Adasaurus ( ; meaning "Ada lizard") is a genus of dromaeosaurid dinosaur that lived in Asia during the Late Cretaceous period about 70 million years ago. The genus is known from two partial specimens found in the Nemegt Formation of Mongolia that were partially described in 1983 by the paleontologist Rinchen Barsbold. Adasaurus was a large dromaeosaurid that was about long weighing . Unlike other dromaeosaurids, Adasaurus developed a rather small and blunt sickle claw that likely had a reduced use, and a recurved lacrimal bone; this latter trait is also shared with Austroraptor. Though reduced, the sickle claw retained the characteristic rounded articulation of most dromaeosaurids. Adasaurus was originally regarded as a dromaeosaurine by Barsbold, a group that includes robust dromaeosaurs with deep jaws. Revisions made to the specimens have showed that this dromaeosaurid belongs to the Velociraptorinae which is composed of more lightly built animals like Velociraptor. History of discovery Adasaurus was first figured in 1977 by the Mongolian paleontologist Rinchen Barsbold on a pelvic comparison with other theropods, but it would remain as an informally named taxon until a proper description. In 1983, Barsbold published a large comparative revision of the known Mongolian theropod taxa at the time where he formally named Adasaurus and the type species A. mongoliensis, which was based on two partial specimens. The generic name, Adasaurus, is taken from the Mongolian word (, meaning evil spirit), and the Greek word (, meaning lizard). The specific name for the single species, mongoliensis, refers to the country of discovery Mongolia. Barsbold briefly described Adasaurus as a dromaeosaurid and noted that this new taxon possessed a notably reduced second pedal ungual. Given that this trait contrasted to the large, sharply-developed ungual of most members, Barsbold listed it as a unique character for Adasaurus. However, the authenticity of this unusual reduction was disputed in 2010 by Phil Senter, who claimed that the supposed ungual did not pertain to the specimen. Nevertheless, in the revised diagnosis conducted by Turner and colleagues in 2012, this character is still considered as authentic, which has been widely followed by other authors. Adasaurus is known from the holotype MPC-D 100/20, which represents an adult individual comprising a partial skull missing its anterior region, the right scapulocoracoid and a sternal plate, 8 cervical vertebrae, 11 partial dorsal vertebrae, the sacrum, 7 caudal vertebrae, partial hindlimbs with the right foot, and a nearly complete