Mixotoxodon

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Mixotoxodon
Temporal range: Mid-Late Pleistocene (Uquian-Lujanian & Irvingtonian)
~1.8–0.012 Ma
↓
Mixotoxodon.jpg
Mixotoxodon larensis
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
†Notoungulata
Family:
†Toxodontidae
Subfamily:
†Toxodontinae
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—12,000 years ago.[1][2]

Description[]

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

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 makes 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[]

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

 
 

 
 
 
 

Rhynchippus spp.

 
 
 

 
 

Leonitinia gaudri

 
 
 
Toxodontidae
 

 
 
 
 

Adinotherium spp.

 
 
 

Nesodon taweretus

 
 

Nesodon imbricatus

 
 
 
 
 

Palyeidodon obtusum

 
 
 

 
 
 
 

Nonotherium henningi

 
 

Xotodon spp.

 
 
 
 
 

 
 
 
 

 
 

Toxodon platensis

 
 
 
 

 
 
 

 
 

Hoffstetterius imperator

 
 
 
 
 
 
 

 
 
 

Pisanodon nazari

 
 
 

 
 
 
 

 
 

Mixotoxodon larensis

 
 
 
 

Paratrigodon euguii

 
 

Trigodon gaudri

 
 
 
 
 
 
 
 
 
 
 
 
 
 

Fossil distribution[]

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

North America
South America
  • Colombia
    • , Chívolo, Magdalena ( 1959; and Clavijo, 2005)
  • Venezuela
    • Mene de Inciarte, Zulia (Rincón, 2011)
    • Quebrada Ocando, Falcón State (Bocquentin-Villanueva, 1984)
    • Muaco, Falcón State (Royo y Gómez, 1960, Bocquentin-Villanueva, 1979)
    • Cerro Misión, Falcón State (Rincón, 2004)
    • Zumbador Cave, Falcón State
    • Agua Viva del Totumo, Lara State (Karsten, 1886)
    • San Miguel, Lara Sate (Van Frank, 1957)
    • El Tocuyo, Lara State
    • El Breal de Orocual, Monagas State (Rincón et al., 2009)
  • Brazil
    • Juruá River, Acre State (Paula Couto, 1982; Rancy, 1981)
    • Araras/Periquitos, Rondônia
  • Bolivia
  • Argentina

References[]

  1. ^ Mixotoxodon at Fossilworks.org
  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. 89 (3): 611–634. 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

Bibliography and further reading[]


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