Hi, do you have any information about what was Poposaurus's biology, appearance or geographical range ?

Could Breviparopus have been the tallest animal who ever walked on earth ?

I think Adam Britton of one of the others may be able to give you a better answer than i could for poposaurs, so for the time being i will let that part go (if no one else answers it, I will come back to it).

As for Breviparopus, sauropod researcher Matt Wedel states that the often reported track size for Brevipaopus is greatly inflated. In reality, there are other much larger trackways. this particular critter is actually smaller than Diplodicus, so very unlikely to be either the tallest or longest animal.

The Broome sandstone in Australia and the Jura plateau in France both have sauropod tracks that approach 1.5 m in diameter, as compared to the 90 cm of Breviparopus.

Poposaurus is a Triassic reptile quite closely related to crocodilians, but very different in appearance. It was bipedal and relatively lightly built, with the hind limbs much longer than the forelimbs. In general body shape, Poposaurus was fairly similar to primitive theropods (predatory dinosaurs) such as Coelophysis, and in fact Poposaurus was at one time considered to be a theropod itself. Poposaurus was probably about 3-4 metres from nose to tail.

Poposaurus is known from Upper Triassic rocks in the western part of the United States. It was first discovered in the Popo Agie Formation of Wyoming, which I presume is the source of its name. Most of the known specimens are very fragmentary, although a relatively complete skeleton was found in Utah several years ago. This specimen has not yet been formally described, but a lot of new information about Poposaurus should become available soon.