Meet Arizona’s State Dinosaur the Sonorasaurus!
Only 12 states in the country have designated a state dinosaur, and Arizona is one of them. Our state dinosaur is the Sonorasaurus, a long‑necked giant that once roamed a very different version of the desert we know today. This dinosaur wasn’t discovered until just a few decades ago, and it didn’t become our official state dinosaur until fairly recently! Here's what we know about it!
Sonorasaurus
The Sonorasaurus is easily mistaken for a Brachiosaurus thanks to its towering neck and overall build, but it wasn’t nearly as massive. The Sonorasaurus was about half the size, weighing around 84,000 pounds and standing roughly 27 feet tall.
It lived between 112 and 93 million years ago, during the mid‑Cretaceous period. Back then, Arizona wasn’t a dry basin full of cacti and insects. It was a region shaped by wetlands, seasonal rainfall, and tall, lush vegetation. The Sonorasaurus would have moved through this greener landscape, feeding on abundant plant life and using its long neck to reach growth other dinosaurs couldn’t.
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The Discovery
The Sonorasaurus was discovered in 1994 by University of Arizona mathematician and geologist Richard Thompson. According to the Arizona State Senate, the fossils were discovered in the Whetstone Mountains of Cochise/Graham County. They were embedded in steep, rocky terrain, making excavation slow and challenging. Once studied, the bones revealed a new species of sauropod.
It was given the name Sonora-saurus due to its close ties to the Sonoran Desert and surrounding regions. Today, you can see Sonorasaurus fossils at the Arizona‑Sonora Desert Museum in Tucson, where parts of the original find are preserved and displayed.
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The State Dinosaur
The Sonorasaurus is formally recognized as the only described and named dinosaur species from Arizona. However, its path to becoming a state symbol didn’t happen overnight. In 2018, nearly 2 decades after its discovery, Arizona passed a bill that now lives in State Bill 1517-532R, designating it as the state dinosaur.
As a dinosaur found only in southern Arizona, the Sonorasaurus gives our state a rare and personal link to the Cretaceous past. Its bones tell the story of an environment far different from the one we see today. With every new discovery, we learn just how dynamic and surprising Arizona’s ancient world really was.
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Gallery Credit: Val Davidson/TSM
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