Skull of 'Diacodexis' pakistanensis, from here.

Belongs within: Cetferungulata.
Contains: Tylopoda, Choeropotamoidea, Suina, Anthracotherioidea, Cetacea, Ruminantia.

Cetartiodactyla has become the generally accepted name for the clade containing the even-toed hoofed mammals (artiodactyls) and the cetaceans, which are nested well within the artiodactyls. Most recent studies place the cetaceans closest to the Hippopotamidae among living artiodactyls, with the two in turn often sister to the Ruminantia (the tree below, taken from Boisserie et al. 2005, differs in placing them closer to the Suina). Among fossil artiodactyls, the earliest Eocene representatives have been assigned to Diacodexis; however, phylogenetic analyses have indicated that this genus is para-/polyphyletic with regard to other artiodactyls.

Synapomorphies (from Prothero et al. 1988*): lower molar trigonids very narrow, paraconid and metaconid closely appressed; alisphenoid canal absent; pars facialis of lacrimal enlarged; orbitosphenoid enlarged, separating frontal from alisphenoid; paraxonic foot, double-pulley astragalus, enlarged third and fourth metapodials, symmetrically reduced second and fifth metapodials.

*Prothero et al. did not ally cetaceans with the artiodactyls, but the nested position of cetaceans means that they probably do not majorly affect the estimated synapomorphies for Cetartiodactyla as a whole.

<==Cetartiodactyla [Ancodonta, Artiodactyla, Bunodontia, Neoselenodontia, Palaeodonta, Selenodontia, Suiformes]
    |--+--‘Diacodexis’ metsiacus GH88
    |  `--Leptochoeridae GH88
    `--+--‘Diacodexis’ pakistanensis Thewissen, Russell et al. 1983 O01, SL00
       `--+--Bunomerycidae GH88
          |    |--Bunomeryx Wortman 1898 GH88
          |    |--Hylomeryx Peterson 1919 GH88
          |    |--Mytonomeryx Gazin 1955 GH88
          |    `--Pentacemylus Peterson 1931 GH88
          `--+--Oreodonta GH88
             |    |  i. s.: Oreodon culbertsonii C76
             |    |--Mixtotherium [Mixotheriidae] GH88
             |    |    `--M. mezi Schmidt 1913 S68
             |    `--Merycoidodontoidea GH88
             |         |--Agriochoerus O01 [Agriochoeridae GH88]
             |         |    `--A. latifrons H07
             |         `--Merycoidodon JJ84 [Merycoidodontidae GH88]
             |              `--M. gracilis H07
             `--+--Tylopoda O01
                `--+--Diacodexis Cope 1881 TW01, SL00
                   |    |--D. secans (Cope 1881) SL00
                   |    `--D. varleti Sudre, Russell et al. 1983 SL00
                   `--+--Khirtharia dayi TW01
                      `--+--Gervachoerus TW01
                         `--Dichobunoidea GH88
                              |--+--Choeropotamoidea BLB05
                              |  `--+--+--Suina BLB05
                              |     |  `--Entelodontidae BLB05
                              |     |       |--Dinohyus JJ84
                              |     |       |--Paraentelodon macrognathus DW04
                              |     |       `--Archaeotherium BLB05
                              |     `--Cetancodonta AA02
                              |          |  i. s.: Raoellidae GH88
                              |          |--+--Anthracotherioidea BLB05
                              |          |  `--Helohyidae BLB05
                              |          |       |--Helohyus GH88
                              |          |       |--Gobiohyus orientalis Matthew & Granger 1925 GH88, SL00
                              |          |       `--Achaenodon GH88
                              |          `--Cetacea BLB05
                              `--Merycotheria [Dichobunidae] GH88
                                   |  i. s.: Aumelasia Sudre 1980 SL00
                                   |         Protodichobune Lemoine 1878 SL00
                                   |           `--*P. oweni Lemoine 1878 SL00
                                   |         Gujaratia pakistanensis WR07
                                   |--Messelobunodon GH88
                                   |--Homacodontidae [Homacodontinae] SL00
                                   |    |--Hexacodus pelodes Gazin 1952 SL00
                                   |    `--Homacodon GH88
                                   |--Dichobuninae GH88
                                   |    |--Dichobune Cuvier 1822 GH88
                                   |    |--Meniscodon Rütimeyer 1888 GH88
                                   |    `--Metriotherium Filhol 1882 GH88
                                   |--Sarcolemur Cope 1875 C76 [incl. Antiacodon Marsh 1872 (n. n.) GH88, C76]
                                   |    |--*S. furcatus C76
                                   |    |--S. crassus (Cope 1875) [=Antiacodon crassus] C76
                                   |    |--S. mentalis (Cope 1875) [=Antiacodon mentalis] C76
                                   |    `--S. pygmaeus C76
                                   `--+--Ruminantia BLB05
                                      `--Hyperdichobuninae GH88
                                           |--Hyperdichobune Stehlin 1910 GH88
                                           `--Mouillacitherium Filhol 1882 GH88

