science

Mixotoxodon

Mixotoxodon is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Mixotoxodon rather than just read about it. In short: 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 epoch, from 1,500,000–12,000 years ago. Taxonomy Mixotoxodon is known from a single species, M. larensis.

Key takeaways

Mixotoxodon belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Mixotoxodon to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Mixotoxodon from memory before moving on to harder problems.

Reference excerpt

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 epoch, from 1,500,000–12,000 years ago.

Taxonomy Mixotoxodon is known from a single species, M. larensis. 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.

Evolution Mixotodon first appeared in Central America in the Early Pleistocene, with Barranca del Sisimico locality in El Salvador (approx. 1.5 Ma), and the Bajo Barrantes site in Costa Rica, which may be as old as 2 Ma.

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.

Size Mixotoxodon was a rhino-sized animal, a 2012 study estimated a weight of up to 3.8 tonnes (4.2 short tons), which makes it the largest member of Notoungulata, though this may be an overestimate.

Paleoecology 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, US.

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 Harris County, Texas Mexico Hihuitlán, Michoacán La Estribera, Veracruz (Polaco et al., 2004) Guatemala Santa Amelia River, Petén Department (Woodburne, 1969) Honduras Yeroconte, Lempira department (Webb and Perrigo, 1984) Orillas del Humuya, Comayagua department El Salvador Tomayate, San Salvador department (Cisneros, 2005) Cuscatlán Formation, Barranca del Sisimico, San Vicente department Hormiguero, San Miguel department (Webb and Perrigo, 1984) Nicaragua El Bosque, Estelí department (Leidy, 1886) Costa Rica Bajo de los Barrantes, Alajuela province (Laurito, 1993; Valerio, 1939; Spencer et al., 1997) Panama Ocú, Herrera Province (Gazin, 1956) South America Colombia Rotinet Formation, Chívolo, Magdalena (De Porta 1959; Villarroel 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 Cara Cara, Beni Department (Hoffstetter, 1968) Argentina Dique Los Quiroga, Santiago del Estero

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

References

Bibliography and further reading

Arroyo-Cabrales, Joaquín; Polaco, Oscar J.; Johnson, Eileen; Ferrusquía-Villafranca, Ismael (1 February 2010). "A perspective on mammal biodiversity and zoogeography in the Late Pleistocene of México". Quaternary International. 212 (2). Elsevier: 187–197. Bibcode:2010QuInt.212..187A. doi:10.1016/j.quaint.2009.05.012. 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. Lundelius, E. L.; Bryant, V. M.; Mandel, R.; Thies, K. J.; Thoms, A. (January 2013). "The first occurrence of a toxodont (Mammalia, Notoungulata) in the United States". Journal of Vertebrate Paleontology. 33 (1): 229–232. Bibcode:2013JVPal..33..229L. doi:10.1080/02724634.2012.711405. hdl:1808/13587. S2CID 53601518. 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. ISBN 0-231-11013-8 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. Van Frank, R. 1957. A fossil collection from northern Venezuela. 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.

Illustrations

Worked examples

Example 1 — a first encounter with Mixotoxodon

Start with the simplest possible case. Write down what Mixotoxodon claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Mixotoxodon before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Mixotoxodon ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Mixotoxodon

In research: Mixotoxodon appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Mixotoxodon in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Mixotoxodon is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ensenadan, Fossil taxa described in 1957, Fossils of Argentina, so understanding it makes those chapters shorter.
In everyday life: Look for Mixotoxodon outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Mixotoxodon in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Mixotoxodon means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Mixotoxodon out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mixotoxodon in simple terms?

Why does Mixotoxodon matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Mixotoxodon?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Mixotoxodon.