Mesoreodon

Mesoreodon is an extinct genus of terrestrial herbivore of the family Merycoidodontidae, subfamily Merycoidodontinae (the oreodonts), endemic to North America during the Whitneyan stage of the Oligocene-Miocene epochs (33—20.6 mya) existing for approximately 12.4 million years.^[1]

Mesoreodon Temporal range: Oligocene to early Miocene, 33–20.6 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Reconstructed M. floridensis skeleton, Florida Museum of Natural History
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Family:	†Merycoidodontidae
Subfamily:	†Merycoidodontinae
Genus:	†Mesoreodon Scott, 1893
Type species
†Mesoreodon chelonyx Scott, 1893
Species
M. chelonyx Scott, 1893 M. floridensis MacFadden & Morgan, 2003 M. minor Douglass, 1903

Taxonomy

Fossil skull of M. chelonyx, the type species

The following fossil species are known:^[2]

• M. chelonyx Scott, 1893 (type species) - Oligocene/Early Miocene (Arikareean) of the western United States (Idaho, Nebraska, Montana, Wyoming)
• M. floridensis MacFadden & Morgan, 2003 - Late Oligocene of Florida, US (Parachucla Formation)
• M. minor Douglass, 1903 - Oligocene/Early Miocene (Arikareean to Harrisonian) of the western United States (Oregon, Idaho, Nebraska, South Dakota, Montana, Wyoming)

Morphology

It was a large animal and ate the numerous low-growing plants and early grasses that sprung up on the plains of North America. It had a rather robust jaw, and like all oreodonts, sharp canine teeth.

Unlike many other oreodonts, who were restricted to certain habitats and places, Mesoreodon seemed to have been a cosmopolite. Fossils of Mesoreodon have been found in the Miocene deserts of California, the prairies of Nebraska, Wyoming, and South Dakota, southeastern Idaho, John Day Fossil Beds in Oregon, and Florida. In fact, Mesoreodon is the only Florida oreodont known from a complete skeleton, odd, since oreodonts had a continent-wide dominance until their extinction. They lived in all environments, and must have been very adaptable.

Mesoreodon had ossified vocal cords; the only other animal to have these in modern times is the howler monkey.^[3] Mesoreodon may have been a "screaming oreodont" using loud noises to intimidate its enemies and rivals.