 941 942 Character 92: Lower postcanines: rooting. Modified from Berta and Deméré ([4]: 943 character 6, 7), Deméré and Berta ([15]: character 13), Koretsky and Grigorescu ([19]: 944 character 19), Boessenecker and Churchill ([10]: character 72, 73, 79), Churchill et al. 945 ([1]: character 79, 80). 946 0: Double 947 1: Polymorphic 948 2: Single 949 950 Character 93: Lower postcanines: paraconid and hypoconid. Modified from Berta 951 and Deméré ([4]: character 20), Berta ([5]: character 21, 52), Berta and Wyss ([6]: 952 character 70), Deméré and Berta ([15]: character 19, 20), Deméré and Berta ([16]: 953 character 27), Boessenecker and Churchill ([10]: character 66, 68). 954 0: Paraconid and hypoconid well developed, paraconid trenchant 955 1: Paraconid and hypoconid well developed and conical 956 2: Paraconid present and conical, hypoconid absent 957 3: Paraconid large and positioned apically, hypoconid reduced or absent 958 4: Paraconid absent, hypoconid present and conical 959 5: Paraconid and hypoconid reduced or absent 960 961 Character 94: Lower postcanines: protoconid and metaconid . Modified from 962 Berta ([5]: character 30), Berta ([3]: character 18), Berta and Wyss ([6]: character 72), 963 Boessenecker and Churchill ([10]: character 70), Churchill et al. ([1]: character 82). 964 0: Present, positioned apically close to protoconid
26
965 1: Present, positioned evenly between protoconid and hypoconid 966 2: Reduced or absent, posterior margin of protoconid is straight or convex 967 3: Reduced or absent, protoconid is lanceolate with concave posterior margin 968 969 Character 95: Lower P 1: crown size. Modified from Churchill et al. ([1]: character 970 77). 971 0: Smaller than crowns of P 2 4 972 1: Similar in size to P 2 4 973 974 Character 96: Lower P 1: root width. Modified from Churchill et al. ([1]: character 975 78). 976 0: Root or alveolus is same diameter as P 2 4 977 1: Root or alveolus smaller in diameter than P 2 4 978 979 Character 97: Lower M 1-2: trigonid and talonid. Modified from Berta ([5]: 980 character 29), Berta ([11]: character 18), Berta and Wyss ([6]: character 71), Churchill 981 et al. ([1]: character 81). 982 0: Present 983 1: Suppressed 984 985 Character 98: Lower M 2. Modified from Berta ([5]: character 31), Berta ([11]: 986 character 19), Berta and Wyss ([6]: character 73), Churchill et al. ([1]: character 83). 987 0: Present 988 1: Polymorphic 989 2: Absent 990 991 Character 99: Lower postcanines: lingual cingulum in taxa with double rooted 992 teeth. New character. 993 0: Dorsally arched 994 1: Polymorphic 995 2: Straight 996 997 Character 100: Vertebrae: neural foramen. Modified from Berta and Deméré ([4]: 998 character 12), Churchill et al. ([1]: character 84). 999 0: Proportionally same size as in terrestrial carnivores 1000 1: Enlarged 1001 1002 Character 101: Cervical vertebrae: size. Modified from Berta and Wyss ([6]: 1003 character 77), Churchill et al. ([1]: character 85). 1004 0: Larger than thoracic and lumbar, spinal canal less than one half diameter of 1005 centrum 1006 1: Smaller than thoracic and lumbar, with spinal canal nearly as large as centrum 1007 1008 Character 102: Lumbar vertebrae: transverse processes. Modified from Berta and 1009 Wyss ([6]: character 80), Churchill et al. ([1]: character 86). 1010 0: Long 1011 1: Short 1012 1013 Character 103: Scapula: secondary spine. Modified from Berta ([11]: character 12), 1014 Berta and Wyss ([6]: character 86), Churchill et al. ([1]: character 87).
27
1015 0: Absent 1016 1: Present 1017 1018 Character 104: Humerus: supinator ridge. Modified from Wyss ([22]: character 1019 37), Berta ([3]: character 31), Berta and Wyss ([6]: character 89), Amson and Muizon 1020 ([17]: character 65), Churchill et al. ([1]: character 88). 1021 0: Well developed 1022 1: Absent or poorly developed 1023 1024 Character 105: Radius: position of pronator teres process. Modified from Berta 1025 and Wyss ([6]: character 96), Churchill et al. ([1]: character 89). 1026 0: Positioned on the distal 60% of the radius 1027 1: Positioned on the proximal 40% of the radius 1028 1029 Character 106: Femur: fovea for teres femoris ligament. Modified from Berta ([3]: 1030 character 32), Berta and Wyss ([6]: character 115), Churchill et al. ([1]: character 90). 1031 0: Present and well developed 1032 1: Strongly reduced or absent 1033 1034 Character 107: Tibia and fibula: fusion . Modified from Berta and Deméré ([4]: 1035 character 13), Wyss ([22]: character 6), Berta and Wyss ([6]: character 122), 1036 Churchill et al. ([1]: character 91). 1037 0: Unfused 1038 1: Polymorphic 1039 2: Fused proximally 1040 1041 Character 108: Calcaneum: median process on calcaneal tuber. Modified from 1042 Berta and Wyss ([6]: character 125), Deméré ([14]: character 52), Deméré and Berta 1043 ([15]: character 22), Kohno ([9]: character 59), and Boessenecker and Churchill ([10]: 1044 character 89). 1045 0: Absent 1046 1: Present 1047 1048 Character 109: Calcaneum: secondary shelf of sustentaculum. Modified from 1049 Berta and Deméré ([4]: character 11), Berta and Wyss ([6]: character 123), Churchill 1050 et al. ([1]: character 92). 1051 0: Absent or developed as a thin groove 1052 1: Developed as narrow shelf 1053 2: Developed as wide shelf 1054 1055 Character 110: Metacarpal 1: pit or rugosity. Modified from Berta and Wyss ([6]: 1056 character 99), Deméré ([14]: character 49), Kohno ([9]: character 56), and 1057 Boessenecker and Churchill ([10]: 86). 1058 0: Absent 1059 1: Pit or rugosity present 1060 1061 Character 111: Baculum: apex. Modified from Berta and Deméré ([4]: character 29, 1062 30), Churchill et al. ([1]: character 93). 1063 0: Transversely narrow 1064 1: Transversely narrow, resembles a figure 8 in anterior view
28
1065 2: Broad with keels 1066 3: Broad with keels, with further expansion laterally 1067 1068 Character 112: Mane. Modified from Churchill et al. ([1]: character 98). 1069 0: Absent 1070 1: Present in males 1071 2: Present in males and exaggerated 1072 1073 Character 113: Dentition: pigmentation. Modified from Churchill et al. ([1]: 1074 character 99). 1075 0: Absent 1076 1: Present 1077 1078 Character 114: Coloration: contrast between nape and crown in males. Modified 1079 from Churchill et al. ([1]: character 104) 1080 0: Absent 1081 1: Present 1082 1083 Character 115: Body size. Modified from Churchill et al. ([1]: character 105). 1084 0: Small taxa (<300 kg) 1085 1: Large taxa (>300 kg) 1086 1087 Appendix 3. Character list for phylogenetic analysis. 1088 1089 Enaliarctos emlongi 1090 0000000000000000?00000000000000000000?0000000000000000000000000100000 1091 000100000000200000000000000000???????????????0 1092 1093 Pteronarctos goedertae 1094 0000000010000000?011(02)0002000000002110?10101000102000000000000001000 1095 00000000?111002000000100001?00000?10??????0????0 1096 1097 Proneotherium repenningi 1098 0010101110?0000??01200002000100102000?01111000100000101?0002000100001 1099 0100010111010101000101011?0?000?0???0010?????0 1100 1101 Neotherium mirum 1102 0010122000110000?01220000000100101101?01??1000100000200??102000101001 1103 0100011110?1011100010101100100?????0??101????0 1104 1105 Imagotaria downsi 1106 10101220?0110000?0120?00000010?101001?01??00001000002001?1020001110010 1107 110201110010211000101132?0112???0101?101????1 1108 1109 Pelagiarctos 1110 spp. ????????????????????????????????????????????????????????????????010???10 1111 ?2???????0?0??????103110100???????????????0 1112
29
