Dinosaurs have been around for the last 243 million years.
Arizona’s earliest known dinosaurs also appeared during the Triassic. Dinosaur fossils are found the in area around Holbrook, in the same area and time period as the Petrified Forest was living. The oldest fossils are of Chindesaurus bryansmalli, from 213-210 million years ago.
The Cretaceous sauropod Sonorasaurus lived in southern Arizona, and has been named the state dinosaur. It grew to over 45 feet long, and was a relative of the Brachiosaurus. Only the partial remains of one individual have been found.
Two dinosaurs that did not live in Arizona are Tyrannosaurus and Triceratops. Both are not found this far south in North America.