''Mixotoxodon'' ("mixture '' Toxodon''") is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of notoungulate of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Toxodontidae inhabiting

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

and parts of southern

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

during the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

epoch, from 1,800,000—12,000 years ago.''Mixotoxodon''
at

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.org

Description

''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 were adapted to deal with abrasive food. It was a rhino-sized animal, a 2012 study estimated a weight of up to , which makes it the largest member of Notoungulata, though this may be an overestimate. ''Mixotoxodon'' is known from a single species, ''M. larensis''. ''Mixotoxodon'' is the only notoungulate known to have migrated out of

during the

Great American Interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which land ...

. Its fossils have been found in northern

, in

,McKenna & Bell, 1997, p. 461; Cisneros, 2005, p. 246. in

Veracruz Veracruz, formally Veracruz de Ignacio de la Llave, officially the Free and Sovereign State of Veracruz de Ignacio de la Llave, is one of the 31 states which, along with Mexico City, comprise the 32 Political divisions of Mexico, Federal Entit ...

and

Michoacán Michoacán, formally Michoacán de Ocampo, officially the Free and Sovereign State of Michoacán de Ocampo, is one of the 31 states which, together with Mexico City, compose the Political divisions of Mexico, Federal Entities of Mexico. The stat ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

(with a possible find in

Tamaulipas Tamaulipas, officially the Free and Sovereign State of Tamaulipas, is a state in Mexico; one of the 31 states which, along with Mexico City, comprise the 32 federal entities of Mexico. It is divided into 43 municipalities. It is located in nor ...

),Arroyo-Cabrales ''et al.'', 2010, pp. 193-194 and eastern

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

, 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.van Frank, 1957, p. 6.

Phylogeny

The

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below is based in the study published by Analía Forasiepi and colleagues (2014), showing the position of ''Mixotoxodon'' inside Toxodontidae:

Fossil distribution

This list indicates the countries and places where ''Mixotoxodon'' fossils have been found. The list follows Rincón, 2011, unless otherwise indicated: ;North America *

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Harris County, Texas Harris County is a county located in the U.S. state of Texas. As of the 2020 United States census, 2020 census, the population was 4,731,145, and was estimated to be 5,009,302 in 2024, making it the List of counties in Texas, most populous cou ...

** Hihuitlán,

** La Estribera,

(Polaco et al., 2004) *

Guatemala Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...

** Santa Amelia River,

Petén Department Petén (from the Itza' language, Itz'a, , 'Great Island') is a Departments of Guatemala, department of Guatemala. It is geographically the northernmost department of Guatemala, as well as the largest by area at it accounts for about one third o ...

(Woodburne, 1969) *

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. It is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Ocean at the Gulf of Fonseca, ...

** Yeroconte, Lempira department (Webb and Perrigo, 1984) ** Orillas del Humuya, Comayagua department *

El Salvador El Salvador, officially the Republic of El Salvador, is a country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, and on the south by the Pacific Ocean. El Salvador's capital and largest city is S ...

** Tomayate, San Salvador department (Cisneros, 2005) ** Cuscatlán Formation, Barranca del Sisimico, San Vicente department ** Hormiguero, San Miguel department (Webb and Perrigo, 1984) *

Nicaragua Nicaragua, officially the Republic of Nicaragua, is the geographically largest Sovereign state, country in Central America, comprising . With a population of 7,142,529 as of 2024, it is the third-most populous country in Central America aft ...

** El Bosque, Estelí department (Leidy, 1886) *

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

** Bajo de los Barrantes,

Alajuela province Alajuela () is a Provinces of Costa Rica, province of Costa Rica. It is located in the north-central part of the country, bordering Nicaragua to the north. It also borders the provinces of Heredia Province, Heredia to the east, San Jose Province, ...

(Laurito, 1993; Valerio, 1939; Spencer et al., 1997) *

Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...

** Ocú,

Herrera Province Herrera () is a province in Panama. Named after General Tomás Herrera, the province was founded on January 18, 1915 from a division of the Los Santos province. The capital city of Herrera is Chitré, which is located near the province's co ...

(Gazin, 1956) ;South America *

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

** Rotinet Formation, Chívolo, Magdalena ( De Porta 1959; Villarroel and Clavijo, 2005) *

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

** 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 Monagas State (, ) is one of the 23 states of Venezuela. Monagas State covers a total surface area of and, as of the 2011 census, had a population of 905,443. Monagas State is surrounded by Sucre State in the north, Anzoátegui State in the ...