1113 Odobenus rosmarus 1114 10101200221121???01300024202121111101??1210000110001200111132??0000100 1115 12123?1???20430112?0?2521012?1100101010100001 1116 1117 Monachus monachus 1118 100013000210000??01212101010000201001?0111111030310130021002000100210 1119 2100201310042240102?110110012011001012000?0000 1120 1121 Erignathus barbatus 1122 110013000211100??01112101210000201000??1101110303100300200031??200230 1123 1321001100040240102?110110012?11000012000?0001 1124 1125 Allodesmus kernensis 1126 0000130000?10?12?01210204?1?000201210?01??11102021002001?1000001212000 1127 321301210040420100101252?010?101011100000???1 1128 1129 Desmatophoca oregonensis 1130 0000120000?10002?01210200110000201010?010001002021002002?000000121200 1131 022031121004024000010101100111???01??????????1 1132 1133 Eotaria 1134 crypta _n.g._n.sp. ????????????????????????????????????????????????????????????? 1135 ???000???10?1???????0????????1013??102???????????????0 1136 1137 Pithanotaria 1138 starri ?010?00??0????1???11???0?0??0???1???4?0?11100?????????0??00?000?001? 1139 0?12?111111110220?02?0?053???20101100?0?0?????0 1140 1141 Thalassoleon mexicanus 1142 0010100001110200?1122000000001121210200111100010201010001000120100000 1143 2100111110110220100001053?0120001110100001???1 1144 1145 Thalassoleon 1146 macnallyae ?0??1?????????02??12???0?0??0????2114?0??????0110011211??000000 1147 0000010120111??10?02???00001053?0?220011101100?????0 1148 1149 Thalassoleon 1150 inouei ?????????????????????????0000????????????????0100011211?1???????010?1 1151 01201???????2???????01053?0122???????????????0 1152 1153 Proterozetes ulysses 1154 1100122000110022?012200020000112120040111110001?2010201?1102010000000 1155 0101111110?124????110125??1?2?1????1?????????1 1156 1157 Callorhinus 1158 gilmorei ?????0????????00??1????????????????14????????001????????????????0000 1159 0012011??????0320100021123?0122101110?1?2?????0 1160
30
1161 Callorhinus ursinus 1162 0002100001111000?1122100300000020211300111100011001121101000000000001 1163 01201011110104201010212231012?1011111002011110 1164 1165 Zalophus californianus 1166 101010201011000??1122000200001121200301111100011201120001102011000011 1167 0100101110012420102?212130012?1011111202021111 1168 1169 Eumetopias jubatus 1170 11012201011012??11221000000011212002111111000112010201011020100000002 1171 101111110010420102?012530112?1011111102031101 1172 1173 Otaria byronia 1174 101011101011010211132102420102121210211111100210202120101122020021111 1175 21001011100124201011212531012?1?11111202032101 1176 1177 Arctocephalus australis 1178 001010201111000110122100210001121211400111100010101110001000020100110 1179 01001111110314201000112130012?1011111202001100 1180 1181 1182 Appendix 4. List of specimens included in phylogenetic analysis 1183 1184 List of examined cranial and mandibular material. Abbreviations for specimens 1185 included within this study are as followed: AMNH , American Museum of Natural 1186 History, New York City, NY, USA; CAS , California Academy of Science, San 1187 Francisco, California, USA; CBM , Natural History Museum and Institute, Chiba, 1188 Japan; CM , Carnegie Museum of Natural History, Pittsburg, Pennsylvania, USA; 1189 HUNHM, Hokkaido University Natural History Museum, Sapporo, Japan; HUMZ , 1190 Laboratory of Marine Zoology, Hokkaido University, Hakodate, Japan ; HUTE , 1191 Geoscience Institute, Hyogo Prefecture, Japan; IGCU , Instituto de Geología, Ciudad 1192 Universitaria, Universidad Nacional Autónoma de México, Mexico City, Mexico; 1193 KUZ , Kyoto University Museum, Kyoto, Japan; LACM , Natural History Museum of 1194 Los Angeles County, Los Angeles, California, USA; NSMT , National Museum of 1195 Nature and Science, Tokyo, Japan; OCPC , John D. Cooper Archaeological and 1196 Paleontological Center, Fullerton, CA, USA ; PIN , Palaeontological Institute, Russian 1197 Academy of Sciences, Russia; SBMNH, Santa Barbara Museum of Natural History, 1198 Santa Barbara, California, USA; SCMNH , Santa Cruz Museum of Natural History, 1199 Santa Cruz, California, USA SDNHM , San Diego Natural History Museum, San 1200 Diego, California, USA; SFM , Shinshushinmachi Fossil Museum, Miyagi, Japan; 1201 UAM , University of Alaska, Fairbanks, AK, USA; UCMP , University of California 1202 Museum of Paleontology, Berkeley, California, USA; UOMNH , University of 1203 Oregon, Museum of Natural History, Eugene, Oregon, USA; USNM , National 1204 Museum of Natural History and Culture, Smithsonian Institution, Washington D.C., 1205 USA; UWBM , Burke Museum of Natural History, University of Washington, Seattle, 1206 Washington, USA. 1207 1208 Allodesmus kernensis (including A. kelloggi and A. gracilis ) 1209 LACM 4320, 21092, 138167,127939, SDNHM 116702, 54801 UCMP 81708, 194003, 1210 15184
31
1211 1212 Arctocephalus australis 1213 AMNH 254569, 254565, 205917, BMNH 1876 2 15 4, 1872 6 25 1, 1868 9 26 8, 1214 1968 9 26 2, 1968 9 26 4, 1950 11 14 1, 84 978, 84 972, 84 923, 84 921, 84 912, 1215 NSMT M 24898, USNM 396921, 550479, 550480, 396062, 23331, 504895, 239140 1216 1217 Callorhinus gilmorei 1218 SDNHM 25176, 25531, 26239, 25554, 25535 1219 1220 Callorhinus ursinus 1221 BMNH 1893 1 28 2, 1950 3 29 8, 1878 5 10 2, HUM 15111, 15198, 15026, 15911, 1222 15768, 15813, 15317, 15820, 15565, 15919, 15797, 15804, 15405, KUZ 15794, 1223 15788, 15784, 15782, 15780, 15779, 15768, 15766, 15762, 15759, 15758, 15755, 1224 UWBM 12550, 18335, 18336 1225 1226 Desmatophoca oregonensis 1227 LACM 123285, UOMNH F735 (cast), USNM 243694, 335430, 335457, 335478, 1228 335723, 314312, 123285, 3350702 1229 1230 Enaliarctos emlongi 1231 USNM 250345, 314540, 314290 1232 1233 Eotaria crypta 1234 OCPC 5710 1235 1236 Erignathus barbatus : AMNH 10135, CM 23304, 23305, 15316, 15312, 15311, 15313, 1237 23308, 15314, 23306, HUNHM 17205 48060, 48058, 58056, 47752, HUMZ A 0015, 1238 KUZ 1695, 1720, 1633, NSMT 24779, CA 165, 24777, USNM 188831, 188832, 1239 188834, UWBM 76856 1240 1241 Eumetopias jubatus 1242 BMNH 1992 272, 1950 3 29 11, 1950 7 21 4, KUZ 75K11, 75K10, 75K9, 75K8, 1243 75K6, 75K5, 75K4, 75K4, 75K3, 75K2, 75K1, UWBM 19896, 51177, 39483, 20152, 1244 51178, 32571, 6780 1245 1246 Imagotaria downsi 1247 SBMNH 342 (cast), UCMP 88459, USNM 83858, 184060 1248 1249 Monachus monachus : AMNH 73608, BMNH 1894 7 27 1, 1863 4 1 1, 1894 7 27 2, 1250 1951 4 17 1, USNM 219059 1251 1252 Neotherium mirum 1253 LACM 12300, 131950, UCMP 81665, 110618 1254 1255 Odobenus rosmarus 1256 AMNH 29903, 73303, 73302, CAS 261, CM 15337, UAM 11710, USNM 22014, 1257 21101, 7889, 21331, 218322 1258 1259 Otaria byronia
32
1260 AMNH 77910, 77920, 205919, 77918, 77917, 73120, BMNH WS 479, 1886 12 13 1, 1261 335 m, USNM 550142, 550307, 550227, 484912, 95063, 153568, 153567 1262 1263 Pelagiarctos sp. 1264 SDNHM 131041 1265 1266 Pelagiarctos thomasi 1267 LACM 121501, 123415, 38812, 7856, UCMP 93058 1268 1269 Pithanotaria starri 1270 USNM 11056, UCMP 219377 1271 1272 Proneotherium repenningi 1273 USNM 205333, 205334, 215068, 335526, 314628, 335697, 314541 1274 1275 Proterozetes ulysses 1276 USNM 187108, 187109, UCMP 219377 1277 1278 Pteronarctos goedertae 1279 LACM 123883, USNM 250320, 335432, 250323, 206274, 250282, 335695 1280 1281 Thalassoleon inouei 1282 NMNS PV 19656 (cast of CBMPV 807) 1283 1284 Thalassoleon macnallyae 1285 UCMP 219696, 219675, 219482, 219426, 112809, 128379, SCMNH 9975.1 1286 1287 Thalassoleon mexicanus 1288 NMNS PV 15411 (cast of IGCU 902), SDNHM 68313, 65172, 61563 1289 1290 Zalophus californianus 1291 BMNH 1966 10 24 2, 1968 6 10 1, CAS 23301, 22246, 22203, 22166, 22165, 1292 UWBM 34995, 315180, 32518, 27289, 34942, 34980, 34947, 39428, 34941, 34943 1293 1294 1295 Appendix 5. Expanded description of cladistic methodology 1296 1297 To determine the phylogenetic placement of Eotaria crypta , we performed a 1298 phylogenetic analysis of 115 morphological characters, including characters modified 1299 from Berta and Wyss [6], Kohno [9], Boessenecker and Churchill [10], and Churchill 1300 et al. [1]. We also included 3 novel characters. Character sampling was focused on 1301 those characters most useful for resolving the phylogenetic relationships of stem 1302 otariids and early pinnipeds. 1303 Twenty three pinnipeds were sampled, representing all families and all 1304 contemporary pinnipeds, including two early diverging pinnipedimorphs, two 1305 desmatophocids, two phocids, five odobenids, and twelve otariids (see 3. List of 1306 specimens included in phylogenetic analysis). Sampled otariids included all known 1307 fossil taxa described from the North Pacific, and five extant taxa. To minimize effects 1308 of extreme sexual dimorphism we used male individuals of extant Otariidae for 1309 coding. To accommodate substantial individual variation prevalent in pinnipeds [1],
