Mixotoxodon

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Mixotoxodon
Temporal range: ?early to late Pleistocene[1]
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 (De Porta, 1959)[2]

Mixotoxodon ("mixture Toxodon") is an extinct genus of notoungulate of the family Toxodontidae which inhabited South America during the Pleistocene living from 1.8—0.30 Ma and existed for approximately 1.5 million years.[3]

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 the 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 incisives 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.[4] It was a rhino-sized animal, with a weight of up to 3.8 tonnes, which make it the largest member of Notoungulata.[5]

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,[6] in Veracruz and Michoacán, Mexico (with a possible find in Tamaulipas),[7] and southern Texas, USA.[8] 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.[9]

Phylogeny[edit]

The cladogram below is based in the study made by Analía Forasiepi and colleages (2014), showing the position of Mixotoxodon inside Toxodontidae:[10]



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,[11] unless otherwise indicated:

Notes[edit]

  1. ^ McKenna & Bell, 1997, p. 461.
  2. ^ De Porta 1959, p. 55.
  3. ^ Paleobiology Database: Mixotoxodon, Basic info.
  4. ^ Paula-Couto, 1979, p. 404.
  5. ^ Elissamburu, 2012, p. 108.
  6. ^ McKenna & Bell, 1997, p. 461; Cisneros, 2005, p. 246.
  7. ^ Arroyo-Cabrales et al., 2010, pp. 193-194
  8. ^ Lundelius et al., p. 229.
  9. ^ van Frank, 1957, p. 6.
  10. ^ 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.  edit
  11. ^ Rincón 2011, p. 896.
  12. ^ Lundelius et al., 2013, p.229
  13. ^ Chimento & Agnolin, 2011, p. 90.

References[edit]