Poposaurus gracilis

Late Triassic of southwestern USA. Discovered in 1904 and described in 1915.

Poposaurus almost certainly was bipedal, considering its short forelimbs. It was a pseudosuchian that was closely related to crocodiles. Poposaurus may have been around 100kg in body mass, but was long (4m) and not tall (~1m) due to the length of the tail (half of the total body length). Poposaurus is fascinating because, like a few other pseudosuchians, it showed traits such as bipedalism that were convergent with those in early dinosaurs, but had differences such as body armour and a robust ankle joint.

Artistic interpretation of Poposaurus by John Conway