33
1310 we used the polymorphic character coding method of Wiens [23], where taxa which 1311 possess two different states are coded for an intermediate “polymorphic” state and 1312 analyzed as an ordered character. 1313 Phylogenetic analyses were carried out in TnT [24]. Two separate analyses 1314 were performed; in the first analysis, no constraints on the topology were enforced. In 1315 the second analysis, the topology was constrained so that monophyly of Phocidae, 1316 Desmatophocidae, Odobenidae, and crown Otariidae was enforced. These are all 1317 strongly supported clades, whose monophyly is non controversial [1, 6 10, 14 17, 25, 1318 26]. We also enforced monophyly of an odobenid otariid clade, a result consistent 1319 with molecular analyses and some morphologic studies [25 27], but inconsistent with 1320 other studies [3, 6, 11]. Early diverging pinnipedimorphs, Desmatophocidae, Phocidae, 1321 Eotaria crypta , and fossil otariids were left as free floating in the constraint analysis. 1322 All analyses in TnT were implemented using 10,000 replicates with sectorial and tree 1323 fusing options checked. Bootstrap support values (BS) were calculated using 1324 symmetric resampling and 10,000 replicates. Alternative character weighting schemes 1325 were tested, including equal weighting and implied weighting, varying weights (K) 1326 from 2 6. The weighting scheme chosen for analysis was based on maximum 1327 resolution without significant decrease in bootstrap support values. 1328 1329 Appendix 6. Justification of geochronologic ranges for modern and fossil 1330 pinnipeds 1331 1332 The taxonomy of extant pinnipeds in this appendix follows that of the Society for 1333 Marine Mammalogy Committee on Taxonomy [28]. 1334 1335 Enaliarctos emlongi 1336 1337 Enaliarctos emlongi was originally reported by Berta [5] from early to middle 1338 Miocene rocks of the Newport Embayment along the Central Oregon coast. 1339 According to Berta [5], the holotype was collected from either the Astoria Formation 1340 or Nye Mudstone; Repenning ( in [5]) indicated the holotype specimen likely 1341 originated from the Nye Mudstone. The Nye Astoria contact at Jumpoff Joe (=type 1342 locality of Pteronarctos goedertae ) has been dated at 19.1 20.2 Ma based on 1343 paleomagnetism [29], and the Nye Mudstone is as old as 27 Ma [30]. Therefore, the 1344 geochronologic range of Enaliarctos emlongi is 19.1 27 Ma. 1345 1346 Pteronarctos goedertae 1347 1348 Pteronarctos goedertae was described by Barnes [27] from the basal Astoria 1349 Formation along the Central Oregon coast at Jumpoff Joe near Newport, Oregon. The 1350 Astoria Formation at Jumpoff Joe is 19.1 20.2 Ma in age based upon paleomagnetism 1351 [29]. Barnes [31] subsequently described a second species of Pteronarctos , 1352 Pteronarctos piersoni , from a horizon higher in the Astoria called the “Iron Mountain 1353 Bed” at Moloch Beach north of Newport, Oregon. According to paleomagnetic work 1354 by Prothero et al. [29], the “Iron Mountain Bed” of the Astoria Formation is 16.6 17.3 1355 Ma in age. A third enaliarctine from the Astoria Formation, Pacificotaria hadromma , 1356 was named from the “Iron Mountain Bed” by Barnes [32]; both Pteronarctos piersoni 1357 and Pacificotaria hadromma were considered junior synonyms of Pteronarctos 1358 goedertae by Berta [11], who concluded that both fell within the expected range of 1359 variation for a pinniped. Although Pacificotaria hadromma may possibly be distinct,
34
1360 we follow Berta [11] in recognition of Pteronarctos piersoni as a junior synonym of 1361 Pteronarctos goedertae . Since Pteronarctos goedertae occurs both at Jumpoff Joe 1362 and in the stratigraphically higher “Iron Mountain Bed”, this species ranges in age 1363 from 16.6 to 20.2 Ma. 1364 1365 Proneotherium repenningi 1366 1367 Proneotherium repenningi was named by Kohno et al. [8] from the “Iron 1368 Mountain Bed” in the Astoria Formation. Additional specimens were reported by 1369 Deméré and Berta [15], also from the “Iron Mountain Bed”. According to 1370 paleomagnetic analysis by Prothero et al. [29], the “Iron Mountain Bed” is 16.6 17.3 1371 Ma; this range constitutes the geochronologic range of Proneotherium . 1372 1373 Neotherium mirum 1374 1375 Neotherium was originally described by Kellogg [33] based on a few non 1376 associated postcranial elements. Subsequently a number of studies referred isolated 1377 bones to Neotherium , including a humerus [34], a radius [35], a partial mandible [36], 1378 and skulls [8, 15]. All known material of Neotherium mirum originates from the 1379 Sharktooth Hill Bonebed in the Round Mountain Silt Member of the Temblor 1380 Formation. The Sharktooth Hill Bonebed was concluded to reflect a 700 Ka period of 1381 deposition from 15.15 15.85 Ma based upon paleomagnetism and diatom 1382 biostratigraphy ([37] and references therein). 1383 1384 Pelagiarctos 1385 1386 Pelagiarctos thomasi was originally described by Barnes [36] from the 1387 Sharktooth Hill Bonebed in the Round Mountain Silt Member of the Temblor 1388 Formation, and all referred specimens of P. thomasi reported by Barnes [36] and 1389 Boessenecker and Churchill [10] were collected from the bonebed. Associated 1390 mandibles of Pelagiarctos sp. were reported by Boessenecker and Churchill [10] from 1391 the “Topanga” Formation in Orange County, approximately 17.5 15 Ma in age. The 1392 "Topanga" Formation has yielded land mammals which initially suggested correlation 1393 with the Barstovian NALMA [38, 39], but further work [40] has identified a more 1394 diverse land mammal assemblage indicative of early late Hemingfordian age; 1395 according to [41] the late Hemingfordian is approximately 15.9 17.5 Ma in age. 1396 Andesitic interbeds near the base of the Paulerino Member of the "Topanga" 1397 Formation further to the west in the San Joaquin Hills have yielded K/Ar dates of 15.8 1398 ± 1.3 Ma [40, 42]. Boessenecker and Churchill [10] summarized this evidence as 1399 suggesting an age of 15 17.5 Ma for the "Topanga" Formation in Orange County. 1400 However, a slightly more constrained age is possible based upon benthic foraminifera 1401 from the Relizian and early Luisian benthic foraminiferal zones [39] which 1402 correspond to an age of 14.9 17.1 Ma [43] for the “Topanga” Formation in Orange 1403 County. Because this age is greater than the minimum and maximum dates for the 1404 Sharktooth Hill Bonebed (15.15 15.85 Ma; [37] and references therein), 14.9 17.1 is 1405 given as the age for Pelagiarctos . 1406 1407 Imagotaria downsi 1408
35
