Duonychus

Duonychus (meaning "two claws") is an extinct genus of therizinosaurid theropod dinosaurs that lived during the Late Cretaceous (Cenomanian to early Coniacian age) of what is now Mongolia. It is known from a partial skeleton, including several vertebrae, most of the forelimbs, and part of the pelvic girdle, found in outcrops of the Bayanshiree Formation. The remains were discovered in 2012 by the Mongolian Academy of Sciences and briefly mentioned in later conference abstracts. The genus contains a single species, Duonychus tsogtbaatari, which was formally described in 2025.

The hand of Duonychus only has two fingers, similar to tyrannosaurids, compared to the three commonly found in most theropods. This anatomical feature—in addition to its long, strongly curved claws—may have allowed Duonychus to efficiently grasp plant material to consume. The geological formation from which Duonychus is known has also yielded the therizinosaurs Enigmosaurus, Erlikosaurus, and Segnosaurus, in addition to many other dinosaurs.