Erlikosaurus andrewsi

Erlikosaurus is known from a skull, its feet, and a humerus. The skull is complete and beautifully preserved, whereas the rest of the Therizinosaurs are almost devoid of skulls. Erlikosaurus provides a model for the other's reconstructions. The upper jaws sported a sort of toothless beak, and the teeth were located towards the anterior part of the skull. The lower jaw was curved downwards towards the tip, and was full of small sharp teeth.
Its name means "King of the Dead Reptile" (Erlik is The King of the Dead in Mongolian lore)

This is my favorite Therizinosaurid.