Piatnitzkysaurus

Type Species: Piatnitzkysaurus floresi

Classification: Dinosauria – Saurischia – Theropoda – Allosauroidea 

Time Period: Middle Jurassic

Location: South America (Argentina)

Diet: Carnivore 

Piatnitzkysaurus was a medium-sized, lightly-built theropod that grew up to twenty-one feet in length. It was the apex predator in its South American environment; it likely hunted smaller dinosaurs, and it may hunted in packs to bring down large sauropods such as Patagosaurus. It probably wasn’t aversive to scavenging the carcasses of dead dinosaurs or marine reptiles that washed onto the beach. Piatnitzkysaurus was discovered in the Canadon Asfalto Formation in Argentina, which gives us an exquisite snapshot of the Callovian stage of the Middle Jurassic. One researcher noted that ‘the fossil record of this formation represents the most completely known biota from the continental Middle to Late Jurassic of the Southern Hemisphere and one of the most complete of the entire world.’ The assemblage of fossils allows us to get a pretty accurate picture of what the environment was like back then. During the late Middle Jurassic and early Late Jurassic, the plants of this area were largely conifers, though ferns are also abundant. Directly beneath the formation is a layer of ash, indicating a nearby volcano (not surprising, given the intense amount of volcanic activity in the Jurassic due to the splitting of the supercontinents). Terrestrial organisms in this lush, tropical environment include the primitive frog Notobatrachus, the turtle Condorchelys, the lizard-like rhynchocephalian Sphenocondor, and a numerous small, early mammals such as Argentoconodon, Asfaltomylos, and Henosferus. The largest creatures were, of course, the dinosaurs. These include the sauropods Patagosaurus and Volkheimeria; the herbivorous heterodont Manidens is also represented, and scientists theorize that it was an arboreal (tree-dwelling) dinosaur due to its feet, which were structured like those of tree-perching birds. Other theropods of the environment included Condorraptor, the abelisaur Eoabelisaurus, and the early allosaur Asfaltovenator. The small pterosaur Allkaruen flitted about the trees above the heads of these terrestrial dinosaurs.