English: Machaeroprosopus andersoni Mehl, 1922 - fossil reptile skull from the Triassic of New Mexico, USA. (FMNH UC396, Field Museum of Natural History, Chicago, Illinois, USA)

Prima facie, this fossil skull looks like it is a crocodilian - but it's not! This is a phytosaur. Phytosaurs and crocodilians are unrelated reptiles that have similar body plans - an excellent example of convergent evolution. Phytosaurs are an extinct group of reptiles known only from Upper Triassic rocks, possibly extending into the Lower Jurassic.

---

From museum signage: With their long snouts and sharp teeth, phytosaurs looked, and perhaps behaved, like today's crocodiles. But scientists know that crocodiles did not evolve from these Triassic reptiles, because of some key differences. For example, a phytosaur's nostrils are between its eyes. (See the bumps on these skulls?) A crocodile's nostrils are at the tip of its snout.

---

This is the holotype skull of Machaeroprosopus andersoni, a phytosaur from Triassic nonmarine rocks in New Mexico.

Classification: Animalia, Chordata, Vertebrata, Reptilia, Phytosauria, Phytosauridae or Parasuchidae

Stratigraphy: likely derived from the Bull Canyon Formation, Chinle Group/Dockum Group, Upper Triassic

Locality: Guadalupe County, eastern New Mexico, USA (likely from Bull Canyon in eastern Guadalupe County)

---

See info. at: en.wikipedia.org/wiki/Phytosaur and

en.wikipedia.org/wiki/Machaeroprosopus