1.1" Phytosaur tooth. Very thick, and serrated. From the Chinle Formation found in Navajo County Arizona. From the Late Triassic about 205-215 million years old. 

Phytosaurs are a close relative of dinosaurs and looked remarkably like modern crocodiles. However, Crocodiles are not descended from Phytosaurs. Phytosaur noses were on top their head closer to their eyes unlike crocodiles whose nose is on the tip of their snout. Most Phytosaur teeth were also heavily serrated, a trait most crocodile teeth do not have.