Phylogenetic Systematics of the North American Fossil Caninae (Carnivora: Canidae)
Total Page：16
File Type：pdf, Size：1020Kb
PHYLOGENETIC SYSTEMATICS OF THE NORTH AMERICAN FOSSIL CANINAE (CARNIVORA: CANIDAE) RICHARD H. TEDFORD Curator Emeritus, Division of Paleontology American Museum of Natural History ([email protected]) XIAOMING WANG Department of Vertebrate Paleontology Natural History Museum of Los Angeles County,California ([email protected]) BERYL E. TAYLOR Frick Curator Emeritus Division of Paleontology American Museum of Natural History BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY Number 325, 218 pp., 71 figures, 7 tables Issued September 3, 2009 Copyright E American Museum of Natural History 2009 ISSN 0003-0090 CONTENTS Abstract.......................................................... 4 Introduction . ...................................................... 5 InstitutionalAbbreviations........................................... 7 ScopeandMethods.................................................. 9 Definitions . ..................................................... 10 ChronologicalFramework........................................... 11 Systematic Paleontology .............................................. 13 SubfamilyCaninaeFischerdeWaldheim,1817............................ 13 Leptocyon Matthew, 1918 ......................................... 14 Leptocyon sp.A............................................... 17 Leptocyon mollis (Merriam),1906.................................. 18 Leptocyon douglassi,newspecies................................... 19 Leptocyon vulpinus (Matthew), 1907 ................................ 22 Leptocyon delicatus (Loomis),1932................................. 25 Leptocyon sp.B............................................... 26 Leptocyon gregorii (Matthew),1907................................. 27 Leptocyon leidyi,newspecies...................................... 31 Leptocyon vafer (Leidy), 1858 . ................................... 34 Leptocyon matthewi,newspecies................................... 43 Leptocyon tejonensis,newspecies................................... 46 Tribe Vulpini Hemprich and Ehrenberg, 1832 ............................. 47 Vulpes Frisch, 1754 .............................................. 47 Vulpes kernensis, new species . ................................... 48 Vulpes stenognathus Savage, 1941................................... 49 Vulpes sp. cf. V. velox (Say),1823.................................. 56 Metalopex TedfordandWang,2008.................................. 58 Metalopex maconnelli, new species.................................. 58 Metalopex merriami TedfordandWang,2008......................... 62 Metalopex bakeri,newspecies..................................... 67 Urocyon Baird,1858............................................. 68 Urocyon webbi, new species ....................................... 69 Urocyon progressus Stevens,1965.................................. 71 Urocyon galushai,newspecies..................................... 72 Urocyon citrinus, new species. ................................... 73 Urocyon minicephalus Martin,1974................................. 75 TribeCaniniFischerdeWaldheim,1817................................. 77 Subtribe Cerdocyonina, new subtribe ................................. 78 Cerdocyon Smith, 1839 .......................................... 78 Cerdocyon texanus, new species .................................. 79 Cerdocyon? avius Torres and Ferrusquı´a, 1981 ....................... 82 Chrysocyon Smith,1839......................................... 83 Chrysocyon nearcticus, new species................................ 84 Theriodictis Mercerat,1891....................................... 88 Theriodictis? floridanus,newspecies................................. 88 Subtribe Canina Fischer de Waldheim, 1817, new rank..................... 89 Eucyon TedfordandQiu,1996.................................... 89 Eucyon? skinneri, new species ................................... 90 Eucyon davisi (Merriam),1911................................... 92 Canis Linnaeus,1758.......................................... 104 Canis ferox Miller and Carranza-Castan˜eda,1998.................... 105 Canis lepophagus Johnston,1938................................ 112 2 2009 TEDFORD ET AL.: NORTH AMERICAN FOSSIL CANINAE 3 Canis tho¨oides,newspecies.................................... 119 Canis feneus,newspecies..................................... 121 Canis cedazoensis Mooser and Dalquest, 1975....................... 122 Canis edwardii Gazin,1942.................................... 123 Canis latrans Say,1823....................................... 131 Canis armbrusteri Gidley,1913................................. 137 Canis dirus Leidy, 1858....................................... 144 Canis lupus Linnaeus,1758.................................... 