Classification and descriptionEdit
The holotype specimen of Piatnitzkysaurus, PVL 4073, was collected during expeditions in 1977, 1982, 1983 at the Canadon Asfalto Formation in sediments that were deposited during the Callovian stages of the Jurassic period, approximately 164 to 161 million years ago. Once thought to be a basal carnosaur, it may instead be a megalosauroid. In total two partial skeletons are known (a fractured skull and parts of two postcranial skeletons, among which paratype MACN CH 895) and show that Piatnitzkysaurus was a relatively lightly built medium-sized bipedal carnivore that was around 4.3 metres (14 ft) long and around 450 kilograms (990 lb) in mass, though such estimates apply to the holotype, which is a subadult. It had robust arms and powerful hind legs with four toes on each foot. Its ischium is 423 millimetres (16.7 in) long. Its braincase resembles that of another megalosauroid, the megalosaurid Piveteausaurus from France. A general resemblance to the theropod Allosaurus was also noted by Benton (1992).
The type species, Piatnitzkysaurus floresi, was described by Jose Bonaparte in 1979.