Skeleton of Metamynodon planifrons, from Wikimedia Commons.

Belongs within: Perissodactyla.
Contains: Tapiroidea, Hyracodontidae, Rhinocerotidae.

The Ceratomorpha, tapirs and rhinoceroses, are a group of heavily built odd-toed hoofed mammals. Early representatives were small and possibly include the European Eocene genus Pachynolophus, alternatively placed with the Palaeotheriidae. Karagalax mamikhelensis, known from the early Eocene of Pakistan, is more firmly established as a ceratomorph, resembling later forms in the reduction of the post-canine diastema.

Synapomorphies (from Hooker & Dashzeveg 2004): M3 hypolophid complete; P3 paraconid strong and approaching height of paraconid; upper molars with metaconal fold consistently joined to metaconule forming complete metaloph; lower preultimate molar with hypolophid complete, comprising equal buccal and lingual segments joined into long unnotched loph, with hypoconulid median; post P1 diastema absent.

<==Ceratomorpha [Rhinocerotoidea]
    |--Pachynolophus [Pachynolophidae] HD04
    |    |--P. hookeri Godinot in Godinot et al. 1987 HD04
    |    |--P. lavocati F02
    |    `--P. livinerensis F02
    `--+--Karagalax mamikhelensis HD04
       `--+--Tapiroidea RH14
          `--+--+--Deperetellidae RH14
             |  |    |--Deperetella cristatum RH14
             |  |    |--Pachylophus Tong & Lei 1984 SM93
             |  |    |--Haagella Heissig 1978 SM93
             |  |    `--Teleolophus Matthew & Granger 1925 SM93
             |  |         `--T. medius RH14
             |  `--Lophialetidae RH14
             |       |--Lophialetes expeditus RH14
             |       |--Parabreviodon Reshetov 1975 SM93
             |       |--Kalakotia Ranga Rao 1972 SM93
             |       |--Eoletes Biryukov 1974 SM93
             |       |--Breviodon Radinsky 1965 SM93
             |       |--Simplaletes Qi 1980 SM93
             |       `--Schlosseria Matthew & Granger 1926 SM93
             |            `--S. magister RH14
             `--Rhinocerotoidea W96
                  |  i. s.: Amynodontopsis bodei Stock 1933 W96
                  |--Hyracodontidae W96
                  |--Rhinocerotidae FS15
                  `--Amynodontidae [Amynodontinae] G88
                       |--Gigantamynodon CND05
                       |--Zaisanamynodon Beliaeva 1971 H96
                       |--Megalamynodon regalis H96, P96
                       |--Paramynodon H96
                       |--Procadurcodon Gromova 1960 H96
                       |    `--*P. lrientalis Gromova 1960 H96
                       |--Amynodon Marsh 1877 SM93
                       |    |--A. advenus (Marsh 1875) [incl. A. intermedius] W96
                       |    `--A. reedi Stock 1939 W96
                       |--Cadurcodon Kretzoi 1942 R06, D07
                       |    |--C. ardynense D07
                       |    `--C. saisanensis D07
                       `--Metamynodon Scott & Osborn 1887 [Metamynodontini] D07
                            |--M. chadronensis D07
                            |--M. mckinneyi D07
                            `--M. planifrons D07

Ceratomorpha incertae sedis:
  Alicornops complanatum CS04
  Didermoceros sumatrensis A71
  Amynodentopsis JJ84
  Parelasmotherium DW04
    |--P. linxiaense DW04
    `--P. simplum DW04
  Sinotherium DW04
  Shansirhinus Kretzoi 1942 DW04
    |--*S. brancoi (Schlosser 1903) [=Rhinoceros brancoi] DW04
    `--S. ringstromi Kretzoi 1942 DW04
  Menoceras Troxell 1921 D07
    |--M. arikarensis D07
    `--M. barbouri D07
  Elasmotherium Fischer 1808 FS15, D07
    |--E. caucasicum D07
    |--E. inexpectatum D07
    `--E. sibiricum FS15

*Type species of generic name indicated


[A71] Askew, R. R. 1971. Parasitic Insects. Heinemann Educational Books: London.

[CS04] Chaimanee, Y., V. Suteethorn, P. Jintasakul, C. Vidthayanon, B. Murandat & J.-J. Jaeger. 2004. A new orang-utan relative from the Late Miocene of Thailand. Nature 427: 439–441.

[CND05] Clarke, J. A., M. A. Norell & D. Dashzeveg. 2005. New avian remains from the Eocene of Mongolia and the phylogenetic position of the Eogruidae (Aves, Gruoidea). American Museum Novitates 3494: 1–17.

[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.

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

[FS15] Faurby, S., & J.-C. Svenning. 2015. A species-level phylogeny of all extant and late Quaternary extinct mammals using a novel heuristic-hierarchical Bayesian approach. Molecular Phylogenetics and Evolution 84: 14–26.

[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.

[G88] Gray, J. 1988. Evolution of the freshwater ecosystem: the fossil record. Palaeogeography, Palaeoclimatology, Palaeoecology 62: 1–214.

[H96] Hanson, C. B. 1996. Stratigraphy and vertebrate faunas of the Bridgerian-Duchesnean Clarno Formation, north-central Oregon. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 206–239. Cambridge University Press.

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

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

[P96] Prothero, D. R. 1996. Magnetic stratigraphy and biostratigraphy of the Middle Eocene Uinta Formation, Uinta Basin, Utah. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 3–24. Cambridge University Press.

[R06] Rose, K. D. 2006. The Beginning of the Age of Mammals. John Hopkins University Press: Baltimore.

[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.

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

[W96] Walsh, S. L. 1996. S. Middle Eocene mammal faunas of San Diego County, California. In: Prothero, D. R., & R. J. Emry (eds) The Terrestrial Eocene–Oligocene Transition in North America pp. 75–119. Cambridge University Press.

Last updated: 9 February 2022.

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