On April 10, 2018 Sonorasaurus Thompsoni became Arizona's official state dinosaur. The fossil bones of Sonorasaurus were first dug up by geology student Richard Thompson in November 1994 in the Sonoran Desert in southern Arizona.

The Sonoraurus, which is related to the Brachiosaurus, was estimated to have lived in the middle Cretaceous Period about 100 million years ago. It was believed to have been about 50 feet long and nearly 30 feet tall.