1.18" (3 cm) Herrerasaurid? tooth. From the Chinle Formation found in Navajo County Arizona. From the Late Triassic about 205-215 million years old.  

The tooth's mesial serration count is 15 serrations per 5 millimeters. The distal serrations are 21 per 5 mm. The distal serrations only run 3/4 of the tooth and stop before the gum line. All known rauisuchid and phytosaur teeth have equal serrations count The tooth much is too big to be a Coelophysid. The serration shape matches dinosaur the best, the tooth is compressed also. Not much is known about the teeth of Chinle Formation dinosaurs, so I cannot say what species. Chindesaurus or Tawa are possibilities.