Piatnitzkysaurus (/ˌpiːətnɪtskiːˈsɔːrəs/ pee-ət-NITS-kee-SOR-əs; meaning "Piatnitzky's lizard") is a genus of tetanuran theropod dinosaur that lived approximately 179 to 177 million years ago during the lower part of the Jurassic Period in what is now Argentina. Piatnitzkysaurus was a moderately large, lightly built, bipedal, ground-dwelling carnivore that could grow up to 6.6 m (21.7 ft) long.