148 Xenocyon Kretzoi,1938........................................ 150 Xenocyon texanus (Troxell), 1915................................ 152 Xenocyon lycaonoides Kretzoi,1938.............................. 154 Cuon Hodgson,1837.......................................... 157 Cuon alpinus Pallas,1811..................................... 157 PhyleticAnalysis.................................................. 161 Introduction.............................................. 161 CharacterAnalysis.......................................... 163 Phylogeny................................................ 168 DiscussionandConclusions.......................................... 177 Acknowledgments................................................. 183 References...................................................... 184 Appendix 1. Eurasian Species of Canis UsedinPhyleticAnalysis................ 194 Appendix2.CranialMeasurements..................................... 200 Appendix 3. Statistical Summaries of Dental Measurements.................... 205 Appendix4.MeasurementsofLimbBones............................... 218 ABSTRACT The canid subfamily Caninae includes all the living canids and their most recent fossil relatives. Their sister taxon is the Borophaginae with which they share an important modification of the lower carnassial, namely the presence of a bicuspid talonid, which gives this tooth an additional function in mastication. Contributing to thisfunctionisthe enlargement of the posterolingual cingulum of M1 and development of a hypocone. The Caninae diverged from the Borophaginae in the narrowing and elongation of the premolars separated by diastemata and placed in a shallow ramus and narrow muzzle. These latter features allow the Caninae to be recognized in the fossil record as early as the beginning of the Oligocene (34 Ma) and constitute evidence that they represent a monophyletic group. In striking contrast to the history of the Borophaginae, the Caninae remain confined to a closely similar group of fox-sized species (Leptocyon spp.) throughout the Oligocene and showing very limited cladogenesis into the end of the medial Miocene (12 Ma), a span that saw marked adaptive divergence in the Borophaginae and the origin of all its major clades. By 12 Ma (beginning of the Clarendonian Land Mammal age) few fox-sized borophagines remained and most of those held hypocarnivorus adaptations. At that point the Vulpini appear both as mesocarnivores (Vulpes spp.) and hypocarnivores (Metalopex spp.) reproducing, on a much smaller scale, the range of adaptations shown in the initial radiation of the Borophaginae. By the end of the Clarendonian (9 Ma) the first members of the tribe Canini appear. Initially this group was represented by the genus Eucyon, largely by a single widespread North American species E. davisi. Our cladistic analysis predicts that the roots of the South American clade subtribe Cerdocyonina, sister taxon to E. davisi and Canis species (together, subtribe Canina), must also have been present, but taxa representing this group do not appear in the North America record until the earliest Pliocene (latest Hemphillian, 5 Ma). Species of three genera (Cerdocyon, Chrysocyon, and possibly Theriodictis), now confined to South America, appear in the fossil record of the southern United States and northern Mexico prior to and just after the opening of the Panamanian Isthmus (ca. 3 Ma), indicating that important cladogenesis within the South American clade took place in North America. Species of Eucyon make their appearance in the Old World in the late Miocene, and E. davisi has a Pliocene record in Asia. Species of this genus undergo a modest adaptive radiation in Eurasia during the Pliocene. In the late Miocene and early Pliocene two species of Canis appear in North America (C. ferox and C. lepophagus), representing the initial cladogenesis within the genus. These animals are all coyote-sized and represent a broadening of body size range within a mesocarnivorous dental adaptation. Toward the end of the Pliocene and into the Pleistocene in North America a curious and rare group of jackal-like species (C. tho¨oides, C. feneus,andC. cedazoensis) seem to form an endemic clade arising near C. lepophagus. These taxa are dentally similar to jackals, especially C. aureus, but share no synapomorphies with them. The early cladogenesis of Canis in the Pliocene of North America produced a somewhat larger form, C. edwardii, that appears in the late Blancan at ca. 3 Ma. It also seems to have a sister relationship with C. lepophagus and with the coyote C. latrans, which appears much later in the record (late Irvingtonian) and quickly becomes distributed across the United States. The golden jackal (C. aureus) shares synapomorphies with the coyote and C. edwardii but does not appear in the fossil