Mixotoxodon

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Mixotoxodon
Temporal range: Pleistocene
Mixotoxodon.jpg
Mixotoxodon larensis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Notoungulata
Family: Toxodontidae
Subfamily: Haplodontheriinae
Genus: Mixotoxodon
van Frank, 1957
Species: M. larensis
Binomial name
Mixotoxodon larensis
van Frank, 1957
Mixotoxodon distribution.svg
Some locations where Mixotoxodon fossils have been found.
Synonyms

?Mixotoxodon larensis crusafonti

Mixotoxodon ("mixture Toxodon") is an extinct genus of notoungulate of the family Toxodontidae inhabiting South America, Central America and parts of southern North America during the Pleistocene, from 1,800,000—23,000~25,000 BCE.[1][2]

Description[edit]

Hypothetical reconstruction of the skull of M. larensis, based in different specimens.

Mixotoxodon is known by fragmentary remains, usually mandible fragments and teeth. Although the general appearance probably was very similar to another toxodontid from the Pleistocene, the better known Toxodon, their fossils shown that the outer borders of the symphysis in the lower jaw don't diverge anteriorly, and the incisors form a semicircular structure that protrude less than the incisors of Toxodon; the snout was cylindrical, instead of the broad hippo-like muzzle of Toxodon. The straight snout and the narrow lower incisors closely packed, suggest that this animal had a different feeding strategy compared to their southern relative, although the teeth of both genera was adapted to deal with abrasive food.[3] It was a rhino-sized animal, with a weight of up to 3.8 tonnes, which make it the largest member of Notoungulata.[4]

Mixotoxodon is known from a single species M. larensis. Mixotoxodon is the only notoungulate known to have migrated out of South America during the Great American Interchange. Its fossils have been found in northern South America, in Central America,[5][6] in Veracruz and Michoacán, Mexico (with a possible find in Tamaulipas),[7][8][9] and eastern Texas, USA.[10] The genus was also one of the last surviving notoungulates, along with related genera such as the better-known Toxodon. The name refers to the fact that Mixotoxodon combines characteristics typical of different toxodontid subfamilies.[11]

Phylogeny[edit]

The cladogram below is based in the study made by Analía Forasiepi and colleagues (2014), showing the position of Mixotoxodon inside Toxodontidae:[12]



Pampahippus arenalesi





Rhynchippus spp.




Scarritia 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















Fossil distribution[edit]

This list indicates the countries and places where Mixotoxodon fossils have been found. The list follows Rincón, 2011,[13] unless otherwise indicated:

Notes[edit]

  1. ^ Paleobiology Database: Mixotoxodon, Basic info.
  2. ^ "NEW REMAINS OF Mixotoxodon larensis Van Frank 1957 (Mammalia: Notoungulata) FROM MENE DE INCIARTE TAR PIT, NORTH-WESTERN VENEZUELA Ascanio D. Rincó" (PDF). 
  3. ^ Paula-Couto, 1979, p. 404.
  4. ^ Elissamburu, 2012, p. 108.
  5. ^ McKenna & Bell, 1997, p. 461; Cisneros, 2005, p. 246.
  6. ^ "NEW REMAINS OF Mixotoxodon larensis Van Frank 1957 (Mammalia: Notoungulata) FROM MENE DE INCIARTE TAR PIT, NORTH-WESTERN VENEZUELA Ascanio D. Rincó" (PDF). 
  7. ^ Arroyo-Cabrales et al., 2010, pp. 193-194
  8. ^ "A New Occurrence of Toxodonts in the Pleistocene of México". ResearchGate. Retrieved 2016-01-23. 
  9. ^ Lucas, Spencer G.; Morgan, Gary S.; Spielmann, Justin A.; Prothero, Donald R. (2008-01-01). Neogene Mammals: Bulletin 44. New Mexico Museum of Natural History and Science. 
  10. ^ Lundelius et al., p. 229.
  11. ^ van Frank, 1957, p. 6.
  12. ^ 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. doi:10.1007/s12542-014-0233-5. 
  13. ^ Rincón 2011, p. 896.
  14. ^ Lundelius et al., 2013, p.229
  15. ^ Chimento & Agnolin, 2011, p. 90.

References[edit]