Postosuchus: Top Triassic Predator

Postosuchos was a large archosaur (a family that includes modern day crocodiles as well as dinosaurs) that lived during the late Triassic Period. It was not a dinosaur itself, and was more related to crocodiles in both general appearance and morphology. Fossils of postosuchus have been unearthed in the Petrified Forest in Arizona.

This Triassic archosaur was undoubtedly a carnivore, and was among the largest on earth at the time it lived, around 200 million years ago. It had a long, crocodile-shaped body with a thick skull and a long, beefy tail. Adult postosuchus could reach lengths of twenty feet and a height of two meters. Unlike most predatory dinosaurs that would follow, postosuchus moved about on four legs instead of two. Due to the length of its legs and long, flat body, it is unlikely that it could have balanced on two legs for longer than a few moments. They perhaps could rear up on their hind legs briefly during a confrontation in order to seem larger than they were (although they were quite large to begin with). The legs of postosuchus are probably its most curious feature. Although it is related to crocodiles, this Triassic predator was adapted for life on land and had columnar legs to support its weight. These legs were positioned undearneath the body instead of bent out to the side like crocodiles or lizards. This means that postosuchos had an upright rather than a sprawling gait, which could have allowed it to conceivably run. However, due to its large size and still relatively short legs, it is up to debate whether postosuchus was a fleet-footed predator.

Postosuchus was likely at the top of the terrestrial Triassic food chain due to its size. Nothing was large enough to threaten it, and it also boasted impressive defenses such as armored plates on its back. Its large mouth full of dagger-like teeth would have made a menacing weapon capable of bringing down very large prey. Large herbivorous synapsids around at the time such as placerias could have fallen victim to this giant archosaur. Since there were a number of large, slow-moving herbivores around at this point in the Triassic scrublands, postosuchus would have profited being as large as it was. However, its dominance was short lived. Early dinosaurs that were confined to the shadows of postosuchus' world began to evolve into the top predators of the time. By the late Triassic and early Jurassic, the competition as top predator had exploded and postosuchus would be the loser.