''Prolicaphrium'' 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 proterotheriid

litoptern Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until th ...

that lived during the Early Miocene, in what is now

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 ...

. Fossils have been found in the

Sarmiento Formation The Sarmiento Formation (Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid- ...

of Argentina.

Description

This animal may have been vaguely similar to a small

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...

, and, even if it is only known from incomplete fossils, it is possible to hypothesize on its appearance thanks to the comparison with its better-known relatives, such as ''

Thoatherium ''Thoatherium'' (meaning "active swift-beast") is an extinct genus of litoptern mammals from the Early Miocene of Argentina. Fossils of the genus have been found in the Santa Cruz Formation in Argentina.Proterotherium ''Proterotherium'' (meaning "first beast") is an extinct genus of litoptern mammal of the family Proterotheriidae that lived during the Late Miocene of Argentina and Chile. Fossils of this genus have been found in the Ituzaingó Formation of Arge ...

'' and ''

Diadiaphorus ''Diadiaphorus'' is an extinct genus of litoptern mammal from the Miocene of Argentina ( Ituzaingó, Pinturas, Chiquimil and Santa Cruz Formations) and Bolivia ( Nazareno Formation), South America. Description ''Diadiaphorus'' closely rese ...

''. Compared to the latter, ''Prolicaphrium'' was more basal, especially regarding its

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

: the six primary denticles were well developed and independent. The last molar had a reduced posterior lobe both in its external and internal parts. ''Prolicaphrium'' was also characterized by a skull with very elongated nasal bones pointing forward, to the contrary of the previously mentioned genera.

Classification

''Prolicaphrium'' is a member of the

Proterotheriidae Proterotheriidae is an extinction, extinct family of fossil ungulates from the Cenozoic era that displays toe reduction. Despite resembling primitive, small horses, they were only distantly related to them, and instead belonged to the native Sou ...

, a family of litopterns with a build vaguely evocative of small horses. The genus ''Prolicaphrium'' was first described in 1902 by

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especially ...

, based on fossil remains from Early Miocene terrains of

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...

, and it was considered to belong to an animal ancestral of the also Early Miocene genus ''

Licaphrium ''Anisolophus'' is an extinct genus of proterotheriid from the Early to Middle Miocene of Argentina. The genus was named by Burmeister in 1885 to accommodate the species ''Anchitherium australe'', which they had named earlier in 1879. Soria then ...

'' (now considered a synonym of ''

Anisolophus ''Anisolophus'' is an extinct genus of proterotheriid from the Early to Middle Miocene of Argentina. The genus was named by Burmeister in 1885 to accommodate the species ''Anchitherium australe'', which they had named earlier in 1879. Soria then ...

''. Ameghino described two species : the type species, ''Prolicaphrium specillatum'', and the better known ''P. spectabile''.A third species described by Ameghino, ''P. festinum'', was later attributed to a new genus, '' Licaphrops'' (a junior synonym of ''

Lambdaconus ''Lambdaconus'' is a genus of proterotheriid from the Late Oligocene to Early Miocene of Argentina. The type species is ''L. suinus'', named in 1897 by Ameghino, with referred species including ''L. lacerum'', named as ''Proterotherium ''Prot ...

''), while ''P. sanalfonensis'', initially described in 1997 and coming from the Middle Miocene of

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 ...

was attributed to the new genus ''

Mesolicaphrium ''Mesolicaphrium'' is a genus of extinct litoptern from the late middle Miocene of southern Colombia. It was named in 2020 by Andrew McGrath and colleagues, for the species previously classified as '' Prolicaphrium sanalfonensis'' from the La Vi ...

''.

References

*R. L. Cifelli and J. Guerrero Diaz. 1997. Litopterns. Vertebrate Paleontology in the Neotropics. The Miocene fauna of La Venta, Colombia 289–302 *Andrew J. McGrath; Federico Anaya; Darin A. Croft (2020). "New proterotheriids from the middle Miocene of Quebrada Honda, Bolivia, and body size and diversity trends in proterotheriid and macraucheniid litopterns (Mammalia)". Ameghiniana. in press. doi:10.5710/AMGH.03.03.2020.3268. {{Taxonbar, from=Q97183428 Proterotheriids Miocene mammals of South America Neogene Argentina Fossils of Argentina Colhuehuapian Fossil taxa described in 1902 Taxa named by Florentino Ameghino Prehistoric placental genera Golfo San Jorge Basin Sarmiento Formation