1409 The holotype specimen of Imagotaria downsi was collected from the Great 1410 Lakes Carbon Co. Mine near Lompoc, California [44]; although Mitchell [44] 1411 considered the specimen to originate from the Sisquoc Formation and be late Miocene 1412 to early Pliocene in age, disagreement exists over whether these strata constitute the 1413 Monterey Formation or Sisquoc Formation. Unfortunately no biostratigraphic data 1414 from macroinvertebrates or microfossils appear to exist from the type locality [44] 1415 and searches of the geological literature yielded no additional information about this 1416 quarry. However, Repenning and Tedford [35] observed that similar diatomite occurs 1417 at a nearby quarry, Johns Manville Company quarry three miles north of Lompoc. At 1418 this quarry both the Monterey and stratigraphically higher Sisquoc Formation occur 1419 and are separated by an unconformity; Repenning and Tedford [35] further indicated 1420 that while previous studies had identified a Delmontian foraminiferal age (5.1 8.3 Ma, 1421 according to [43]) for these diatomites, more recent work by Barron [45] had 1422 indicated a Mohnian age (8.3 13.6 Ma, according to [43]) instead. Regardless, the 1423 existence of late middle and late Miocene diatomites of similar lithology in numerous 1424 quarries with poor stratigraphic control and the lack of robust age data for the 1425 holotype specimen makes any conclusion regarding the age of the type horizon 1426 speculative. 1427 Specimens referred by Mitchell [44] to Imagotaria downsi include a skull 1428 from the Celite Company No. 38 Quarry, 4.2 km southeast of Lompoc, California. 1429 This specimen subsequently yielded diatoms indicative of Schrader’s diatom zone XI 1430 (Barron, in [35]). Schrader’s diatom zone XI is roughly equivalent to the 1431 Thalassiosira antiqua concurrent range zone and Rhaponeis amphiceras var. elongata 1432 partial range zone of Barron [46], and corresponds to the Thalassiosira antiqua zone 1433 and lower part of the Nitzchia reinholdii subzone A of Barron and Isaacs [43]. The 1434 age of this specimen (and Schrader’s diatom zone XI) is approximately 7 8.5 Ma [43]. 1435 Other specimens questionably referred to Imagotaria downsi by Mitchell [44] 1436 include some associated postcrania (distal tibia, ribs) originally reported as ?otariid by 1437 Kellogg [47] from the Celite Company No. 9 quarry 2.4 km southeast of Lompoc, 1438 California. Diatomite mined at this locality is from the Monterey Formation and 8.2 1439 7.3 Ma in age [48]; however, given the tentative identification and the presence of 1440 other undescribed late Miocene “imagotariines” and dusignathines for which 1441 postcrania are unknown, this record is here treated as Odobenidae indeterminate. 1442 A partial articulated hindlimb originally described by Kellogg [47] from the 1443 Towsley Formation was referred to Imagotaria downsi by Repenning and Tedford 1444 [35]. Although considered to be approximately 9 12 Ma and identical in age with the 1445 Santa Margarita Sandstone by Repenning and Tedford [35] and Whitmore and Barnes 1446 [49], more recent work by Beyer et al. [50] yielded a Delmontian foraminiferal age, 1447 which can be summarized as 5.1 8.3 Ma in age [43]. However, a conference 1448 presentation suggested the Towsley Formation specimen may represent an early, as 1449 yet undescribed species of Gomphotaria [51]. Because of this possibility and the lack 1450 of craniodental material for this specimen, this record is not included here. 1451 A poorly preserved and crushed skull with associated teeth, mandible 1452 fragments, humerus, radius, tibia, and patella originally reported and referred to 1453 Pontolis magnus by Lyon [52] from the Valmonte Diatomite Member of the 1454 Monterey Formation in the Palos Verdes Hills was referred to Imagotaria downsi by 1455 Mitchell [44]. The Valmonte Diatomite is entirely of Mohnian foraminiferal age [53], 1456 corresponding to 7.1 13.5 Ma [43]. Mitchell ([44]:1879 1880) referred this specimen 1457 to Imagotaria downsi on the basis of sharing cuspate lingual cingula and incipiently 1458 double rooted postcanine teeth. However, this skull is substantially larger than the
36
1459 largest known skulls of Imagotaria downsi . It may possibly represent a 1460 geochronologically old record of an undescribed genus and species of gigantic 1461 dusignathine walrus known from a nearly complete skeleton from the Capistrano 1462 Formation of Orange County [54, 55]. This undescribed genus shares the 1463 aforementioned dental features of Imagotaria downsi identified by Mitchell [44]. 1464 Because of the ambiguity of the identification of this specimen, it is not considered 1465 further. 1466 Several well preserved skulls, mandibles, and postcrania were referred to 1467 Imagotaria downsi by Repenning and Tedford [35] from exposures of the upper sandy 1468 portions of the Santa Margarita Sandstone in Santa Cruz County. Invertebrates from 1469 the upper sandstones of the Santa Margarita Sandstone indicate correlation with the 1470 “Jacalitos” provincial megainvertebrate stage, and fossil equid teeth from the basal 1471 gravels indicate correlation with the Clarendonian North American Land Mammal 1472 Age (NALMA) which is dated at 9 12.5 Ma [41]. Repenning and Tedford [35] 1473 summarized the age of the Santa Margarita Sandstone in the southern Santa Cruz 1474 Mountains as 9 12 Ma in age, and summarized the age of Imagotaria downsi fossils 1475 from the upper sandstones as 9 10 Ma in age. The geochronologic range of 1476 Imagotaria downsi based upon robustly referred material can be summarized as 7 10 1477 Ma. 1478 1479 Odobenus 1480 1481 Fossils attributable to the modern walrus Odobenus are widely reported in 1482 Northern Hemisphere deposits of Pleistocene age (see summaries in [14, 56]). 1483 Although Pliocene specimens from the North Sea were originally identified as 1484 Odobenus huxleyi or Odobenus koninckii , these species and all known Pliocene 1485 odobenid material from the North Atlantic were reasonably interpreted as a single 1486 species by Kohno and Ray [56] who found that the oldest available name for this 1487 material was Ontocetus emmonsi . Although fossils assigned to the extant species 1488 Odobenus rosmarus are generally restricted to the Pleistocene [57], 1489 geochronologically older fossils from the Pliocene of Japan have been reported, 1490 including a well preserved cranium dredged from the Sea of Okhotsk off Sakhalin 1491 Island [58] and dated as 2 Ma in age [57, 58]. According to Miyazaki et al. [58], 1492 adhering matrix yielded diatoms corresponding to the Denticulopsis seminae var. 1493 fossilis Zone (1.89 2.5 Ma, [59]) and the Neodenticula koizumii Zone (1.7 2.4 Ma; 1494 [60]; 2.0 2.7 Ma according to [61]). A relatively straight tusk reported as Odobenus sp. 1495 by [62] was associated with diatoms assignable to the Neodenticula koizumii zone 1496 (2.0 2.7 Ma, [61]). Thus, the maximum age of fossil Odobenus is 2.7 Ma, late 1497 Pliocene, and the geochronologic range is given as 2.7 Ma to Recent. 1498 1499 Erignathus barbatus 1500 1501 Fossils of the extant bearded seal have been reported from several late 1502 Pleistocene Arctic localities and high latitude late Pleistocene localities in the North 1503 Pacific and North Atlantic [63 65] and as far south as South Carolina [66]. The oldest 1504 recorded fossil of Erignathus is a humerus and radius from the Weybourne Crag or 1505 Cromer Forest Bed Formation of early to middle Pleistocene age [64]. The 1506 geochronologic range of Erignathus is given as 1.81 Ma to Recent. 1507 1508 Monachus
37
