''Mixotoxodon'' ("mixture ''

Toxodon ''Toxodon'' (meaning "bow tooth" in reference to the curvature of the teeth) is an extinct genus of South American mammals from the Late Miocene to early Holocene epochs (Mayoan to Lujanian in the SALMA classification) (about 11.6 million to 11 ...

''") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

notoungulate Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resemb ...

of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Toxodontidae Toxodontidae is an extinct family of notoungulate mammals, known from the Oligocene to the Holocene (11,000 BP) of South America, with one genus, ''Mixotoxodon'', also known from the Pleistocene of Central America and southwestern North America ...

inhabiting

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

and parts of southern

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

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

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.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 ''

'', their fossils shown that the outer borders of the

symphysis A symphysis (, pl. symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint. # A symphysis is an amphiarthrosis, a slightly movable joint. # A growing together ...

in the lower jaw don't diverge anteriorly, and the

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, whe ...

s 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 A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species o ...

-sized animal, with a weight of up to , which makes 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

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 lan ...

. 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 ( es, Estado Libre y Soberano de Veracruz de Ignacio de la Llave), is one of the 31 states which, along with Me ...

and

Michoacán Michoacán, formally Michoacán de Ocampo (; Purépecha: ), officially the Free and Sovereign State of Michoacán de Ocampo ( es, Estado Libre y Soberano de Michoacán de Ocampo), is one of the 32 states which comprise the Federal Entities of ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

(with a possible find in

Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...

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

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

, 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 ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

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 (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Harris County, Texas Harris County is a county located in the U.S. state of Texas; as of the 2020 census, the population was 4,731,145, making it the most populous county in Texas and the third most populous county in the United States. Its county seat is Houston, ...

** Hihuitlán,

** La Estribera,

(Polaco et al., 2004) *

Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by H ...

** Santa Amelia River,

Petén Department Petén is a 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 of Guatemala's area. The capital is Flores. The population at the mid-2018 o ...

(Woodburne, 1969) *

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...

** Yeroconte,

Lempira department Lempira is one of the 18 departments in Honduras. located in the western part of the country, it is bordered by the departments of Ocotepeque and Copán to the west, Intibucá to the east, and Santa Bárbara to the north. To its south lies th ...

(Webb and Perrigo, 1984) ** Orillas del Humuya,

Comayagua department Comayagua () is one of the 18 departments ''(departamentos)'' into which Honduras is divided. The departmental capital is Comayagua. Geography The department covers a total surface area of 5,124 km² and, in 2015, had an estimated population ...

El Salvador El Salvador (; , meaning " The Saviour"), officially the Republic of El Salvador ( es, República de 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 b ...

** Tomayate,

San Salvador department San Salvador () is a department of El Salvador in the west central part of the country. The capital is San Salvador, which is also the national capital. The department has North of the Rio Lempa Valley, the "Valle de las Hamacas" (Hammock Valley ...

(Cisneros, 2005) **

Cuscatlán Formation The Cuscatlán Formation is a geologic formation in El Salvador. It preserves fossils dating back to the Pliocene to Middle Pleistocene (Blancan to Irvingtonian) period. Fossil content * ''Borophagus hilli'' * '' Meizonyx salvadorensis'' * '' M ...

, Barranca del Sisimico, San Vicente department ** Hormiguero, San Miguel department (Webb and Perrigo, 1984) *

Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in Central America, bordered by Honduras to the north, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to the west. Managua is the cou ...

** El Bosque,

Estelí department Estelí () is a department of Nicaragua. It covers an area of 2,230 km2 and has a population of 230,953 (2021 estimate). Its capital is the city of Estelí. Municipalities # Condega Condega () is a municipality in the Estelí depart ...

(Leidy, 1886) *

Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...

** Bajo de los Barrantes,

Alajuela province Alajuela () is a 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 to the east, San José to the south, Puntarenas to the southwest and G ...

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

Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...

** 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 coast ...

(Gazin, 1956) ;South America *

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

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

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

** Mene de Inciarte,

Zulia Zulia State ( es, Estado Zulia, ; Wayuu: ''Mma’ipakat Suuria'') is one of the 23 states of Venezuela. The state capital is Maracaibo. As of the 2011 census, it has a population of 3,704,404, the largest population among Venezuela's states. It ...

(Rincón, 2011) ** Quebrada Ocando,

Falcón State ) , anthem = , image_map = Falcon in Venezuela.svg , map_alt = , map_caption = Location within Venezuela , pushpin_map = , pushpin_map_alt = , pushpin_mapsiz ...

(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 Lara State ( es, Estado Lara, ) is one of the 23 states of Venezuela. The state capital is Barquisimeto. Lara State covers a total surface area of and, in 2015, had a census population of 2,019,211. Toponymy The state is named after a notable ...

(Karsten, 1886) ** San Miguel, Lara Sate (Van Frank, 1957) ** El Tocuyo, Lara State ** El Breal de Orocual,

Monagas State ) , anthem = '' Himno del Estado Monagas'' , image_map = Monagas in Venezuela.svg , map_alt = , map_caption = Location within Venezuela , pushpin_map = , pushpin_m ...

(Rincón ''et al''., 2009) *

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

** Juruá River,

Acre State Acre () is a state located in the west of the North Region of Brazil and the Amazonia Legal. Located in the westernmost part of the country, at a two-hour time difference from Brasília, Acre is bordered clockwise by the Brazilian states of Am ...

(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). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

** Cara Cara,

Beni Department Beni (), sometimes El Beni, is a northeastern 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 sq mi), and it was cre ...

( Hoffstetter, 1968) *

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

** 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 surf ...

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 (São Paulo)'' 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