Toxodontidae (from Ancient Greek τόξον (tóxon), meaning "bow", and ὀδούς (odoús), meaning "tooth") is an extinct family of notoungulate mammals, known from the Oligocene to the Holocene (11,000 BP) of South America, with one genus, Mixotoxodon, also known from the Pleistocene of Central America and southern North America (as far north as Texas).E. Lundelius, et al. 2013. The first occurrence of a toxodont (Mammalia, Notoungulata) in the United States. Journal of Vertebrate Paleontology, Vol 33, No 1, pp. 229–232 DOI:10.1080/02724634.2012.711405 Member of the family were medium to large-sized, ranging from around in Nesodon to in Toxodon, and had medium to high-crowned dentition, which in derived members of the group evolved into ever-growing cheek teeth.
Palaeobiology
Palaeoecology Isotopic analyses have led to the conclusion that Pleistocene members of the family were flexible mixed feeders (both browsing and grazing). The family's dietary ecology shifted over time; δ13C ratios show them being mainly browsers in the Miocene and becoming increasingly grazing animals during the Pliocene and especially the Pleistocene epochs.
Taxonomy 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.
In 2014, a study identifying a new species of toxodontid resolved the families' phylogenetic relations. The below cladogram was found by the study:
Cladogram after Armella and Deforel (2026):
References
Further reading McKenna, Malcolm C., and Bell, Susan K. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp.
External links