Cetartiodactyla incertae sedis:
  Heptacodon GH01
  Siamotragulus CJ03
  Merychyus Leidy 1858 C76
    |--M. elegans C76
    |--M. major C76
    `--M. medius Leidy 1858 C76
  Wasatchia GH88
  Bunophorus GH88
  Chorlakkia GH88
  Lantianius GH88
  Texodon GH88

*Type species of generic name indicated


[AA02] Arnason, U., J. A. Adegoke, K. Bodin, E. W. Born, Y. B. Esa, A. Gullberg, M. Nilsson, R. V. Short, X. Xu & A. Janke. 2002. Mammalian mitogenomic relationships and the root of the eutherian tree. Proceedings of the National Academy of Sciences of the USA 99 (12): 8151-8156.

[BLB05] Boisserie, J.-R., F. Lihoreau & M. Brunet. 2005. The position of Hippopotamidae within Cetartiodactyla. Proceedings of the National Academy of Sciences of the USA 102 (5): 1537-1541.

[CJ03] Chaimanee, Y., D. Jolly, M. Benammi, P. Tafforeau, D. Duzer, I. Moussa & J.-J. Jaeger. 2003. A Middle Miocene hominoid from Thailand and orangutan origins. Nature 422: 61-65.

[C76] Cope, E. D. 1876. Report upon the extinct Vertebrata obtained in New Mexico by parties of the expedition of 1874. Geographical Surveys West of the One Hundredth Meridian 4 (2): i-iv, 1-370.

[DW04] Deng T., Wang X., Ni X. & Liu L. 2004. Sequence of the Cenozoic mammalian faunas of the Linxia Basin in Gansu, China. Acta Geologica Sinica (English Edition) 78 (1): 8-14.

[GH88] Gentry, A. W., & J. J. Hooker. 1988. The phylogeny of the Artiodactyla. In The Phylogeny and Classification of the Tetrapods, vol. 2. Mammals (M. J. Benton, ed.) pp. 235-272. Clarendon Press: Oxford.

[GH01] Gingerich, P. D., M. ul Haq, I. S. Zalmout, I. H. Khan & M. S. Malkani. 2001. Origin of whales from early artiodactyls: Hands and feet of Eocene Protocetidae from Pakistan. Science 293: 2239-2242.

[H07] Hooker, J. J. 2007. Bipedal browsing adaptations of the unusual Late Eocene-earliest Oligocene tylopod Anoplotherium (Artiodactyla, Mammalia). Zoological Journal of the Linnean Society 151 (3): 609-659.

[JJ84] Janis, C., & P. J. Jarman. 1984. The hoofed mammals. In All the World’s Animals: Hoofed Mammals (D. Macdonald, ed.) pp. 28-39. Torstar Books: New York.

[O01] O’Leary, M. A. 2001. The phylogenetic position of cetaceans: Further combined data analyses, comparisons with the stratigraphic record and a discussion of character optimization. American Zoologist 41: 487-506.

Prothero, D. R., E. M. Manning & M. Fischer. 1988. The phylogeny of the ungulates. In The Phylogeny and Classification of the Tetrapods, vol. 2. Mammals (M. J. Benton, ed.) pp. 201-234. Clarendon Press: Oxford.

[S68] Simons, E. L. 1968. African Oligocene mammals: introduction, history of study, and faunal succession. Peabody Museum of Natural History, Yale University, Bulletin 28: 1-21.

[SL00] Sudre, J., & G. Lecomte. 2000. Relations et position systématique du genre Cuisitherium Sudre et al., 1983, le plus dérivé des artiodactyles de l’Éocène inféreur d’Europe. Geodiversitas 22 (3): 415-432.

[TW01] Thewissen, J. G. M., E. M. Williams, L. J. Roe & S. T. Hussain. 2001. Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature 413: 277-281.

[WR07] Wible, J. R., G. W. Rougier, M. J. Novacek & R. J. Asher. 2007. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary. Nature 447: 1003-1006.

1 comment:

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