Revueltosaurus callenderi Hunt 1989
Late Triassic
Bull Canyon Formation
Guadalupe County
New Mexico, USA

Fine 0.1 inch tooth. So small it must be a juvenile.

Revueltosaurus is a genus of pseudosuchian archosaur which makes it closely related to early crocodilians.  It’s known from the Late Triassic of different parts of North America.  It was once considered an early ornithischian dinosaur based on isolated teeth, but after skeletons were collected and studied, it was reclassified.