(Rincón ''et al''., 2009) *

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

** Juruá River, Acre State (Paula Couto, 1982; Rancy, 1981) ** Araras/Periquitos,

Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). It is bordered by Acre (state), Acre in the west, Amazonas, Brazil, Amazonas in the north, Mato Grosso in the east, and Bo ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

** Cara Cara,

Beni Department Beni (), sometimes El Beni, is a northeastern Departments of Bolivia, department of Bolivia, in the lowlands region of the country. It is the second-largest department in the country (after Santa Cruz), covering 213,564 square kilometers (82,458 ...

( Hoffstetter, 1968) *

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

** Dique Los Quiroga,

Santiago del Estero Santiago del Estero (, Spanish for ''Saint-James-Upon-The-Lagoon'') is the capital of Santiago del Estero Province in northern Argentina. It has a population of 252,192 inhabitants, () making it the twelfth largest city in the country, with a sur ...

Chimento & Agnolin, 2011, p. 90

References

Bibliography and further reading

* * Chimento, Nicolás R., and Federico L. Agnolin
Mamíferos del Pleistoceno Superior de Santiago del Estero (Argentina) y sus afinidades paleobiogeográficas
''Papéis Avulsos de Zoologia'' 51.6 (2011): 83-100. * Cisneros, J.C. 2005
New Pleistocene vertebrate fauna from El Salvador
Revista Brasileira de Paleontologia, 8(3):239-255. * De Porta, Jaime., 1959: Nueva subespecie de Toxodóntido del Cuaternario de Colombia.- ''Boletín de Geolología, Universidad Industrial de Santander'', 3: 55-61. * Elissamburu A., 2012
Estimación de la masa corporal en géneros del Orden Notoungulata
''Estudios Geológicos'', Vol 68, No 1, doi:10.3989/egeol.40336.133 * Laurito, César Alberto
Análisis topológico y sistemático del Toxodonte de Bajo de los Barrantes, provincia de Alajuela, Costa Rica
''Revista Geológica de América Central'' 16 (1993). * Lucas, Spencer G., Guillermo E. Alvarado, and Eduardo Vega
The pleistocene mammals of Costa Rica
''Journal of Vertebrate Paleontology'' 17.2 (1997): 413-427. * * MacFadden, Bruce J. (2005). Diet and habitat of toxodont megaherbivores (Mammalia, Notoungulata) from the late Quaternary of South and Central America. ''Quaternary Research'' 64 (2005) 113 – 124. * McKenna, Malcolm C., and Bell, Susan K. 1997
''Classification of Mammals Above the Species Level''
Columbia University Press, New York, 631 pp. * Paula-Couto, C. (1979). Capítulo XXI, Ordem Notoungulata Roth, 1903. In ''Tratado de Paleomastozoologia''. Academia Brasileira de Ciências, 590 p, Rio de Janeiro. * Rincón, Ascanio D
Los mamíferos fósiles del Pleistoceno de la cueva del Zumbador (fa. 116), Estado Falcón, Venezuela
''Boletín de la Sociedad Venezolana de Espeleología'' 37 (2003): 18-26. * Rincón, Ascanio D
New remains of ''Mixotoxodon larensis'' Van Frank 1957 (Mammalia: Notoungulata) from Mene de Inciarte tar pit, north-western Venezuela
''Interciencia'' 36.12 (2011): 894-899. * Van Frank, R. 1957
A fossil collection from northern . 1, Toxodontidae (Mammalia, Notoungulata)
''American Museum Novitates'', 1850:1-38. * Villarroel A., C. & J. Clavijo ( 2005)
Los mamíferos fósiles y las edades de las sedimentitas continentales del Neógeno de la Costa Caribe Colombiana
''Revista de la Academia Colombiana de Ciencias'' 29 (112): 345-356. ISSN 0370-3908. {{Taxonbar, from=Q141979 Toxodonts Pleistocene first appearances Holocene extinctions Pleistocene mammals of North America Irvingtonian Pleistocene Costa Rica Pleistocene El Salvador Pleistocene Guatemala Pleistocene Honduras Pleistocene Mexico Pleistocene Nicaragua Pleistocene Panama Pleistocene United States Pleistocene mammals of South America Uquian Ensenadan Lujanian Pleistocene Argentina Pleistocene Bolivia Pleistocene Brazil Pleistocene Colombia Pleistocene Venezuela Fossils of Costa Rica Fossils of El Salvador Fossils of Guatemala Fossils of Honduras Fossils of Mexico Fossils of Nicaragua Fossils of Panama Fossils of Argentina Fossils of Bolivia Fossils of Brazil Fossils of Colombia Fossils of Venezuela Fossil taxa described in 1957 Prehistoric placental genera