Poposaurus fossil map
Where fossils of Poposaurus have been found, shown on the Earth as it looked about 215 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 215 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Crocodile relatives |
|---|---|
| Lived | 237–201.4 million years ago (Carnian to Rhaetian) |
| Periods | Triassic |
| Named by | Mehl 1915 |
| Fossil records | 20 occurrences at 17 locations (PBDB) |
| Found in | United States |
| Rock formations | Chinle, Colorado City, Tecovas, Popo Agie |
About Poposaurus
Poposaurus is an extinct genus of pseudosuchian archosaur from the Late Triassic of the southwestern and eastern United States. It belongs to the clade Poposauroidea, an unusual group of Triassic pseudosuchians that includes sail-backed, beaked, and aquatic forms. Fossils have been found in Wyoming, Utah, Arizona, Texas, and Virginia. Except for the skull, most parts of the skeleton are known. The type species, P. gracilis, was described and named by Maurice Goldsmith Mehl in 1915. A second species, P. langstoni, was originally the type species of the genus Lythrosuchus. Since it was first described, Poposaurus has been variously classified as a dinosaur, a phytosaur, and a "rauisuchian".
Like theropod dinosaurs, Poposaurus was an obligate biped, meaning that it walked on two legs rather than four. However, as a pseudosuchian, it is more closely related to living crocodilians than to dinosaurs. Poposaurus is thought to have evolved this form of locomotion independently, possibly from early archosaurs' ability to high walk.
Text in “About” is quoted from the Wikipedia article Poposaurus (revision 1360990310), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 23 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q135726.
