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Toxodontidae; Temporal range: Late Oligocene-Holocene (Deseadan-Lujanian); ~27–0.011 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Toxodon platensis
	Skeleton of Nesodon imbricatus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Notoungulata
Clade:	†Eutoxodontia
Family:	†Toxodontidae; Owen 1845
Subfamilies and genera
	†Haplodontheriinae †Abothrodon; †Haplodontherium; †Mesotoxodon; †Ocnerotherium; †Toxodontherium; †Nesodontinae †Adinotherium; †Nesodon; †Palyeidodon; †Posnanskytherium; †Proadinotherium; †Toxodontinae †Andinotoxodon; †Ceratoxodon; †Charruatoxodon; †Chapalmalodon; †Dinotoxodon; †Eutomodus; †Falcontoxodon; †Gyrinodon; †Hemixotodon; †Hyperoxotodon; †Mesenodon; †Minitoxodon; †Mixotoxodon; †Neoadinotherium; †Neotoxodon; †Nesodonopsis; †Nonotherium; †Paratrigodon; †Pericotoxodon; †Piauhytherium; †Pisanodon; †Plesiotoxodon; †Prototrigodon; †Stenotephanos; †Stereotoxodon; †Toxodon; †Trigodon; †Trigodonops; †Xotodon;

*Xotodon sp.* skull at the Museum für Naturkunde, Berlin

Toxodontidae is an extinct family of notoungulate mammals, known from the Oligocene to the Holocene (11,000 BP) of South America,^[1] with one genus, Mixotoxodon, also known from the Pleistocene of Central America and southern North America (as far north as Texas).^[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]

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.^[8]^[9]^[10]

In 2014, a study identifying a new species of toxodontid resolved the families' phylogenetic relations. The below cladogram was found by the study:^[11]

Pampahippus arenalesi

Rhynchippus spp.

	Scarrittia canquelensis

	Leonitinia gaudri

Toxodontidae

Proadinotherium leptognathum

Adinotherium spp.

	Nesodon taweretus

	Nesodon imbricatus

Palyeidodon obtusum

Hyperoxotodon speciosus

	Nonotherium henningi

	Xotodon spp.

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

References

^ Turvey, Samuel T. (2009-05-28). Holocene Extinctions. OUP Oxford. ISBN 9780191579981.
^ 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
^ Cassini, Guillermo H.; Flores, David A.; Vizcaíno, Sergio F. (July 2012). "Postnatal ontogenetic scaling of Nesodontine (Notoungulata, Toxodontidae) cranial morphology: Nesodontine cranial allometry". Acta Zoologica. 93 (3): 249–259. doi:10.1111/j.1463-6395.2011.00501.x. hdl:11336/81335.
^ Nelson, Allison; Engelman, Russell K.; Croft, Darin A. (2023-07-12). "How to weigh a fossil mammal? South American notoungulates as a case study for estimating body mass in extinct clades". Journal of Mammalian Evolution. doi:10.1007/s10914-023-09669-1. ISSN 1064-7554.
^ Gomes Rodrigues, Helder; Herrel, Anthony; Billet, Guillaume (2017-01-31). "Ontogenetic and life history trait changes associated with convergent ecological specializations in extinct ungulate mammals". Proceedings of the National Academy of Sciences. 114 (5): 1069–1074. doi:10.1073/pnas.1614029114. ISSN 0027-8424. PMC 5293108. PMID 28096389.
^ MacFadden, Bruce J. (September 2005). "Diet and habitat of toxodont megaherbivores (Mammalia, Notoungulata) from the late Quaternary of South and Central America". Quaternary Research. 64 (2): 113–124. Bibcode:2005QuRes..64..113M. doi:10.1016/j.yqres.2005.05.003.
^ Pérez-Crespo, Víctor Adrián; Arroyo-Cabrales, Joaquín; Guzmán, Ana Fabiola; Morales-Puente, Pedro; Cienfuegos-Alvarado, Edith; Otero, Francisco J. (2020-01-09). "ISOTOPIC PALEOECOLOGY OF A TOXODONT (MIXOTOXODON LARENSIS) FROM MICHOACAN, MEXICO". The Southwestern Naturalist. 64 (1): 63. doi:10.1894/0038-4909-64-1-63. ISSN 0038-4909.
^ Welker, F.; Collins, M. J.; Thomas, J. A.; Wadsley, M.; Brace, S.; Cappellini, E.; Turvey, S. T.; Reguero, M.; Gelfo, J. N.; Kramarz, A.; Burger, J.; Thomas-Oates, J.; Ashford, D. A.; Ashton, P. D.; Rowsell, K.; Porter, D. M.; Kessler, B.; Fischer, R.; Baessmann, C.; Kaspar, S.; Olsen, J. V.; Kiley, P.; Elliott, J. A.; Kelstrup, C. D.; Mullin, V.; Hofreiter, M.; Willerslev, E.; Hublin, J.-J.; Orlando, L.; Barnes, I.; MacPhee, R. D. E. (2015-03-18). "Ancient proteins resolve the evolutionary history of Darwin's South American ungulates". Nature. 522 (7554): 81–84. Bibcode:2015Natur.522...81W. doi:10.1038/nature14249. hdl:11336/14769. ISSN 0028-0836. PMID 25799987. S2CID 4467386.
^ Buckley, M. (2015-04-01). "Ancient collagen reveals evolutionary history of the endemic South American 'ungulates'". Proceedings of the Royal Society B: Biological Sciences. 282 (1806): 20142671. doi:10.1098/rspb.2014.2671. PMC 4426609. PMID 25833851.
^ Westbury, M.; Baleka, S.; Barlow, A.; Hartmann, S.; Paijmans, J. L. A.; Kramarz, A.; Forasiepi, A. M.; Bond, M.; Gelfo, J. N.; Reguero, M. A.; López-Mendoza, P.; Taglioretti, M.; Scaglia, F.; Rinderknecht, A.; Jones, W.; Mena, F.; Billet, G.; de Muizon, C.; Aguilar, J. L.; MacPhee, R. D. E.; Hofreiter, M. (2017-06-27). "A mitogenomic timetree for Darwin's enigmatic South American mammal Macrauchenia patachonica". Nature Communications. 8: 15951. Bibcode:2017NatCo...815951W. doi:10.1038/ncomms15951. PMC 5490259. PMID 28654082.
^ Forasiepi, A. A. M.; Cerdeño, E.; Bond, M.; Schmidt, G. I.; Naipauer, M.; Straehl, F. R.; Martinelli, A. N. G.; Garrido, A. C.; Schmitz, M. D.; Crowley, J. L. (2014). "New toxodontid (Notoungulata) from the Early Miocene of Mendoza, Argentina". Paläontologische Zeitschrift. 89 (3): 611–634. doi:10.1007/s12542-014-0233-5. hdl:11336/20443. S2CID 129293436.