Reconstruction of Embolotherium andrewsi with size comparison to average human, copyright Tim Bertelink.

Belongs within: Euungulata.
Contains: Equoidea, Ceratomorpha, Brontotheriidae, Chalicotheriidae.

The Perissodactyla include the odd-toed hoofed mammals: horses, tapirs and rhinoceroses, as well as their fossil relatives the chalicotheres and brontotheres. Modern perissodactyls are relatively large herbivorous mammals with hind-gut fermenting digestive systems. The Brontotheriidae are a group of rhinoceros-like animals known from the Eocene of North America and Eurasia.

Synapomorphies (from Hooker & Dashzeveg 2004): Upper molar paraconule situated distinctly more mesially than protocone, facet 2A occupying paraconule and part of preprotocrista, notched preprotocrista mesiobuccally directed towards paraconule, lower molar metaconid widely twinned with tips bearing facet 2A; upper molar metaconule distinctly mesial of line drawn between metacone and hypocone, lower molar hypoconulid separated from and distal of crest joining hypoconid and entoconid, M3 with hypocone; upper molar parastyle large; M3 not smaller than M2, M3 larger than M2; upper molars with metaconal fold not joined to metaconule; upper molar metaloph and lower molar hypolophid, especially on M3, oblique.

Perissodactyla [Ancylopoda, Euperissodactyla, Lophodontomorpha, Mesaxonia, Moropomorpha, Selenida, Tapiromorpha]
    |  i. s.: SymborodonC77
    |         Orotherium Marsh 1872C77
    |           |--O. cristonense Cope 1877C77
    |           |--O. laevii Cope 1877C77
    |           `--O. vintanum Marsh 1872C77
    |         Orientolophus Ting 1993HD04
    |           |--*O. hengdongensis Ting 1993HD04
    |           `--O. namadicus (Dashzeveg 1979) [=Homogalax namadicus]HD04
    |         Mesolambdolophus setoniHUG17
    |--Hallensia mathewsiRH14, F02
            |--Homogalax Hay 1899RH14, SM93
            |    |--H. protapirinus [=Systemodon protapirinus]F02
            |    `--H. wutuensisHD04
            `--+--Cardiolophus radinskyi Gingerich 1991RH14, HD04
                  |--Isectolophus Scott & Osborn 1887RH14, SM93
                  |    |--I. annectensRH14
                  |    `--I. latidensRH14
                  |  `--Lambdotherium Cope 1880SM93 [LambdotheriidaeRH14]
                  |       `--L. popoagicumHD04
                       |  i. s.: Kalimantsia Geraards, Spassov & Kovachev 2001D07
                       |           `--K. bulgaricaD07
                       |--Protomoropus Hooker & Dashzeveg 2004HD04
                       |    `--*P. gabuniai (Dashzeveg 1979) [=Hyracotherium gabuniai, Orientolophus gabuniai]HD04
                          |  `--EomoropidaeRH14
                          |       |--Eomoropus amarorumRH14
                          |       `--LitolophusRH14
                          |            |--L. gobiensisHUG17
                          |            `--L. mongoliensisRH14
                               |  i. s.: Toxotherium hunteri Wood 1961S96
                               |         Schizotheriodes parvusTPG96
                               |--Paleomoropus Radinsky 1964HD04, SM93
                               |    `--P. jepseni Radinsky 1964HD04
                               `--+--Lophiaspis Deperet 1910HD04, SM93
                                  |    `--L. maurettei Depéret 1910HD04
                                  `--Lophiodon Cuvier 1822HD04, M02 [incl. Saurornis Fischer 1967M02]
                                       |--L. leptorhynchumRH14
                                       |--*Saurornis’ matthesi Fischer 1967M02
                                       `--L. remensisRH14

*Type species of generic name indicated


[C77] Cope, E. D. 1877. 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.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[F02] Froehlich, D. J. 2002. Quo vadis eohippus? The systematics and taxonomy of the early Eocene equids (Perissodactyla). Zoological Journal of the Linnean Society 134: 141–256.

[HUG17] Halliday, T. J. D., P. Upchurch & A. Goswami. 2017. Resolving the relationships of Paleocene placental mammals. Biological Reviews 92 (1): 521–550.

[HD04] Hooker, J. J., & D. Dashzeveg. 2004. The origin of chalicotheres (Perissodactyla, Mammalia). Palaeontology 47 (6): 1363–1386.

[M02] Mlíkovský, J. 2002. Cenozoic Birds of the World. Part 1: Europe. Ninox Press: Praha.

[RH14] Rose, K. D., L. T. Holbrook, R. S. Rana, K. Kumar, K. E. Jones, H. E. Ahrens, P. Missiaen, A. Sahni & T. Smith. 2014. Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India. Nature Communications 5: 5570.

[S96] Storer, J. E. 1996. Eocene-Oligocene faunas of the Cypress Hills Formation, Saskatchewan. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 240–261. Cambridge University Press.

[SM93] Stucky, R. K., & M. C. McKenna. 1993. Mammalia. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 739–771. Chapman & Hall: London.

[TPG96] Tabrum, A. R., D. R. Prothero & D. Garcia. 1996. Magnetostratigraphy and biostratigraphy of the Eocene-Oligocene transition, southwestern Montana. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 278–311. Cambridge University Press.

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