Therizinosaurus was the largest member of the therizinosaur family. They were 30-36 feet long and weighed over 3-4 tons. Like many species, no complete skeleton is known, as the only fossils found so far are the arms and claws. The arms alone were over 10 feet long and the claws were a staggering 3 feet! Therizinosaurus lived about 65-75 million years ago in Asia.