A diminutive deinonychosaur (Dinosauria: Theropoda) from the Early Cretaceous of Oosh (Ovorkhangai, Mongolia)

We describe a new specimen of small maniraptoran theropod from the Early Cretaceous Oosh locality, Ovorkhangai province, central Mongolia. This exemplar ISMD-VP09 preserves a maxillary fragment, two teeth and partial appendicular elements. The strict consensus of a parsimony analysis of 68 coelurosaur taxa places this theropod within Deinonychosauria with an unresolved relationship with the other members of the clade. Support for this clade was based on two unambiguous synapomorphies: maxillary dentition with at least some teeth lacking denticles anteriorly, and ungual and penultimate pedal phalanx II highly modified for hyperextension, with ungual II being more strongly curved and substantially larger than that of digit III. The finding of a new small theropod specimen in the Oosh Formation adds to the deinonychosaur fossil record from the same beds, until now restricted to the dromaeosaurid Shanag ashile.