Arizona’s Fort Crittenden Formation is a Late Cretaceous rock unit best known for fossil-bearing layers that preserve evidence of life near the end of the age of dinosaurs. Its recovered fossils show a varied vertebrate fauna, including dinosaur remains. Among the reported finds are tyrannosaurid material attributed to Gorgosaurus as well as teiid and anguid lizards. Together with other vertebrate fossils, these discoveries make the formation an important paleontological site for understanding the Late Cretaceous in the American Southwest.