230 Million-Year-Old Fossil From Wyoming Challenges Dinosaur Origin Theories

Although paleontologists have debated the origin and spread of dinosaurs for decades, the widely accepted theory was that they appeared in the southern part of the Pangea continent 200 million years ago and spread north a few million years later. A new study dramatically changes the conversation.

University of Wisconsin-Madison (UW-Madison) paleontologists have announced the discovery of a new dinosaur that challenges conventional theories about the origin and spread of dinosaurs. The location and age of the newly-described fossils suggest that dinosaurs roamed northern Pangea millions of years earlier than previously thought. The results were detailed on January 8 Study Published in Zoological Journal of the Linnean Society.

Dave Lovelace of the University of Wisconsin Geology Museum, who co-led the study, said in a UW-Madison statement. “We now have this piece of evidence that shows dinosaurs were in the Northern Hemisphere much earlier than we thought.”

Paleontologists uncovered the theory-defying fossil in 2013 in present-day Wyoming. Due to Earth’s shifting tectonic plates, this region was located near the equator 200 million years ago, Laurasia, the northern half of Pangaea (the southern half was called Gondwana. ) As the remains fragmented, paleontologists were able to attribute the fossils to a new dinosaur species they named. Abhaytum BahnduycheWhich was probably an early one sauropod relative AhvaitumHowever, the iconic long-necked herbivores looked very different.

“It was basically the size of a chicken but had a really long tail,” Lovelace said. “We think of dinosaurs as these giant behemoths, but they didn’t start out that way.” The adult specimen was only one foot long (30.5 cm) and about three feet tall (91.4 cm).

Perhaps most surprisingly, however, is the fossil’s age. Lovelace and his colleagues used radioisotopic dating (a method of determining the age of materials by measuring radioactive decay) to determine where they found the rock layers. Ahvaitum The fossils—and thus roughly the remains themselves—are about 230 million years old. This makes Ahvaitum According to the study, it is the oldest known Laurasian dinosaur and is equivalent in age to the oldest Gondwanan dinosaur. Dinosaurs first appeared during the Triassic period, about 230 million years ago. This era, which lasted from about 252 to 201 million years ago, saw the rise of the earliest dinos before they became dominant in the Jurassic period.

“We have these fossils, the oldest equatorial dinosaur in the world — it’s also the oldest dinosaur in North America,” Lovelace added. The fact that the oldest Laurasian dinosaur is as old as the oldest known Gondwanan dinosaur challenges the theory that dinosaurs originated in the south of the ancient continent and spread north millions of years later.

The discovery site is within the ancestral lands of the Eastern Shoshone tribe. As a result, the researchers partnered with tribal members throughout their work and included Eastern Shoshone elders and middle school students in choosing new dinosaur names. Ahvaitum made friends Roughly translates to “long ago dinosaur” in the Eastern Shoshone language.

The region also received additional exploration. The team detected an early dinosaur-like footprint in the old rock layers, meaning dinosaurs or dinosaur-related creatures were already calling Laurasia home. Ahvaitum. Paleontologists also uncovered a fossil Newly described amphibianswhich was named in the Eastern Shoshone language.

The chicken-sized discovery challenges long-held theories about how dinosaurs spread across Pangea Ahvaitum It finally paints a clearer picture of the animals that lived—and where—on Earth millions of years ago.