''Chasicotherium'' 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 ...

of a large

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 ...

mammal known originally from a partial

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

and

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

discovered in the

Arroyo Chasicó Formation Arroyo often refers to: * Arroyo (creek), an intermittently dry creek Arroyo may also refer to: People * Arroyo (surname) Places United States ;California * Arroyo Burro Beach, a public beach park in Santa Barbara County, California * Arroyo ...

, in the stream of Party of Villarino,

Buenos Aires Buenos Aires ( or ; ), officially the Autonomous City of Buenos Aires ( es, link=no, Ciudad Autónoma de Buenos Aires), is the capital and primate city of Argentina. The city is located on the western shore of the Río de la Plata, on South ...

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 ...

. The sediments in which the animal was discovered dates to 10 to 9 million years (

Chasicoan The Chasicoan ( es, Chasiquense or es, Chasicoense) age is a period of geologic time from 10–9 Ma within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Mayoan and ...

). It is known only from the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, ''C. rothi''. Its weight was approximately , being the largest and most recent member of the family

Homalodotheriidae Homalodotheriidae is an extinct family comprising four genera of notoungulate mammals known from the Late Eocene (Tinguirirican) through Late Miocene (Chasicoan) of Argentina and Chile in South America South America is a continent enti ...

. It was a large herbivore of the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Pampas The Pampas (from the qu, pampa, meaning "plain") are fertile South American low grasslands that cover more than and include the Argentine provinces of Buenos Aires, La Pampa, Santa Fe, Entre Ríos, and Córdoba; all of Uruguay; and Brazil ...

, closely related to ''

Homalodotherium ''Homalodotherium'' is an extinct genus of notoungulate mammals native to South America. Fossils of ''Homalodotherium'' have been found in the Middle Miocene (Friasian in the SALMA classification) Santa Cruz Formation of Argentina and the Río ...

'', which also shares the reduced dental formula of the short

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...

.Bocchino de Ringuelet, A. (2013). Estudio del género ''Chasicotherium'' Cabrera y Kraglievich 1931 (Notoungulata - Homaldotheriidae). ''Ameghiniana'', 1(1-2). http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/1083

References

{{Taxonbar, from=Q5087293 Toxodonts Miocene mammals of South America Neogene Argentina Fossils of Argentina Fossil taxa described in 1931 Taxa named by Florentino Ameghino Prehistoric placental genera