| Named By: | Jose Bonaparte in 1979 |
| Time Period: | Middle Jurassic, 166-164 Ma |
| Location: | Argentina - Canadon Asfalto Formation |
| Size: | About 4.3 meters long |
| Diet: | Carnivore |
| Fossil(s): | Two skulls and partial post cranial remains |
| Classification: | | Chordata | Reptilia | Dinosauria | Saurischia | Theropoda | Megalosauroidea | |
Piatnitzkysaurus ( PEE-at-nits-kee-SAW-ras) is an extinct genus of megalosauroid theropod dinosaur that lived approximately 166 to 164 million years ago during the middle 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 4.3 m (14.1 ft) long.