An 80-million-year-old tail found on a small island off the coast of British Columbia was the clearest evidence yet that ostrich-like dinosaurs once roamed North America’s Pacific coastline, researchers said.
These fast-running, bird-like theropod dinosaurs called ornithomimosaurs lived during the Cretaceous period from 145 million to 66 million years ago.
They had small heads, slender bodies, toothless beaks, as well as long legs and necks, which made them resemble modern-day ostriches.
In a recent dig, researchers discovered an isolated caudal vertebra, or tail bone, on Denman Island, and identified it as “belonging to an indeterminate ornithomimosaur”.
Initially, according to a study published in the journal FACETS, researchers could not identify the specimen more precisely to pinpoint the exact species.
So, they did CT scans of the fossil to create a 3D model, which they compared to the tail bones of complete ornithomimosaur and tyrannosaur skeletons held in various museums.
This methodology revealed that the fossil most closely resembled the ornithomimosaur tail bone.
Researchers suspect it is likely the 10th bone of the caudal vertebra of a two-legged ornithomimosaur.
They suspect the bone was deposited on the Canadian island by a floating carcass, carried by waves or likely 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,” they wrote in the study.
“All of this evidence suggests the ornithomimosaur represented by the fossil was living on the western margin of North America.”
How different this dinosaur was from those found elsewhere in North America, researchers said, “can only be answered with additional fossil discoveries”.
