Therizinosaurus lived in the Late Cretaceous Period 77-65.5 Million Years Ago, and was one of the last and largest representatives of its unique group, the Therizinosauria. Its fossils were first discovered in Mongolia and they were originally thought to be ribs belonging to a turtle-like reptile (hence the species name, T. cheloniformis — "turtle-formed"). It is known only from a few bones, including gigantic hand claws, from which it gets its name. It is speculated Therizinosaurus may have had feathers like others of its group. Due to is large claws it was originaly thought to be a carnivore until it was realized that it shared more in common with Ornithomimids than with any other dinosaur.