[2] Member of the family were medium to large-sized,[3] ranging from around 350–400 kilograms (770–880 lb) in Nesodon to 1,000–1,200 kilograms (2,200–2,600 lb) in Toxodon,[4] and had medium to high-crowned dentition, which in derived members of the group evolved into ever-growing cheek teeth.

[5] Isotopic analyses have led to the conclusion that Pleistocene members of the family were flexible mixed feeders (both browsing and grazing).

[6][7] The endemic notoungulate and litoptern ungulates of South America have been shown by studies of collagen and mitochondrial DNA sequences to be a sister group to the perissodactyls.

[8][9][10] In 2014, a study identifying a new species of toxodontid resolved the families' phylogenetic relations.

Andinotoxodon bolivariensis Dinotoxodon paranensis Toxodon platensis Gyrinodon quassus Ocnerotherium intermedium Hoffstetterius imperator Posnanskytherium desaguaderoi Pisanodon nazari Pericotoxodon platignathus Calchaquitherium mixtum Mixotoxodon larensis Paratrigodon euguii Trigodon gaudri