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.^[1]

Thoatherium Temporal range: Early Miocene (Santacrucian) ~17.5–16.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
1901 T. minusculum skeletal illustration
1913 T. minusculum illustration, by Charles R. Knight.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Litopterna
Family:	†Proterotheriidae
Subfamily:	†Proterotheriinae
Genus:	†Thoatherium Ameghino 1887
Type species
†Thoatherium minusculum Ameghino, 1887
Species
T. bilobatum Ameghino 1904 T. karaikense Ameghino 1904 T. minusculum Ameghino 1887 T. rhabdodon Ameghino 1894 T. velatum Ameghino 1904
Synonyms
Genus synonymy Oreomeryx Mercerat, 1891 Rhagodon Ameghino, 1891 Diaphragmodon Mercerat, 1893 T. minisculum Proterotherium cavum Ameghino, 1887 Rhagodon gracilis Ameghino, 1891 Thoatherium crepidatum Ameghino, 1891 Anisolophus burmeisteri Mercerat, 1891 Oreomeryx proprius Mercerat, 1891 Oreomyx superbus Mercerat, 1891 Diaphragmodon cavum (Ameghino, 1887) Mercerat, 1893 Diaphragmodon burmeisteri (Mercerat, 1891) Mercerat, 1893

Description

T. minusculum (=T. crepidatum) skull cast. At the AMNH.

With a length of 70 centimetres (2.3 ft), the gazelle-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-like hoof 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.^[2][3]

T. minisculum right foot, showing the presence of only a single toe.