Therizinosaurus

Therizinosaurus ("scythe lizard") was a therizinosaurid dinosaur from the Late Cretaceous Period of Mongolia.

Description
The fossil remains of Therizinosaurus are incomplete, so it is difficult to reconstruct the dinosaur from this material alone. However, better fossils of other therizinosaurs are known, so it is possible to make inferences based on the remains of other genera. As such, Therizinosaurus likely had a small head and long neck set upon a heavy body and short legs. It may have reached lengths of 10 meters and may have weighed 5 tonnes.

The forelimbs of Therizinosaurus are known, and they may have reached a maximum length of nearly 3 meters. Their most noticeable feature was the three gigantic claws on each hand, which inspired the animal's name (which translates to "scythe lizard"). Each claw was a meter long or more, the longest known claws of any animal.

Classification
Therizinosaurus belongs to the family Therizinosauridae, which was originally created specifically for this genus. The cladogram below shows the position of Therizinosaurus within the family based on a 2007 study.

History
The claws of Therizinosaurus were first discovered in 1948 during a joint Soviet-Mongolian expedition in the Nemegt Formation. They were named and described in 1954 as Therizinosaurus cheloniformis by Russian paleontologist Evgeny Maleev, who thought they belonged to a large and aquatic turtle-like creature. In 1970 the claws were determined to belong to a type of theropod dinosaur, but because the remains were so incomplete it was impossible to tell exactly what kind of theropod it was.

However, more fossil remains were collected in the 1970s and 1980s, and related dinosaurs from China were discovered. It was also discovered that the dinosaurs of the segnosaurid family were in fact therizinosaurs, allowing paleontologists to more accurately reconstruct Therizinosaurus based on its newly determined close relatives.

Diet
Unlike many other groups of theropod dinosaur but similar to other therizinosaurids, Therizinosaurus was probably herbivorous.

In popular culture
The strange claws of Therizinosaurus were appealing to a wide audience, and since it has been more confidently reconstructed it has appeared in television documentaries such as Chased by Dinosaurs and video games such as Dino Crisis.