| Notoungulata, Toxodontidae, Toxodonta, Toxodon, Nesodon|
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.
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. It was a rhino-sized animal, with a weight of up to 3.8 tonnes, which make it the largest member of Notoungulata.
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, in Veracruz and Michoacán, Mexico (with a possible find in Tamaulipas), and eastern Texas, USA. 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.
The cladogram below is based in the study made by Analía Forasiepi and colleagues (2014), showing the position of Mixotoxodon inside Toxodontidae:
This list indicates the countries and places where Mixotoxodon fossils have been found. The list follows Rincón, 2011, unless otherwise indicated:United States
Harris County, Texas
La Estribera, Veracruz (Polaco et al., 2004).
Santa Amelia River, Petén Department (Woodburne,1969).
Yeroconte, Lempira department (Webb and Perrigo,1984)
Orillas del Humuya, Comayagua department.
Tomayate, San Salvador department (Cisneros, 2005)
Barranca del Sisimico, San Vicente department.
Hormiguero, San Miguel department (Webb and Perrigo, 1984).
El Bosque, Estelí department (Leidy, 1886).
Bajo de los Barrantes, Alajuela province (Laurito, 1993; Valerio, 1939; Spencer et al., 1997).
Ocú, Herrera Province (Gazin, 1956).
Chívolo, Magdalena department (Porta 1959; Villarroel and Clavijo, 2005).
Mene de Inciarte, Zulia State (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)
Juruá River, Acre State (Paula Couto, 1982; Rancy, 1981)
Cara Cara, Beni Department (Hoffstetter, 1968).
Dique Los Quiroga, Santiago del Estero.