''Diadiaphorus'' 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 ...

mammal from the

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

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 ...

( Ituzaingó, Pinturas, Chiquimil and

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 ...

s) and Bolivia ( Nazareno Formation), South America.

Description

''Diadiaphorus'' closely resembled a

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 ...

, but was only around in body length with a weight , similar to a modern

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticated ...

.D. Patterson, Bruce (2012) ''Bones, Clones, and Biomes: The History and Geography of Recent Neotropical Mammals'' p.92 It had three toes, only one of which touched the ground. This toe had a large

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 ...

; the two outer toes were rudimentary, much like those of early horses such as ''

Merychippus ''Merychippus'' is an extinct proto-horse of the family Equidae that was endemic to North America during the Miocene, 15.97–5.33 million years ago. It had three toes on each foot and is the first horse known to have grazed. Discovery and nami ...

''. Unlike horses, however, ''Diadiaphorus'' lacked fused limb bones. Its

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, th ...

was short and had a relatively large brain cavity. Judging from its low

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 ...

, ''Diadiaphorus'' ate soft vegetation, such as leaves.

References

Proterotheriids Miocene mammals of South America Huayquerian Chasicoan Mayoan Laventan Colloncuran Friasian Santacrucian Neogene Argentina Fossils of Argentina Ituzaingó Formation Neogene Bolivia Fossils of Bolivia Fossil taxa described in 1887 Taxa named by Florentino Ameghino Prehistoric placental genera Austral or Magallanes Basin Santa Cruz Formation {{paleo-mammal-stub