Therizinosaurus, (commonly called "Claws" in the specials) lived in the Late Cretaceous Period and was one of the last and largest representatives of its unique group, the Therizinosauria.
Therizinosaurus was 13 metres long, 7 metres tall and weighs up to 8 tonnes. 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, as is thought for other Therizinosaurs, and as is in the growing number of Cretaceous Theropoda that are now being depicted as feathered.
Therizinosaurus didn't feature in the main Walking with Dinosaurs series.
Therizinosaurus was featured in a Walking With Dinosaurs Special - Chased By Dinosaurs, where it was referred to as "Claws". In the episode, it fought the Asian Tyrannosaurid Tarbosaurus. The Tarbosaurus tried to bite the Therizinosaurus on its long neck, but the Therizinosaurus slashed the Tarbosaurus on the side of the face with its huge claws. Tarbosaurus then retreated to prevent further injury.