Horse Jaw Section | South Dakota seam agate Location: Hawthorn Formation

Location: Hawthorn Formation

Due to the size of this specimen

Dinosaurs to Dodos: An Encyclopedia of Extinct Animals

Family Physeteridae

Its head shield (cephalon) is rimmed with strong spines

Horse Jaw Section | South Dakota seam agate Location: Hawthorn FormationMesohippus sp. Oligocene (33 30 MYO) Brule Formation White River Badlands South Dakota Specimen approx. size: 1. 25" x 1" x 0. 5" Mesohippus is a genus of extinct early horse that lived during the late Eocene to early Oligocene epochs, approximately 37 to 30 million years ago. Its fossils are primarily found in North America, particularly in the White River Formation of the western United States. As a transitional form in equid evolution, Mesohippus