Patagonykus is a genus of alvarezsauroid theropod dinosaur from the Upper Cretaceous of Argentina. It was discovered in exposures of the Portezuelo Formation (Turonian-Coniacian) of the Rio Neuquén Subgroup in the Neuquén Basin, Neuquén Province. The holotype consists of an incomplete but well-preserved skeleton, lacking a skull, but including many vertebrae, the coracoids, a partial forelimb, pelvic girdle, and hindlimbs. Patagonykus has been classed with the Alvarezsauridae, a family which includes such taxa as the Mongolian Mononykus and the also Argentinian Alvarezsaurus. In 2010, Gregory S. Paul estimated its length at 1 meter (3.3 ft) and its weight at 3.5 kilograms (7.7 lb).