| Named By: | Samuel Paul Welles in 1947 |
| Time Period: | Middle Triassic, 243 Ma |
| Location: | USA, Arizona - Moenkopi Formation |
| Size: | Most complete specimen estimated at around 3 meters long |
| Diet: | Carnivore |
| Fossil(s): | Two specimens, one of an almost complete individual that revealed the developed neural spines |
| Classification: | | Chordata | Reptilia | Rauisuchia | Paracrocodylomorpha | Poposauroidea | Ctenosauriscidae | |
Arizonasaurus was a ctenosauriscid archosaur from the Middle Triassic (243 million years ago). Arizonasaurus is found in the Middle Triassic Moenkopi Formation of northern Arizona. A fairly complete skeleton was found in 2002 by Sterling Nesbitt. The taxon has a large sailback formed by elongate neural spines of the vertebrae. The type species, Arizonasaurus babbitti, was named by Samuel Paul Welles in 1947.