Sonorasaurus is a genus of brachiosaurid dinosaur from the Early to Late Cretaceous (Albian to Cenomanian stages, around 112 to 93 million years ago).

Thompson had investigated a previously almost unexplored region, where fossils proved to be plentiful and directly accessible on the surface.

The curator of geology of the museum, David W. Thayer, thought it might be a therizinosaur, mistaking a tail chevron bone for the long hand claw typical of that group.

Ratkevich and Thayer then visited the displays in the American Museum of Natural History, concluding their find was rather dissimilar to the hadrosaurid skeletons shown there, so that it must represent a species new to science.

Ratkevich considered naming it "Chihuahuasaurus" but ultimately shied away from the comical contrast between the gigantic sauropod and the minute dog breed.

[9] Europasaurus Vouivria Brachiosaurus Giraffatitan Sonorasaurus Lusotitan Cedarosaurus Venenosaurus In Mannion et al. (2019) it is still described as a brachiosaurid.