This is the well preserved and fully intact fossilized femur of a Dryosaurus altus, found in Emery County, Utah within the famous fossil-rich Morrison Formation spanning much of the Western United States. The Dryosaurus altus was a species of ornithopod living during the late Jurassic period. “Dryosaurus” means “oak lizard”, and “altus” references this herbivorous dinosaur’s relatively tall stature and agility.