Toxodon platensis (Owen 1837; Pliocene-Pleistocene 2.6-.016 mya; 2.7 m in length) lost the medial and lateral toes on all four hoofed extremities. That makes it look like a perissodactyl ungulate. The high neural spines and low position of the skull remind one of North American bison. Prehistoric humans hunted toxodons, based on the arrow tips found with skeletons. This taxon nests with the much smaller Eurygenium (below) and Interatherium.

Eurygenium latirostris (Ameghino 1894. E. pacegnum Shokey 1997; late Oligocene, 25 mya;76 cm in length) was described by Shockey as close to the origins of Toxodontidae. That is confirmed here, but no prior authors nested these taxa with interatheres at the base of the kangaroo clade.

Owen R 1837. Description of the cranium of the Toxodon platensis. Proceedings of the Geological Society of London 2:541-542.

Shockey BJ 1997. Two new notoungulates (Family Notohippidae) from the Sall Beds of Bolivia (Deseadan: late Oligocene): systematics and functional morphology. Journal of Vertebrate Paleontology 17(3):584-599.

wiki/Toxodon