pulling vegetation within reach rather than being used for active attack or defense because of their fragility, however, they may have had some role for intimidation. Its arms also were particularly resistant to stress, which suggests a robust use of these limbs. Therizinosaurus was a very tall animal, likely having a reduced competition over the foliage in its habitat and outmatching predators like Tarbosaurus. History of discovery In 1948, several Mongolian Paleontological expeditions organized by the USSR Academy of Sciences were conducted in the Nemegt Formation of the Gobi Desert, Southwestern Mongolia, with the main objective of new fossils findings. The expeditions unearthed numerous dinosaur and turtle fossil remains from the stratotype locality Nemegt (also known as Nemegt Valley), but the most notable elements collected were three partial manual unguals (claw bones) of considerable size. This set of unguals was found on a subdivision of the Nemegt locality designated as Quarry V near the skeleton of a large theropod, but also in association with other elements including a metacarpal fragment and several ribs fragments. It was labelled under the specimen number PIN 551-483 and later on, these fossils were described by the Russian paleontologist Evgeny Maleev in 1954 who used them to scientifically name the new genus and type species Therizinosaurus cheloniformis, becoming the holotype specimen. The generic name, Therizinosaurus, is derived from the Greek (, meaning scythe, reap or cut) and (, meaning lizard) in reference to the enormous manual unguals, and the specific name, cheloniformis, is taken from the Greek (, meaning turtle) and Latin formis as the remains were thought to belong to a turtle-like reptile. Maleev also coined a separate family for this new and enigmatic taxon: Therizinosauridae. Since little was known of Therizinosaurus at the time of the original description, Maleev thought PIN 551-483 belonged to a large, long turtle-like reptile that relied on its giant hand claws to harvest seaweed. Though it was not fully understood to what general kind of animal these fossils belonged, in 1970, the Russian paleontologist Anatoly K. Rozhdestvensky was one of the first authors to suggest that Therizinosaurus was a theropod and not a turtle. He made comparisons between Chilantaisaurus and the holotype unguals of Therizinosaurus to propose that the appendages actually came from a carnosaurian dinosaur, thereby interpreting Therizinosaurus as a theropod. Rozhdestvensky also illustrated the three holotypic manual unguals and re-identified the metacarpal fragment as a metatarsal