Arizonasaurus was a ctenosauriscid archosaur from the Middle Triassic (240 million years ago). Arizonasaurus is found in the Middle Triassic Moenkopi Formation of northern Arizona. It has a large sailback formed by elongate neural spines of the vertebrae. The type specie is Arizonasaurus babbitti. It was around 6 meters ( 19.6 feet ) long.