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Megahippus; Temporal range: 16.3–10.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N Barstovian to Late Clarendonian
	Megahippus mckennai fossils
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Perissodactyla
Family:	Equidae
Subfamily:	†Anchitheriinae
Genus:	†Megahippus; McGrew, 1938
Species
	M. matthewi; M. mckennai;

Megahippus is an extinct genus of large Anchitheriine horses found throughout the southern portion of the United States during the middle Miocene. The animal represents one of the latest low-crowned horses, overlapping in time with more derived high-crowned horses.^[1]

Description

Dentition

Though generally similar to other genera within the subfamily, Megahippus is unique in the presence of a well defined ridge across the inner edge of the premolars 1-3 along with the presence of large, frontward-facing lower incisors.^[2] Unlike the incisors of other anchitheriines like Hypohippus, they would have been large and high-crowned.Between the two species, there is evidence of a trend of the animal's premolars shrinking overtime with them being larger proportionally in M. mckennai.^[3] Both Megahippus and Hypohippus show a general trend in the increase in frequency of conchets in their upper cheek teeth potentially due to the segregation of the section when compared to the earlier Anchitherium.^[4]

Crania

Megahippus is generally comparable with other genera in the subfamily, having a short premaxilla that constricts before the first premolar. The infra-orbital fossa is located about the P4 with the facial fossa positioned above and behind the infra-orbital fossa. The placement of the facial fossa more similar to the more basal Archaeohippus than the closely related Hypohippus.^[3]

Postcrania

The limb morphology of Megahippus is similar to those seen in living equines, having adaptations towards the restricted movement of the fetlock. Thought this seems to be a convergent adaption related to the support of larger body masses. The ungual of larger anchitheriins like Megahippus was also similar to Equus which would have given the animal a more rounded phalanx then smaller smaller genera.^[5]^[6] Unlike modern horses, the feet of Megahippus and other anchitheriins were tridactyl.^[7]The estimated body masses of the species of the genus are 194.9 kg for M. mckennai and 266.2 kg for M. matthewi.^[8]

Paleobiology

Based on wear and morphology seen in the incisors of Megahippus, this animal was a more specialized browser than other genera.^[9]During the time that the animal lived, the number of equid species in North America had massively decreased with only a few species being found throughout the continent and these species not being many numerous in their ecosystems.^[10]