''Thoatherium'' (meaning "active swift-beast") is an extinct genus of

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 ...

mammals from the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

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 of the genus have been found in the

Santa Cruz Formation The Santa Cruz Formation is a geological formation in the Magallanes/Austral Basin in southern Patagonia in Argentina and in adjacent areas of Chile. It dates to the late Early Miocene epoch, and is contemporaneous with eponymous Santacrucian ...

.''Thoatherium''
at Fossilworks.org

Description

With a length of , the

gazelle A gazelle is one of many antelope species in the genus ''Gazella'' . This article also deals with the seven species included in two further genera, '' Eudorcas'' and '' Nanger'', which were formerly considered subgenera of ''Gazella''. A third ...

-like ''Thoatherium'' was a small representative of the order Litopterna. Judging from its long legs, it was a fast runner. ''Thoatherium'' had remarkably reduced toes; only one

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 yea ...

-like

hoof The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rum ...

remained. ''Thoatherium'' even lacked splint bones, which are remnants of the second and fourth toe found in modern horses. Judging from its generalised, brachydont teeth, ''Thoatherium'' fed on soft leaves rather than on tough grasses.Darin A. Croft, ''Horned Armadillos and Rafting Monkeys: The Fascinating Fossil Mammals of South America'', Indiana University Press, 29/08/2016

References

Proterotheriids Burdigalian life Miocene mammals of South America Santacrucian Neogene Argentina Fossils of Argentina Fossil taxa described in 1887 Taxa named by Florentino Ameghino Prehistoric placental genera {{paleo-mammal-stub