Mental Floss

Dinosaurs Arrived in the Northern Hemisphere Earlier Than We Thought, Fossil Suggests

A small dinosaur has made a big change in the field of paleontology.

ByCaLea Johnson|
Gabriel Ugueto‘s illustration of Ahvaytum bahndooiveche.
Gabriel Ugueto‘s illustration of Ahvaytum bahndooiveche. | Gabriel Ugueto

Paleontologists were generally on the same page about how dinosaurs spread throughout Pangea. Evidence showed that dinosaurs originated in the southern part (Gondwana) of the supercontinent and headed to the northern half (Laurasia) over millions of years, before the infamous asteroid wiped them out. Now, as Gizmodo reports, a chicken-sized fossil is throwing a wrench into the narrative. 

A new study published in the Zoological Journal of the Linnean Society suggests that dinosaurs roamed Laurasia earlier than scientists thought. A team of American researchers uncovered a new species, Ahvaytum bahndooiveche—likely a smaller, atypical relative of sauropods (usually known for their large size, long necks and tails, four legs, and herbivorous diet)—in Wyoming, which was close to the equator when it was part of Laurasia. The full-grown dinosaur was just 12 inches tall and about 3 feet long. 

Although scientists don’t have a complete specimen, they have been analyzing the Ahvaytum bahndooiveche fossils and surrounding rock sediment since 2013 using radioisotopic dating (a method that determines age by measuring radioactive decay). They estimate the fossil to be over 230 million years old, which makes it the earliest Laurasian dinosaur ever discovered. It’s about the same age as the oldest fossils found in what was once Gondwana.

“We have, with these fossils, the oldest equatorial dinosaur in the world—it’s also North America’s oldest dinosaur,” Dave Lovelace, a research scientist at the University of Wisconsin Geology Museum and first author of the study, said in a statement. The surprising discovery means dinosaurs likely traveled to Laurasia from Gondwana much earlier than previously thought.

Gizmodo reports that Ahvaytum bahndooiveche was found on the ancestral territory of the Eastern Shoshone. Tribal elders and middle school students suggested the scientific name of the fossil's species, which translates to “long ago dinosaur” in the Eastern Shoshone language. 

Read More About Dinosaurs:

Home/DINOSAURS