Madison Reporter

Dinosaurs may have roamed the northern hemisphere millions of years earlier than previously thought, according to new research from the University of Wisconsin–Madison. A newly described dinosaur species, Ahvaytum bahndooiveche, discovered in Wyoming by paleontologists at UW–Madison, challenges the prevailing belief that dinosaurs first emerged in Gondwana before spreading to Laurasia.

The fossil remains were found in 2013 in what is now Wyoming but was once near the equator on Laurasia. These fossils are estimated to be around 230 million years old, making Ahvaytum bahndooiveche the oldest known dinosaur from Laurasia and comparable in age to those from Gondwana.

"We have, with these fossils, the oldest equatorial dinosaur in the world — it’s also North America’s oldest dinosaur," says Dave Lovelace, a research scientist at the University of Wisconsin Geology Museum who co-led the study with graduate student Aaron Kufner.

Lovelace and his team worked for years to analyze and establish these fossils as a new species. While they did not find a complete specimen, enough parts were discovered to identify Ahvaytum bahndooiveche as likely an early sauropod relative. Sauropods included large herbivorous dinosaurs like titanosaurs; however, Ahvaytum bahndooiveche was much smaller.

"It was basically the size of a chicken but with a really long tail," Lovelace explains. The researchers suggest this dinosaur lived during or soon after significant climatic changes during the Carnian pluvial episode which transformed deserts into more habitable environments for early dinosaurs.

High-precision radioisotopic dating revealed that this species existed about 230 million years ago. Additionally, tracks found in older rocks indicate that similar creatures were present even earlier.

The naming process for Ahvaytum bahndooiveche involved collaboration with Eastern Shoshone tribal elders and middle school students since its discovery site is on their ancestral lands. Amanda LeClair-Diaz highlights this collaboration: "The continuous relationship developed between Dr. Lovelace, his team, our school district, and our community is one of the most important outcomes."

This partnership aimed to incorporate Indigenous knowledge into scientific practices while ensuring mutual benefits from research efforts. LeClair-Diaz notes that such work "breaks this cycle and creates an opportunity for reciprocity."