Notoungulata

Skull and reproduction of head of Notopithecus, from here.

Belongs within: Pholidotamorpha.

The Notoungulata were a diverse group of herbivorous mammals found in South America from the Palaeocene to the Pleistocene; a single Pleistocene species Mixotoxodon larensis was found in southern North America following the formation of the Central American land bridge. Various forms might be described as convergent on Northern Hemisphere rhinos, pigs, rabbits or hyraxes. The relations of notoungulates within other mammals remain poorly established; various relationships have been suggested with modern afrotherians and euungulates, and it is debated whether or not notoungulates are directly related to other extinct South American 'ungulates' such as litopterns or astrapotheres.

Characters (from Rose 2006): Early forms with dental formula of 3.1.4.3/3.1.4.3; teeth usually closely spaced, diastema absent; cheek teeth lophodont: upper molars with strong, straight ectoloph, oblique protoloph and more transverse metaloph; tendency to develop extra crests running toward centre of upper molar, including 'crochet' extending anterobuccally from metaloph; lower molars with two main crescentic crests, the metalophid and hypolophid, with shorter transverse entolophid derived from entoconid; paraconid typically absent; paracristid short; ectocingulum usually weak or absent on both upper and lower teeth. Skull with postorbital bar absent, zygomatic arch arising high on back of skull. Ear region with tympanic cavity connected to large epitympanic sinus in squamosal, often also to hypotympanic sinus below tympanic cavity; inflated ectotympanic bulla surrounding tympanic cavity, extending laterally as external auditory tube with ventral crest; fossa present behind bulla for projection of the hyoid. Feet mesaxonic; astragalus with moderately long constricted neck, roughly hemispherical head, medial projection on body, prominent dorsal foramen, posterior sulcus, partly confluent sustentacular and navicular facets; astragalar trochlea slightly grooved with high lateral rim; calcaneal peroneal tubercle distally situated.

Notoungulata
    |--Oldfieldthomasia [Acoelodidae] S32
    |    `--O. debilitata [=Acoelodus debilitatus] S32
    |--Notopithecus [Notopithecidae] S32
    |    `--N. adapinus S32
    `--Notostylops Ameghino 1897 [Notostylopidae] D07
         |--N. brachycephalus S32
         `--N. escaridus S32

Notoungulata incertae sedis:
  Simpsonotus praecursor MC00, OB13
  Thomashuxleya Ameghino 1901 D07
    `--T. externa OB13
  Scarrittia Simpson 1934 D07
    |--S. canquelensis D07
    `--S. robusta D07
  Rhynchippus Soria & Alvarenga 1989 D07
    |--R. brasiliensis D07
    |--R. equinus D07
    `--R. pumulis D07
  Pachyrukhos Ameghino 1885 D07
    `--P. moyani D07
  Archaeohyrax Ameghino 1897 D07
    `--A. patagonicus D07
  Protypotherium Ameghino 1882 D07
    |--P. anomopodus D07
    |--P. australe D07
    `--P. minitum D07
  Homalodotherium Riggs 1930 D07
    |--H. crassum D07
    |--H. cunninghami D07
    |--H. excursum D07
    `--H. segoviae D07
  Trigodon Ameghino 1882 D07
    `--T. gaudryi D07
  0--Mixotoxodon larensis FS15
  `--+--Trigonodops lopesi FS15
     `--Toxodon O05
          |--T. burmeisteri O05
          `--T. platensis FS15

Inorganic: Toxodon plateuse minilorientalus Okamura 1987 O87

*Type species of generic name indicated

REFERENCES

[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.

[MC00] Muizon, C. de, & R. L. Cifelli. 2000. The “condylarths” (archaic Ungulata, Mammalia) from the early Palaeocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates. Geodiversitas 22 (1): 47–150.

[O87] Okamura, C. 1987. New facts: Homo and all Vertebrata were born simultaneously in the former Paleozoic in Japan. Original Report of the Okamura Fossil Laboratory 15: 347–573.

[OB13] O'Leary, M. A., J. I. Bloch, J. J. Flynn, T. J. Gaudin, A. Giallombardo, N. P. Giannini, S. L. Goldberg, B. P. Kraatz, Z.-X. Luo, J. Meng, X. Ni, M. J. Novacek, F. A. Perini, Z. S. Randall, G. W. Rougier, E. J. Sargis, M. T. Silcox, N. B. Simmons, M. Spaulding, P. M. Velazco, M. Weksler, J. R. Wible & A. L. Cirranello. 2013. The placental mammal ancestor and the post-K–Pg radiation of placentals. Science 339: 662–667.

[O05] Outes, F. F. 1905. Sobre un instrumento paleolítico de Luján (Provincia de Buenos Aires). Anales del Museo Nacional de Buenos Aires, serie 3, 6: 169–173.

Rose, K. D. 2006. The Beginning of the Age of Mammals. JHU Press.

[S32] Simpson, G. G. 1932. Skulls and brains of some mammals from the Notostylops beds of Patagonia. American Museum Novitates 578: 1–11.

Last updated: 17 August 2018.