1509 1510 Fossils of extant monk seals ( Monachus monachus ) are primarily late 1511 Pleistocene in age [66]. The oldest record of the genus Monachus are fossils of 1512 Monachus tropicalis from the early Pleistocene Bermont Formation at the Leisey 1513 Shell Pit in Florida [67]; this unit is 1.5 1.1 Ma in age, and vertebrate bearing parts of 1514 the formation are 1.3 Ma and younger [68]. The geochronologic range of Monachus is 1515 given as 1.3 Ma to Recent. 1516 1517 1518 Desmatophoca oregonensis 1519 1520 Fossils of Desmatophoca oregonensis have been reported from the Astoria 1521 Formation near Newport along the central Oregon coast. The holotype specimen was 1522 reported from the base of the Astoria Formation [69], while additional specimens 1523 referred to this species by Barnes [70] and Deméré and Berta [16] were collected from 1524 the stratigraphically higher “Iron Mountain Bed”. Because of this stratigraphic 1525 separation, these younger specimens were provisionally hypothesized to represent a 1526 separate species of Desmatophoca by Barnes [69]; however, in the absence of 1527 morphological evidence we follow Barnes [70] and Deméré and Berta [16] in 1528 identifying these specimens as D. oregonensis . As outlined about, the base of the 1529 Astoria Formation is approximately 19.1 20.2 Ma in age and the “Iron Mountain Bed” 1530 is approximately 16.6 17.5 Ma based upon paleomagnetism [29]. The geochronologic 1531 range is given as 16.6 20.2 Ma. 1532 1533 Allodesmus kernensis 1534 1535 The type specimen of Allodesmus kernensis was reported by Kellogg [71] 1536 from the Round Mountain Silt Member of the Temblor Formation near Bakersfield, 1537 California. Although assumed by some to originate from the highly fossiliferous 1538 Sharktooth Hill Bonebed, Mitchell [72] speculated (based upon Kellogg’s locality 1539 data and supposed plesiomorphic morphological features) that the holotype may have 1540 originated further down section in the Round Mountain Silt Member and 1541 stratigraphically below the bonebed, and referred all material from the Sharktooth Hill 1542 Bonebed to a separate species, Allodesmus kelloggi . However, Barnes [73] noted that 1543 conflicting locality information for the Allodesmus kernensis holotype exists and 1544 precludes assumptions about its stratigraphic position; he additionally referred all 1545 specimens from the Sharktooth Hill Bonebed to A. kernensis , which was followed by 1546 Deméré and Berta [16] and we follow that decision here. A third species from the 1547 Round Mountain Silt, Allodesmus gracilis , was erected by Barnes and Hirota [74] to 1548 contain all Allodesmus specimens aside from the A. kernensis and A. kelloggi 1549 holotypes; Deméré and Berta [16] also synonymized A. gracilis with A. kernensis , 1550 which is also followed here. Because the age of the Sharktooth Hill Bonebed is 15.15 1551 15.85, this is given as the geochronologic range of Allodesmus kernensis . 1552 1553 Eotaria crypta – OCPC 1710 1554 1555 The isolated partial mandible described herein was collected from the 1556 “Topanga” Formation in Mission Viejo, Orange County, California. Although 1557 collected from a separate locality than Pelagiarctos sp. reported by Boessenecker and 1558 Churchill [10], no geochronologic control finer than formation level age exists for the
38
1559 “Topanga” Formation in Orange County. However, (see Pelagiarctos ), the age of the 1560 "Topanga" Formation is regarded as early middle Miocene based upon land mammal 1561 correlations, biostratigraphy, and radiometric dates from andesitic interbeds [10, 39, 1562 40, 53]. Benthic foraminifera provide the finest age control possible and indicate the 1563 “Topanga” Formation is of Relizian and early Luisian age [39], corresponding to an 1564 age of 14.9 17.1 Ma [43]. 1565 1566 Pithanotaria starri 1567 1568 The holotype specimen of Pithanotaria starri , an impression of an articulated 1569 skeleton in a diatomite slab, was described by Kellogg [47] from the Monterey 1570 Formation near Lompoc in Santa Barbara County, California. The holotype specimen 1571 was collected from the Celite Company No. 9 quarry 2.4 km southeast of Lompoc, 1572 California. As discussed above (see entry for Imagotaria downsi ), diatomite from this 1573 quarry has yielded diatoms indicative of the Thalassiosira antiqua and Nitzschia 1574 reinholdii Zones, indicating the Monterey Formation within the quarry spans 8.2 7.3 1575 Ma [48]. Kellogg [47] referred additional specimens of Pithanotaria starri from the 1576 Celite Company # 5 and #15 quarries, but no published age determinations are 1577 available for these quarries. 1578 Referred specimens of Pithanotaria starri were reported by Repenning and 1579 Tedford [35] from the Santa Margarita Sandstone in the central Santa Cruz Mountains 1580 in Santa Cruz County and from northern Monterey County. Although the age of the 1581 latter locality is poorly constrained, the former locality was estimated at 9 10 Ma by 1582 Repenning and Tedford ([35]; see the entry for Imagotaria downsi above).The 1583 geochronologic range of Pithanotaria starri is given as 7.3 10 Ma. 1584 1585 Thalassoleon macnallyae 1586 1587 All known fossils of Thalassoleon macnallyae have been reported from 1588 exposures of the Purisima Formation in Northern and Central California [35]. The 1589 holotype specimen was collected from siltstone beds of the Purisima Formation at 1590 Point Reyes ([75]; formerly mapped as the upper member of the Drakes Bay 1591 Formation of [76]). The holotype specimen was collected from a horizon 1592 stratigraphically higher than a diatom flora correlative with subzone B of the North 1593 Pacific Diatom Zone X (Barron, in [75]). Subzone B of Diatom Zone X corresponds 1594 to Subzone B of the Nitzschia reinholdii Zone in the updated zonation in [45], which 1595 is approximately 6.4 5.6 Ma in age [43]. Although an age determination constraining 1596 an upper age limit based on microfossils, paleomagnetism, or absolute dating is not 1597 available, fossil teeth of Carcharodon hubbelli occur stratigraphically higher than 1598 strata exposed at the type locality of Thalassoleon macnallyae . In the Santa Cruz and 1599 San Gregorio sections of the Purisima Formation, teeth of Carcharodon hubbelli are 1600 present only in strata older than 5.33 5.6 Ma in age (based upon paleomagnetism and 1601 diatoms, respectively). This suggests an upper age limit of 5.33 Ma for the holotype 1602 specimen of Thalassoleon macnallyae . 1603 Additional specimens of Thalassoleon macnallyae were reported from the 1604 lower part of the Purisima Formation exposed near Santa Cruz, California [35]. These 1605 specimens, and others currently under study by the authors, are bracketed below by a 1606 6.9 ± 0.5 Ma K/Ar date from glauconite from the basal bonebed of the Purisima 1607 Formation [77]and above by a paleomagnetic reversal and diatom flora identifying the 1608 Mio Pliocene boundary at the horizon corresponding to the “Crab Marker Bed” of
39
1609 Madrid et al. [78], otherwise known as UCMP locality V 6875 and Bonebed 4 [79]. 1610 In total, the geochronologic range of Thalassoleon macnallyae can be summarized as 1611 6.9 5.33 Ma. 1612 1613 Thalassoleon mexicanus 1614 1615 Fossils of Thalassoleon mexicanus were originally reported by Repenning and 1616 Tedford [35] from the late Miocene Almejas Formation of Isla Cedros in Baja 1617 California. Estimates of the age of the vertebrate bearing beds of the Almejas 1618 Formation suggest these lower strata are approximately 6 8 Ma in age [80]. A more 1619 refined younger limit for this assemblage is provided by K/Ar dates from basalts that 1620 occur stratigraphically higher than the Almejas Formation on the Vizcaino Peninsula 1621 at Cerro de Elefante (6.48 ± 0.23 Ma) and Mesa de las Auras (5.7 ± 0.2 Ma), reported 1622 by Sawlan and Smith [81]. Although these dates are from basalts on the Vizcaino 1623 Peninsula on the mainland and not Isla Cedros, they corroborate the age estimation by 1624 Barnes [80] and this occurrence can be summarized as 5.7 8 Ma in age. 1625 Additional specimens were referred to Thalassoleon mexicanus by Deméré 1626 and Berta [82] from the upper siltstone member of the Capistrano Formation. Diatom 1627 floras from below and above the vertebrate bearing strata that produced these 1628 specimens of Thalassoleon mexicanus are correlative with subzone B of the Nitzschia 1629 reinholdii Zone and lower part of the Thalassiosira oestruppi Zone, corresponding to 1630 6.4 4.9 Ma [82]. Altogether, these age data indicate a geochronologic range of 4.9 8 1631 Ma for Thalassoleon mexicanus . 