Postosuchus was a large, 4-6 metre long, 3/4-1 tonne Rauischian Archosaur from the Late Triassic Period, with dagger-like teeth up to 7-8 cm long. It was the largest predator of the time, at least in the region of North America in which it is found The voracious Triassic terror (a South American 'big brother' of Postosuchus, called Fasolasuchus tenax, is known to have been an 8-11 metre long, 2 tonne giant, only surpassed by the largest Theropod Dinosaurs) afraid of nothing except another larger Postosuchus. It went extinct at the end of the Triassic, possibly because of competition from dinosaurs, its close Archosaurian cousins - though it should be noted that there was also a huge extinction event at the Triassic-Jurassic Period boundary, which killed off thousands of species of ancient reptiles and amphibians as well as others, so generally it could A female Postosuchus quenches her thirst in the Wet Season. It can be assumed that Postosuchus was just another casualty of this. What is certain, is that the crurotarsan archosaurs to which Postosuchus belongs, were formidable rivals to the Dinosauria, and their decline and later demise must have surely been to the benefit of the 'upstart' Dinosaurs.