Tenontosaurus

Tenontosaurus is a genus of medium- to large-sized ornithopod dinosaur. The genus is known from the late Aptian to Albian ages of the middle Cretaceousperiod sediments of western North America, dating between 115 to 108 million years ago.

The genus contains two species, Tenontosaurus tilletti and Tenontosaurus dossi. Many specimens of T. tilletti have been collected from several geological formations throughout western North America. T. dossi is known from only a handful of specimens collected from the Twin Mountains Formation of Parker County, Texas.