Known from two fragmentary skeletons, Piatnitzkysaurus was a medium size theropod from the Middle Jurassic of Argentina. Middle Jurassic theropods remains are scanty and Piatnitzkysaurus is the best known of the 3 theropods from that age found in the the southern hemisphere (the other two being Ozraptor from Australia and Condorraptor from Argentina). Its affinities are unclear, some authors assigning it to the Allosauridae, others to the Megalosauridae.