Fossil evidence has been found for all of the following in Petrified Forest.
Drepanosaurs, tanystropheids, and Vancleavea
Drepanosaurs are bizarre reptiles are generally small and are known from exquisite specimens from the Triassic limestone quarries in Europe. They may have behaved much like modern chameleons or squirrels;they generally had large, hooked claws on their hands and prehensile, grasping tails. At the park, drepanosaurs are known from these claws and their vertebrae.
Tanystropheids are also small reptiles, but they tend to have extraordinarily long necks that are longer than the rest of the body. Vertebrae from these animals are very recognizable, and we have only recently been finding them in the field.