Dinohippus Tooth-Nebraska 001

Taxa: Dinohippus sp.

Geology: Ogallala formation

Age: Pliocene

Locality: Texas County, Oklahoma

Size: 1.3"x1"x0.6" or 3.4x2.6x1.6 cm

 No repairs or restorations

Dinohippus

Dinohippus is an extinct genus of large, single-toed equid that flourished throughout North America from the late Miocene through the Pliocene epochs, spanning roughly 12 to 2 million years ago. Meaning "terrible horse," it was a heavily built grazer that stood as one of the most widespread and successful horses of its time. Paleontologists consider Dinohippus to be the closest evolutionary precursor and direct ancestor to the modern genus Equus (which includes modern horses, zebras, and donkeys), notably exhibiting the earliest known development of the "stay apparatus"—a specialized tendon and ligament system that allows modern horses to stand effortlessly for long periods without muscle fatigue.

Ogallala Formation

The Ogallala Formation is a vast, continental geologic deposit stretching across the central High Plains of the United States, from South Dakota down to Texas. Laid down primarily during the Miocene and early Pliocene epochs, it consists of gravel, sand, silt, and clay eroded from the rising Rocky Mountains and spread eastward by a network of braided streams and rivers. Interbedded with occasional volcanic ash falls and hardened caliche layers, this thick blanket of sediment forms the primary geological host for the Ogallala Aquifer, one of the world's largest underground freshwater reservoirs that sustains the vital agricultural economy of the American Great Plains.