In a striking find, two massive forelimb bones from a stegosaurid dinosaur have been confirmed as the largest ever discovered. These fossils, dug up in 1950 in Utah, reveal a dinosaur that could rival the giants of the Jurassic period.
These bones were found in the Uinta Basin, part of the renowned Morrison Formation. They’ve been displayed at the Utah Field House of Natural History, but their true significance was overlooked until recently. Paleontologist ReBecca Hunt-Foster and her team took a closer look and were amazed by what they found.
The key fossils include two humeri, which measure 70 and 74 centimeters, along with other bones from the right forelimb. Published research in the New Mexico Museum of Natural History and Science Bulletin shows these bones exceed the size of any previous stegosaurid finds. Typically, stegosaurids are thought to be medium-sized, but these bones challenge that notion. The next largest known specimen measures only 68 centimeters!
According to Hunt-Foster, the shape of the bones, especially the thick shafts and muscle attachment points, confirms they belong to a stegosaurid. They suggest a dinosaur much larger than the known Stegosaurus ungulatus, which reached about 7.5 meters and weighed around 5 tonnes. However, without more skeletal parts, we can’t definitively name this new giant.
Surprisingly, these bones were hidden for over 70 years. The Morrison Formation is known for its giant sauropods like Brachiosaurus and Diplodocus, so even oversized stegosaur bones didn’t catch much attention. Hunt-Foster believes the original cataloging was done by a geologist, not a dinosaur expert, leading to the long delay in recognizing their importance.
“Most of the bones seem to have been correctly identified originally, although one was thought to be a sauropod,” Hunt-Foster noted. “It’s possible the curator back then didn’t have a background in stegosaurs.”
One of the bones was mistaken for a sauropod, but a careful analysis unveiled features unique to stegosaurids. Most visitors to the museum likely didn’t realize they were seeing bones from a record-breaking dinosaur.
This revelation adds an exciting layer to our understanding of stegosaurids. Historically viewed as smaller creatures, these new findings suggest there might have been larger species roaming the Earth. As more discoveries arise, who knows what other surprises the past might hold?
