Ostrich-Like Dinosaur the Size of a Giraffe Found in Mississippi

by Taylor Cunningham
(Photo credit should read Thibaud MORITZ/AFP via Getty Images)

Scientists have identified fossilized remains that were recently found in the Eutaw Formation of Mississippi as the world’s fastest dinosaur—the ornithomimosaur.

Ornithomimosaurs are a group of bipedal dinosaurs, which walked on two legs. And they looked similar to modern-day ostriches.

“They generally have large eyes, long arms with relatively large clawed hands, long legs, a long tail, and either have small or no teeth,” Tom Cullen, an author of the study, told Newsweek. “The teeth are absent in later ornithomimosaurs with them having a keratinous beak to assist in processing food.”

The creature roamed the Northern Hemisphere between 145 million and 66 million years ago. And Cullen said that not only did they look like an ostrich, but they ate the same diet, “mostly herbivorous,” and they were extremely fast-moving, just like today’s birds, which can sustain speeds of 31 mph.

Ornithomimosaurs evolved over time. The earliest species was incredibly small. But over its millions of years on Earth, some grew to be massive in size.

“The smallest species, such as the 125-million-year-old Chinese species Hexing qingyi, were barely over a meter long, whereas the biggest one, the 72 million-year-old Deinocheirus mirificus from Mongolia, was a massive, hump-backed, giant-armed animal over 33 feet long!” explained Chase Brownstein, a research associate at the Stamford Museum and Nature Center.

The Discovery Helped Scientists Understand the Once-Hazy Evolution of the Bird-Like Dinosaur

The discovery has helped scientists gain a new understanding of the specific dinosaurs’ evolution. Until recently, they had very little few remains to study. Cullen added that we have “gaps” in our knowledge about them because their bones weren’t well-preserved.

The biggest gap in understanding is about the ornithomimosaurs that lived between 100 million and 83 million years ago.

“Prior to this time, we have a somewhat patchy record of ornithomimosaurs in North America, some of which were likely decently large,” Cullen said. “After this time gap we have a fairly rich record of ornithomimosaurs in western North America that are almost all fairly small-bodied. So we weren’t sure what this mid-point would look like.”

In a study published in PLoS One Cullen and his team analyzed femur bone fossils from two different ornithomimosaur specimens. And that helped them determine a range of size for the entire species and when they lived. What they learned is that both large and small ornithomimosaurs co-existed during that time period.

“We previously knew there were large and small ornithomimosaurs at various points in time, but we did not know what was going on at this particular period of time in the Cretaceous in North America, and this helps to fill that gap,” Cullen said. “Our finding helps fill in a previously missing piece of the puzzle of the evolutionary and biogeographic history of ornithomimosaurs.”