A recently unearthed dinosaur fossil in Wyoming has fundamentally altered scientists’ understanding of when dinosaurs first appeared in North America, Science Blog reports.
The discovery, dating back millions of years earlier than previously thought, challenges long-held theories about how these ancient reptiles spread across the globe.
The newly identified species, Ahvaytum bahndooiveche, is the oldest known dinosaur from North America and the oldest equatorial dinosaur ever discovered worldwide.
“This is a groundbreaking find,” said Dave Lovelace, a research scientist at the University of Wisconsin Geology Museum, who co-led the study published in the Zoological Journal of the Linnean Society.
The chicken-sized dinosaur, which lived approximately 230 million years ago, inhabited what is now Wyoming. At the time, this region was located near the equator on the ancient supercontinent of Laurasia.
“It was basically the size of a chicken but with a really long tail,” Lovelace explained. “We think of dinosaurs as these giant behemoths, but they didn’t start out that way.”
Measuring just over one foot tall and three feet long, the creature underscores the modest beginnings of a lineage that would later dominate the planet.
The discovery suggests dinosaurs appeared in the northern hemisphere much earlier than previously believed.
“We’re filling in some of the story,” Lovelace said. “This evidence shows that dinosaurs were here in North America earlier than anyone thought.”
The timing of this species’ existence coincides with a significant climate shift known as the Carnian pluvial episode (234–232 million years ago). During this period, extreme desert environments transformed into habitable areas, potentially facilitating the spread of dinosaurs across new regions.
Ahvaytum bahndooiveche’s discovery also represents a milestone in scientific collaboration. For the first time, a dinosaur species has been named in the Eastern Shoshone language, honoring the Indigenous peoples whose ancestral lands yielded the fossils.
Amanda LeClair-Diaz, a co-author of the study and member of the Eastern Shoshone and Northern Arapaho Tribes, emphasized the importance of the collaborative approach.
“Typically, research in Indigenous communities has been one-sided, benefiting researchers while excluding the community,” LeClair-Diaz said. “This work breaks that cycle, creating reciprocity in the research process.”
The name Ahvaytum bahndooiveche, meaning “long ago dinosaur” in Shoshone, symbolizes this partnership and sets a new precedent for inclusivity in paleontological research.
