An 80-million-year-old tail bone discovered on a small island off the coast of British Columbia provides the clearest evidence yet that ostrich-like dinosaurs once roamed North America's Pacific coastline, researchers have announced.
Discovery on Denman Island
The fossil, an isolated caudal vertebra, was found on Denman Island and identified as belonging to an indeterminate ornithomimosaur. These fast-running, bird-like theropod dinosaurs lived during the Cretaceous period, from 145 million to 66 million years ago. They had small heads, slender bodies, toothless beaks, and long legs and necks, resembling modern-day ostriches.
Initially, researchers could not pinpoint the exact species, according to a study published in the journal FACETS. To overcome this, they performed CT scans of the fossil to create a 3D model, which they compared to tail bones of complete ornithomimosaur and tyrannosaur skeletons held in various museums. The comparison revealed that the fossil most closely resembled the ornithomimosaur tail bone.
Likely the 10th Caudal Vertebra
Researchers suspect the bone is likely the 10th caudal vertebra of a two-legged ornithomimosaur. They believe the bone may have been deposited on the island by a floating carcass, carried by waves, or transported by another scavenging dinosaur.
“How exactly the bone came to be deposited in this location is unknown but some possibilities include disarticulation from a floating carcass, transport from a carcass along the shoreline via wave action or turbidity current, or transport via scavenging,” the study authors wrote. “All of this evidence suggests the ornithomimosaur represented by the fossil was living on the western margin of North America.”
Researchers noted that determining how different this dinosaur was from those found elsewhere in North America “can only be answered with additional fossil discoveries.”
