Thoatherium is an extinct genus of litoptern mammal.

With a length of 70 centimetres (2.3 ft), the gazelle

Gazelle

A gazelle is any of many antelope species in the genus Gazella, or formerly considered to belong to it. Six species are included in two genera, Eudorcas and Nanger, which were formerly considered subgenera...

-like Thoatherium was the smallest representative of the order Litopterna

Litopterna

Litopterna is an extinct order of fossil hoofed mammals from the Tertiary period that displays toe reduction. Three-toed, and even a one-toed horselike form developed....

. Judging from its long legs, it was a fast runner. Thoatherium had remarkably reduced toes; only one horse

Horse

The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

-like hoof

Claw

A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...

 remained. Thoatherium even lacked splint bones, which are remnants of the second and fourth toe found in modern horses. Judging from its generalised teeth, Thoatherium fed on soft leaves rather than on tough grasses.