1632 1633 Thalassoleon inouei 1634 1635 Thalassoleon inouei was reported by Kohno [83] from the Mio Pliocene 1636 Senhata Formation of Japan. Although few age determinations for the Senhata 1637 Formation exist, Kohno [83] noted that Kanie et al. [84] had correlated the Senhata 1638 Formation with calcareous nannofossil zone CN 10B; zone CN 10B corresponds to 5 1639 5.3 Ma [43]. However, the occurrence of both Carcharodon hastalis and 1640 Carcharodon hubbelli [85, 86] suggest that the Senhata Formation is older than 7 8 1641 Ma, following age determinations for these species from Ehret et al. [87]. Kohno [83] 1642 concluded that the Senhata Formation was latest Miocene to early Pliocene, and 1643 following age boundaries for the Messinian and Zanclean stages of international 1644 usage, the geochronologic range of Thalassoleon inouei is conservatively summarized 1645 as 7.25 3.6 Ma. 1646 1647 Callorhinus gilmorei 1648 1649 This species was originally described from the Pliocene San Diego Formation 1650 by Berta and Deméré [4]. The San Diego Formation was traditionally considered Late 1651 Pliocene in age, approximately 2 3 Ma (e.g. [88] and references therein). However, 1652 more recent biostratigraphic and paleomagnetic research indicates the basal San 1653 Diego Formation is Early Pliocene in age and as old as 4 4.2 Ma, and that the upper 1654 parts ranges up to the Plio Pleistocene boundary [89, 90]; records of Callorhinus 1655 gilmorei from the San Diego Formation can be summarized as 1.8 4.2 Ma. 1656 Additional fossils of Callorhinus gilmorei were reported by Kohno and 1657 Yanagisawa [91] and Boessenecker [92] from Japan and Northern California. The 1658 Japanese specimen of Callorhinus gilmorei was collected from the Dainenji
40
1659 Formation, and based upon associated diatoms is 2.4 2.7 Ma in age [91]. The 1660 occurrence of Callorhinus gilmorei from the Rio Dell Formation of Northern 1661 California is constrained to 2.0 3.0 Ma based upon ash dates [92]. The 1662 geochronologic range of Callorhinus gilmorei may be summarized as 2 4.2 Ma. 1663 1664 Callorhinus ursinus 1665 1666 Although fossils of Callorhinus sp. have been reported from Pliocene and 1667 Pleistocene strata from around the North Pacific rim ([92]; also see references therein), 1668 comparatively little material has been referred to Callorhinus ursinus . Most records 1669 are simple reports without morphological description and may often reflect material 1670 perhaps better identified as Callorhinus sp., but such evaluation is beyond the purpose 1671 of this review and the original identifications are followed here. Fossils identified as 1672 Callorhinus ursinus include teeth and postcrania figured by Hasegawa et al. [93] from 1673 the late Pleistocene Shiriya Local Fauna in Japan and teeth and postcrania from the 1674 early Pleistocene Kanzawa Formation of Japan [94]. In the absence of intrinsic 1675 biochronologic or absolute dates for these occurrences, the beginning of the Early 1676 Pleistocene (1.81 Ma) is given as the maximum age for Callorhinus ursinus , and the 1677 geochronologic range is summarized as 1.81 Ma to Recent. 1678 1679 Arctocephalus 1680 1681 Few genuine fossil occurrences of southern fur seals exist. Many older records 1682 are now attributed to other genera. An example from California includes 1683 Arctocephalus sp. from the Mio Pliocene San Mateo Formation, originally identified 1684 by Domning ([95]:158), was reidentified as Thalassoleon by Deméré et al. [96] and 1685 likely even represent Thalassoleon mexicanus (Boessenecker, pers. obs.). The fur seal 1686 Hydrarctos lomasiensis was initially described as a subgenus of Arctocephalus by 1687 Muizon [97] but elevated to genus level by Berta and Deméré [4]. Arctocephalus 1688 caninus from the late Pliocene of New Zealand [98] is actually a Holocene specimen 1689 of Phocarctos hookeri [99, 100]. Abundant Pleistocene records of Arctocephalus have 1690 been reported from South Africa [101] and a single record exists from the late 1691 Pleistocene of Brazil [102]. The oldest record of Arctocephalus is a femur from the 1692 Early Pliocene (5 2.7 Ma) Duynefontyn Member of the Varswater Formation. The 1693 geochronologic range of Arctocephalus may be summarized as 5 Ma to Recent. 1694 1695 Zalophus 1696 1697 Few fossils of Zalophus have been described and all are Pleistocene in age, 1698 and restricted to Japan, California, and Baja California [57, 103]. The oldest fossils of 1699 Zalophus known from craniomandibular material are from the Middle Pleistocene of 1700 Japan [2, 57]. The geochronologic record of Zalophus can be summarized as 781 Ka 1701 to Recent. 1702 1703 Eumetopias 1704 1705 The fossil record of Eumetopias has recently been summarized by Barnes et al. 1706 [2] and Ray [104]. Many fragmentary specimens that may not be distinguishable from 1707 Proterozetes have been reported from the Pliocene of Japan [57]; regardless, 1708 Proterozetes may be a junior synonym of Eumetopias [92]. The oldest specimens of
41
1709 Eumetopias represented by craniodental or mandibular remains are from Early 1710 Pleistocene deposits in Japan [57, 105, 106]. The geochronologic range of Eumetopias 1711 may be summarized as 1.81 Ma to Recent. 1712 1713 Proterozetes ulysses 1714 1715 Proterozetes ulysses was described by Barnes et al. [2] from the Port Orford 1716 Formation along the southwestern Oregon coast. Although considered to be late 1717 Pliocene by Barnes et al. [2] based upon outdated studies by Baldwin [107], more 1718 recent amino acid racemization dates indicate the Port Orford Formation is Middle 1719 Pleistocene and 500 700 Ka in age [108]. Similarly, invertebrate biochronology based 1720 upon mollusks and echinoderms also indicate a Middle Pleistocene age [109]. The 1721 geochronologic range of Proterozetes ulysses may be summarized as 0.5 0.7 Ma. 1722 1723 Otaria 1724 1725 Fossils of the extant South American sea lion Otaria byronia have been 1726 reported from the Late Pleistocene of Estratos de Caldera of Chile [110] as well as the 1727 Late Pleistocene Chuí Formation of Brazil [111]. Fossils from the Estratos de Caldera 1728 are 105 ± 5 Ka in age [110]. No dates are available for the Chuí Formation, so dates 1729 for the Late Pleistocene (126 11 Ka) are used instead. In summary, the 1730 geochronologic range of Otaria byronia is 0.126 Ma to Recent. 1731 1732 References 1733 1734 [1] Churchill, M., Boessenecker, R.W. & Clementz, M.T. 2014 Colonization of the 1735 Southern Hemisphere by fur seals and sea lions (Carnivora: Otariidae), revealed by 1736 combined evidence phylogenetic and Bayesian biogeographic analysis. Zoological 1737 Journal of the Linnaean Society 172 , 200 225. 1738 [2] Barnes, L.G., Ray, C.E. & Koretsky, I.A. 2006 A new Pliocene sea lion, 1739 Proterozetes ulysses (Mammalia: Otariidae) from Oregon, U.S.A. In Mesozoic and 1740 Cenozoic Vertebrates and Paleoenvironments: Tributes to the Career of Prof. Dan 1741 Grigorescu (ed. Z. Csiiki), pp. 57 77. Bucharest, Romania. 1742 [3] Berta, A. 1994 A new species of phocoid pinniped Pinnarctidion from the early 1743 Miocene of Oregon. Journal of Vertebrate Paleontology 14 , 405 413. 1744 [4] Berta, A. & Deméré, T.A. 1986 Callorhinus gilmorei n. sp., (Carnivora: Otariidae) 1745 from the San Diego Formation (Blancan) and its implications for otariid phylogeny. 1746 Transactions of the San Diego Society of Natural History 21 , 111 126. 1747 [5] Berta, A. 1991 New Enaliarctos * (Pinnipedimorpha) from the Oligocene and 1748 Miocene of Oregon and the role of "Enaliarctids" in Pinniped phylogeny. . 1749 Smithsonian Contributions to Paleobiology 69 , 1 33. 1750 [6] Berta, A. & Wyss, A.R. 1994 Pinniped phylogeny. Proceedings of the San Diego 1751 Society of Natural History 29 , 33 56. 1752 [7] Kohno, N. 1994 A new Miocene pinniped in the genus Prototaria (Carnivora: 1753 Odobenidae) from the Moniwa Formation, Miyagi, Japan. Journal of Vertebrate 1754 Paleontology 14 , 414 426. 1755 [8] Kohno, N., Barnes, L.G. & Hirota, K. 1995 Miocene fossil pinnipeds of the genera 1756 Prototaria and Neotherium (Carnivora; Otariidae; Imagotariinae) in the North Pacific 1757 Ocean: Evolution, relationships and distribution. The Island Arc 3, 285 308.
