New Evidence Suggests Dinosaurs Stomped Through the Northern Hemisphere Millions of Years Sooner!

When and how did dinosaurs initially arise and proliferate across the globe more than 200 million years prior? This query has been a matter of contention among paleontologists grappling with incomplete fossil records.

The predominant theory suggests that the reptiles originated in the southern section of the ancient supercontinent Pangea, known as Gondwana, ages before migrating to the northern region referred to as Laurasia.

However, a newly identified dinosaur, whose fossils were uncovered by paleontologists at the University of Wisconsin–Madison, is disputing this narrative, presenting evidence that these reptiles existed in the northern hemisphere millions of years earlier than previously recognized.

The UW–Madison researchers have been scrutinizing the fossil remains since their initial discovery in 2013 in what is now Wyoming, an area once near the equator on Laurasia. The organism, designated Ahvaytum bahndooiveche, is recognized as the oldest known Laurasian dinosaur, with fossils dated to approximately 230 million years old, making it comparable in age to the earliest known Gowanian dinosaurs.

Scientists from UW–Madison and their research collaborators detail their finding in the Zoological Journal of the Linnean Society on January 8, 2025.

“With these fossils, we possess the oldest equatorial dinosaur on the planet—it is also North America’s oldest dinosaur,” remarks Dave Lovelace, a research scientist at the University of Wisconsin Geology Museum who co-guided the research along with graduate student Aaron Kufner.

Unearthed from a rock layer known as the Popo Agie Formation, it required years of thorough examination by Lovelace and his associates to classify the fossils as a new dinosaur species and ascertain their estimated age.

Although the team does not possess a complete specimen—something exceedingly rare for early dinosaurs—they successfully uncovered sufficient fossils, primarily fragments of the species’ legs, to definitively recognize Ahvaytum bahndooiveche as a dinosaur, most likely as a very early sauropod relative.

Sauropods constituted a category of herbivorous dinosaurs that featured some notably enormous species like those within the aptly-titled group of titanosaurs. The remotely related Ahvaytum bahndooiveche existed millions of years earlier and was significantly smaller—much smaller.

“It was roughly the size of a chicken but had a notably lengthy tail,” Lovelace explains. “We envision dinosaurs as these massive creatures, yet they didn’t begin that way.”

Indeed, the type specimen of Ahvaytum bahndooiveche, which was mature yet could have been marginally larger at its peak age, reached slightly over one foot in height and was approximately three feet in length from head to tail. While scientists have yet to locate its skull material, which could elucidate its diet, other closely related early sauropod-line dinosaurs were carnivorous and would likely have been omnivorous.

The researchers identified the scant known bones of Ahvaytum within a rock layer just a little above that of a recently identified amphibian that they also unearthed.

The indications imply that Ahvaytum bahndooiveche thrived in Laurasia during or shortly after a significant climatic shift recognized as the Carnian pluvial episode, which has previously been linked to an initial wave of diversification among dinosaur species.

The environment during that era, spanning roughly from 234 to 232 million years ago, was considerably wetter than it had been before, converting vast, scorching expanses of desert into more suitable habitats for early dinosaurs.

Lovelace and his team conducted high-precision radioisotopic dating of the rocks containing Ahvaytum’s fossil remains, revealing their age.

fossils, which indicated that the dinosaur existed in the northern hemisphere approximately 230 million years ago. The scientists also uncovered an early dinosaur-like footprint in somewhat older sediments, showing that dinosaurs or their relatives were already inhabiting the area a few million years before Ahvaytum.

“We are essentially piecing together part of this narrative, revealing that the concepts we have maintained for such an extended period—concepts based on the limited evidence we previously possessed—were not entirely accurate,” states Lovelace. “We now possess this evidence indicating that dinosaurs were present in the northern hemisphere significantly earlier than we had anticipated.”

Although the scientific group is assured they have identified North America’s oldest dinosaur, it also marks the first dinosaur species to be designated in the tongue of the Eastern Shoshone Tribe, whose ancestral territory encompasses the location of the fossil discoveries. Elders from the Eastern Shoshone tribe and middle school pupils were crucial to the naming process. Ahvaytum bahndooiveche roughly translates to “ancient dinosaur” in the Shoshone language.

Numerous tribal members also collaborated with Lovelace and his UW–Madison associates as the researchers aimed to enhance their field methodologies and show greater respect for the land by weaving the insights and viewpoints of the Indigenous peoples into their efforts.

“The ongoing relationship cultivated between Dr. Lovelace, his team, our educational district, and our community stands out as one of the most significant results of the uncovering and christening of Ahvaytum bahndooiveche,” remarks Amanda LeClair-Diaz, a co-author of the study and a member of the Eastern Shoshone and Northern Arapaho Tribes.

LeClair-Diaz serves as the Indian education coordinator at Fort Washakie school and oversaw the naming process with students and tribal elders—a procedure that commenced under her predecessor, Lynette St. Clair.

“Generally, the research approach in communities, particularly Indigenous communities, has tended to be unilateral, with researchers solely profiting from the studies,” LeClair-Diaz explains. “The collaboration we have established with Dr. Lovelace disrupts this cycle and fosters a chance for reciprocity within the research framework.”