|1st Species||Poposaurus gracilis|
|2nd Species||Poposaurus langstoni|
|Time Range||228-208.5 mya|
|Location||United States of America|
|Name Meaning||Popo Agie reptile|
|Physical Dimensions||4 meters long|
Despite being a paracrocodylomorph, Poposaurus had a build very similar to the dinosaurs it was distantly related to, with a slender body, long hindlegs, moderately-sized arms, an extremely long tail, and a big head with large jaws. Its body would have been covered in scaly skin.
Poposaurus was a predator, preying on small dinosaurs, large anomodonts, cynodonts, and small crocodylomorphs. Its teeth had knife-like serrations from back to back, and were used to cut into the hides of large prey.
The most interesting thing about Poposaurus is its bipedal posture; back when it was discovered, its long legs and deep hip socket were believed to be similar to that of an early dinosaur such as Coelophysis (despite the fact that Poposaurus was later found out to be a paracrocodylomorph). Bipedal locomotion for Poposaurus was confirmed when more complete specimens were discovered and more accurate studies were made; this bipedal posture may have evolved from the "high walking" (walking with an erect posture) locomotion of modern crocodiles, which is believed to be ancestral to all archosaurs. Despite being similar in posture and diet to the large rauisuchid Postosuchus, Poposaurus occupied a different ecological niche. Due to its slender build and long tail, Poposaurus would have been a fast and agile runner, and would have lived the lifestyle as a pursuit predator (as opposed to Postosuchus' lifestyle of ambush predator).