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1758 [9] Kohno, N. 2006 A new Miocene odobenid (Mammalia: Carnivora) from 1759 Hokkaido, Japan, and its implications for odobenid phylogeny. Journal of Vertebrate 1760 Paleontology 26 , 411 421. 1761 [10] Boessenecker, R.W. & Churchill, M. 2013 A reevaluation of the morphology, 1762 paleoecology, and phylogenetic relationships of the enigmatic walrus Pelagiarctos . 1763 PLoS ONE 8, e54311. 1764 [11] Berta, A. 1994 New specimens of the pinnipediform Pteronarctos from the 1765 Miocene of Oregon. Smithsonian Contributions to Paleobiology 78 , 1 30. 1766 [12] Bininda Emonds, O.R.P. & Russell, A.P. 1996 A morphological perspective on 1767 the phylogenetic relationships of the extant phocid seals (Mammalia: Carnivora: 1768 Phocidae). Bonner Zoologische Monographien 41 , 1 256. 1769 [13] Wyss, A.R. 1987 The walrus auditory region and the monophyly of pinnipeds. 1770 American Museum Novitates 2871 , 1 31. 1771 [14] Deméré , T.A. 1994 The family Odobenidae: a phylogenetic analysis of fossil 1772 and living taxa. Proceedings of the San Diego Society of Natural History 29 , 99 123. 1773 [15] Deméré, T.A. & Berta, A. 2001 A reevaluation of Proneotherium repenningi 1774 from the Miocene Astoria Formation of Oregon and its position as a basal odobenid 1775 (Pinnipedia: Mammalia). Journal of Vertebrate Paleontology 21 , 279 310. 1776 [16] Deméré, T.A. & Berta, A. 2002 The Miocene pinniped Desmatophoca 1777 oregonensis Condon, 1906 (Mammalia: Carnivora) from the Astoria Formation, 1778 Oregon. Smithsonian Contributions to Paleobiology , 113 147. 1779 [17] Amson, E. & Muizon, C.d. 2013 A new durophagous phocid (Mammalia: 1780 Carnivora) from the late Neogene of Peru and consideration on monachine seals 1781 phylogeny. Journal of Systematic Palaeontology 12 , 523 548. 1782 [18] Koretsky, I.A. 2001 Morphology and systematics of Miocene Phocinae 1783 (Mammalia: Carnivora) from Paratethys and the North Atlantic region. Geologica 1784 Hungarica Series Palaeontologica 54 , 1 109. 1785 [19] Koretsky, I.A. & Grigorescu, D. 2002 The fossil monk seal Pontophoca 1786 sarmatica (Alekseev)(Mammalia: Phocidae: Monachinae) from the Miocene of 1787 Eastern Europe. Smithsonian Contributions to Paleobiology 93 , 149 162. 1788 [20] Koretsky, I.A. & Holec, P. 2002 A primitive seal (Mammalia: Phocidae) from 1789 the early middle Miocene of central Paratethys. Smithsonian Contributions to 1790 Paleobiology 93 , 163 178. 1791 [21] Koretsky, I.A. & Rahmat, S.J. 2013 First record of fossil Cystophorinae 1792 (Carnivora, Phocidae): middle Miocene seals from the northern Paratethys. Rivista 1793 Italiana di Paleontologia e Stratigrafia 119 , 325 350. 1794 [22] Wyss, A.R. 1988 On "retrogression" in the evolution of the Phocinae and 1795 phylogenetic affinities of the monk seals. American Museum Novitates 2924 , 1 38. 1796 [23] Wiens, J.J. 1999 Polymorphism in systematics and conservation biology. Annual 1797 Review of Ecology and Systematics 30 , 327 362. 1798 [24] Goloboff, P.A., Farris, J.S. & Nixon, K.C. 2008 TNT, a free program for 1799 phylogenetic analysis. Cladistics 24 , 774 786. 1800 [25] Arnason, U., Gullberg, A., Janke, A., Kullberg, M., Lehman, N., Petrov, E.A. & 1801 Väinölä, R. 2006 Pinniped phylogeny and a new hypothesis for their origin and 1802 dispersal. Molecular Phylogenetics and Evolution 41 , 345 354. 1803 [26] Fulton, T.L. & Strobeck, C. 2010 Multiple markers and multiple individuals 1804 refine seal phylogeny and bring molecules and morphology back in line. Proceedings 1805 of the Royal Society B: Biological Sciences 277 , 1065 1070.
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1806 [27] Barnes, L.G. 1989 A new enaliarctine pinniped from the Astoria Formation, 1807 Oregon, and a classification of the Otariidae (Mammalia: Carnivora). Contributions in 1808 Science, Natural History Museum of Los Angeles County 403 , 1 28. 1809 [28] Taxonomy, C.o. 2014 List of marine mammal species and subspecies. Society for 1810 Marine Mammalogy www.marinemammalscience.org , consulted on 10/10/2014. 1811 [29] Prothero, D.R., Bitboul, C.Z., Moore, G.W. & Moore, E.J. 2001 Magnetic 1812 stratigraphy of the lower and middle Miocene Astoria Formation, Lincoln County, 1813 Oregon. Pacific Section SEPM Special Publication 91 , 272 283. 1814 [30] Prothero, D.R., Bitboul, C.Z., Moore, G.W. & Niem, A.R. 2001 Magnetic 1815 stratigraphy and tectonic rotation of the Oligocene Alsea, Yaquina, and Nye 1816 formations, Lincoln County, Oregon. Pacific Section SEPM Special Publication 91 , 1817 184 194. 1818 [31] Barnes, L.G. 1990 A new Miocene enaliarctine pinniped of the genus 1819 Pteronarctos (Mammalia: Otariidae) from the Astoria Formation, Oregon. 1820 Contributions in Science, Natural History Museum of Los Angeles County 422 , 1 20. 1821 [32] Barnes, L.G. 1992 A new genus and species of middle Miocene enaliarctine 1822 pinniped (Mammalia, Carnivora, Otariidae) from the Astoria Formation in coastal 1823 Oregon. Contributions in Science, Natural History Museum of Los Angeles County 1824 431 , 1 27. 1825 [33] Kellogg, R. 1931 Pelagic mammals from the Temblor Formation of the Kern 1826 River region, California. Proceedings of the California Academy of Sciences 19 , 217 1827 397. 1828 [34] Mitchell, E.D. 1961 A new walrus from the imperial Pliocene of Southern 1829 California: with notes on odobenid and otariid humeri. Contributions in Science 44 , 1 1830 28. 1831 [35] Repenning, C.A. & Tedford, R.H. 1977 Otarioid seals of the Neogene. US 1832 Geological Survey Professional Paper 992 , 1 87. 1833 [36] Barnes, L.G. 1988 A new fossil pinniped (Mammalia: Otariidae) from the middle 1834 Miocene Sharktooth Hill Bonebed, California. Contributions in Science 396 , 1 11. 1835 [37] Pyenson, N.D., Irmis, J.H., Lipps, J.H., Barnes, L.G., Mitchell, E.D. & McLeod, 1836 S.A. 2009 The origin of a widespread marine bonebed deposited during the middle 1837 Miocene Climatic Optimum. Geology 37 , 519 522. (doi:10.1130/G25509A.1). 1838 [38] Howard, H. & Barnes, L.G. 1987 Middle Miocene marine birds from the 1839 foothills of the Santa Ana Mountains, Orange County, California. Natural History 1840 Museum of Los Angeles County Contributions in Science 383 , 1 9. 1841 [39] Raschke, R.E. 1984 Early and Middle Miocene vertebrates from the Santa Ana 1842 Mountains, California. Memoirs of the Natural History Foundation of Orange County 1843 1, 61 67. 1844 [40] Whistler, D.P. & Lander, E.B. 2003 New Late Uintan to Early Hemingfordian 1845 land mammal assemblages from the Undifferentiated Sespe and Vaqueros Formations, 1846 Orange County, and from the Sespe and equivalent marine formations in Los Angeles, 1847 Santa Barbara, and Ventura Counties, Southern California. Bulletin of the American 1848 Museum of Natural History 279 , 231 268. 1849 [41] Tedford, R.H., Albright, L.B., III,, Barnosky, A.D., Ferrusquia Villafranca, H., 1850 R.M. Jr., Swisher, C.C., III,, Voorhies, M.R., Webb, S.D. & Whistler, D.P. 2004 1851 Mammalian biochronology of the Arikareean through Hemphillian interval (Late 1852 Oligocene through Early Pliocene epochs). In Late Cretaceous and Cenozoic 1853 Mammals of North America: Biostratigraphy and Geochronology (ed. M.O. 1854 Woodburne), pp. 169 231. New York, Columbia University Press.
