Name Meaning: Plant Reptile
Geologic Era: Late Triassic
Location Discovered: Chinle formation, Arizona
Estimated Range: Near global
Extinction Date: Late Triassic
These are scutes (dermal armor) from a phytosaur. Unfortunately, there are possibly 11 phytosaurs known from the Chinle formation, so making an identification beyond “phytosaur” is next to impossible. The scute was cracked into two pieces, but is fairly typical of the dermal armor associated with these types of animals.
Phytosaurs are superficially similar to modern alligators and crocodiles, but with a few key differences. First, the nostrils on a phytosaur are close to the eyes. On a modern crocodilian, the nostrils are placed close to the end of the snout. This skull structure would have allowed a phytosaur to remain almost completely submerged in water and near invisible until prey came along. Having nostrils elevated and near the eyes would also allow the phytosaur to breath while mostly underwater. Second, the ankles of phytosaurs have a much more primitive structure than crocodiles. Another possible difference is the lack of a bony palate in phytosaurs (like modern crocodiles have), however, it is also possible that phytosaurs did have a fleshy palate, which would not fossilize. Having a palate would allow for breathing even if the mouth was underwater.
The reason for the meaning of the name “plant reptile” for an animal that quite obviously ate meat is that when phytosaur remains were first discovered, it was thought they came from a plant-eating animal. Later remains (particularly of skulls) showed this was not the case, but the name had already been given. A phytosaurs skull structure often gives hints as to its diet. Phytosaurs with slender snouts were probably eating fish or similar small, fast animals. Phytosaurs with broad, heavy jaws were probably eating larger, more heavily muscled land animals.
Skeleton: By Piotrus, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6395660
Smilosuchus: By Petrified Forest from Petrified Forest, USA – Smilosuchus adamanensisUploaded by FunkMonk, Public Domain, https://commons.wikimedia.org/w/index.php?curid=25182005