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1855 [42] Turner, D.L. 1970 Potassium argon dating of Pacific Coast Miocene 1856 foraminiferal stages. Geological Society of America Special Paper 124 , 91 129. 1857 [43] Barron, J.A. & Isaacs, C.M. 2001 Updated chronostratigraphic framework for the 1858 California Miocene. In The Monterey Formation - from rocks to molecules (eds. C.M. 1859 Isaacs & J. Rullkötter), pp. 393 395. New York, New York, Columbia University 1860 Press. 1861 [44] Mitchell, E.D. 1968 The Mio Pliocene pinniped Imagotaria . Journal of the 1862 Fisheries Research Board of Canada 25 , 1843 1900. 1863 [45] Barron, J.A. 1986 Updated diatom biostratigraphy for the Monterey Formation of 1864 California. In Siliceous Microfossil and Microplankton of the Monterey Formation 1865 and Modern Analogs (eds. R.E. Casey & J.A. Barron), pp. 105 120. Los Angeles, CA, 1866 Pacific Section SEPM. 1867 [46] Barron, J.A. 1975 Marine diatom biostratigraphy of the upper Miocene lower 1868 Pliocene strata of Southern California. Journal of Paleontology 49 , 619 632. 1869 [47] Kellogg, R. 1925 New pinnipeds from the Miocene diatomaceous earth near 1870 Lompoc, California. Contributions to Palaeontology from the Carnegie Institution of 1871 Washington 348 , 71 95. 1872 [48] Chang, A.S., Grimm, K.A. & White, L.D. 1998 Diatomaceous sediments from 1873 the Miocene Monterey Formation, California: a lamina scale investigation of 1874 biological, ecological, and sedimentary processes. Palaios 13 , 439 458. 1875 [49] Whitmore, F.C. & Barnes, L.G. 2008 The Herpetocetinae, a new subfamily of 1876 extinct baleen whales (Mammalia, Cetacea, Cetotheriidae). Virginia Museum of 1877 Natural History Special Publication 14 , 141 180. 1878 [50] Beyer, L.A., McCulloh, T.H., Denison, R.E., Morin, R.W., Enrico, R.J., Barron, 1879 J.A. & Fleck, R.J. 2009 Post Miocene right separation on the San Gabriel and 1880 Vasquez Creek Faults, with supporting chronostratigraphy, western San Gabriel 1881 Mountains, California. US Geological Survey Professional Paper 1759 , 1 43. 1882 [51] Berkoff, M. & Barnes, L.G. 1998 The evolution of the dusignathines: pseudo 1883 walruses of the late Miocene. PaleoBios 18 , 1 2. 1884 [52] Lyon, G.M. 1941 A Miocene sea lion from Lomita, California. University of 1885 California Publications in Zoology 47 , 23 41. 1886 [53] Blake, G.H. 1991 Review of the Neogene Biostratigraphy and stratigraphy of the 1887 Los Angeles Basin and implications for basin evolution. American Association of 1888 Petroleum Geologists Memoir 52 , 135 184. 1889 [54] Magallanes, I., Boessenecker, R.W. & Parham, J.F. 2014 A nearly complete 1890 fossil walrus from Southern California and its implications for odobenid phylogeny. 1891 In Secondary Adaptations of Tetrapods to Life in the Water (ed. M.D. Uhen). Fairfax, 1892 VA, George Mason University 1893 1894 [55] Barnes, L.G. & Minch, J.A. 1995 A new genus and species of late Miocene 1895 imagotariine pinniped from Orange County, California. Journal of Vertebrate 1896 Paleontology 15 , 17A. 1897 [56] Kohno, N. & Ray, C.E. 2008 Pliocene walruses from the Yorktown Formation of 1898 Virginia and North Carolina, and a systematic revision of the North Atlantic Pliocene 1899 walruses. Virginia Museum of Natural History Special Publication 14 , 39 80. 1900 [57] Miyazaki, S., Horikawa, H., Kohno, N., Hirota, K., Kimura, M., Hasegawa, Y., 1901 Tomida, Y., Barnes, L.G. & Ray, C.E. 1995 Summary of the fossil record of 1902 pinnipeds of Japan, and comparisons with that from the eastern North Pacific. The 1903 Island Arc , 361 372.
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1904 [58] Miyazaki, S., Kimura, M. & Ishiguri, H. 1992 On a Pliocene walrus ( Odobenus 1905 sp.) discovered in the Northern Pacific Ocean. The Journal of the Geological Society 1906 of Japan 98 , 723 740. 1907 [59] Koizumi, I. 1985 Diatom biochronology for late Cenozoic northwest Pacific. 1908 Journal of the Geological Society of Japan 91, 195 211. 1909 [60] Akiba, F. 1986 Middle Miocene to Quaternary diatom biostratigraphy in the 1910 Nankai trough and Japan trench, and modified lower Miocene through Quaternary 1911 diatom zones for middle to high latitudes of the North Pacific. Initial reports of the 1912 Deep Sea Drilling Program 87 , 393 481. 1913 [61] Barron, J.A. & Gladenkov, A.Y. 1995 Early Miocene to Pleistocene Diatom 1914 Stratigraphy of Leg 145. Proceedings of the Ocean Drilling Program, Scientific 1915 Results 145 , 3 19. 1916 [62] Kohno, N., Tomida, Y., Hasegawa, Y. & Furusawa, H. 1995 Pliocene tusked 1917 odobenids (Mammalia: Carnivora) in the Western North Pacific, and their 1918 paleobiogeography. Bulletin of the National Science Museum, Tokyo Series C 1919 (Geology & Paleontology) 21 , 111 131. 1920 [63] Harington, C.R. 1977 Marine mammals in the Champlain Sea and the Great 1921 Lakes. Annals of the New York Academy of Sciences 288 , 508 537. 1922 [64] Harington, C.R. 2008 Evolution of Arctic marine mammals. Ecological 1923 Applications 18 , S23 S40. 1924 [65] Post, K. 2005 A Weichselian marine mammal assemblage from the southern 1925 North Sea. Deinsea 11 , 21 27. 1926 [66] Sanders, A.E. 2002 Additions to the Pleistocene mammal faunas of South 1927 Carolina, North Carolina, and Georgia. Transactions of the American Philosophical 1928 Society 92 , 1 152. 1929 [67] Morgan, G.S. 1994 Miocene and Pliocene marine mammal faunas from the Bone 1930 Valley Formation of central Florida. Proceedings of the San Diego Society of Natural 1931 History 29 , 239 268. 1932 [68] Morgan, G.S. & Hulbert, R.C. 1995 Overview of the geology and vertebrate 1933 biochronology of the Leisey Shell Pit Local Fauna, Hillsborough County, Florida. 1934 Bulletin of the Florida Museum 1935 of Natural History 37 , 1 92. 1936 [69] Barnes, L.G. 2008 Otarioidea. In Evolution of Tertiary Mammals of North 1937 America, Volume 2: Small Mammals, Xenarthrans, and Marine Mammals (eds. C.M. 1938 Janis, G.F. Gunnell & M.D. Uhen), pp. 523 541. Cambridge, Cambridge University 1939 Press. 1940 [70] Barnes, L.G. 1987 An early Miocene pinniped of the genus Desmatophoca 1941 (Mammalia: Otariidae) from Washington. Contributions in Science, Natural History 1942 Museum of Los Angeles County 382 , 1 20. 1943 [71] Kellogg, R. 1922 Pinnipeds from Miocene and Pleistocene deposits of California. 1944 University of California Publications in Geological Sciences 13 , 23 132. 1945 [72] Mitchell, E.D. 1966 The Miocene pinniped Allodesmus . University of California 1946 Publications in Geological Sciences 61 , 1 105. 1947 [73] Barnes, L.G. 1972 Miocene Desmatophocinae (Mammalia: Carnivora) from 1948 California. University of California Publications in Geological Sciences 89 , 1 76. 1949 [74] Barnes, L.G. & Hirota, K. 1995 Miocene pinnipeds of the otariid subfamily 1950 Allodesminae in the North Pacific Ocean: Systematics and relationships. The Island 1951 Arc 3, 329 360. 1952 [75] Clark, J.C., Brabb, E.E., Greene, H.G. & Ross, D.C. 1984 Geology of Point 1953 Reyes Peninsula and implications for San Gregorio Fault history. In Tectonics and
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2053 mollusks, Pacific coast United States. U.S. Geological Survey Open-file Report 78- 2054 701 , 445 448. 2055 [109] Roth, B. 1979 Late Cenozoic marine invertebrates from northwest California 2056 and southwest Oregon. Berkeley, California, University of California. 2057 [110] Valenzuela Toro, A.M., Gutstein, C.S., Varas Malca, R.M., Suarez, M.E. & 2058 Pyenson, N.D. 2013 Pinniped turnover in the South Pacific Ocean: new evidence 2059 from the Plio Pleistocene of the Atacama Desert, Chile. Journal of Vertebrate 2060 Paleontology 33 , 216 223. 2061 [111] Drehmer, C.J. & Ribeiro, A.M. 1998 A temporal bone of an Otariidae 2062 (Mammalia: Pinnipedia) from the late Pleistocene of Rio Grande do Sul State, Brazil. 2063 Geociencias 3, 39 44. 2064 2065 2066
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