230-million-year-old fossil from Wyoming challenges theories of the origin of dinosaurs

Although paleontologists have debated the origins and spread of dinosaurs for decades, the widely accepted theory was that they emerged in the southern part of the ancient continent of Pangea more than 200 million years ago, and spread only towards the north millions of 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 the conventional theory of the origin and spread of dinosaurs. The location and age of the fossils just described suggest that dinosaurs roamed the northern regions of Pangea millions of years earlier than previously thought. The results were detailed in a January 8 to study published in the Zoological Journal of the Linnean Society.

“We’re kind of filling in part of this story, and we’re showing that the ideas that we’ve had for so long — ideas that were supported by the fragmented evidence that we had — were not right,” Dave. Lovelace of the University of Wisconsin Museum of Geology, who co-led the study, said in a UW-Madison. declaration. “We now have this evidence that shows that dinosaurs were here in the northern hemisphere much earlier than we thought.”

Paleontologists discovered theory-challenging fossils in what is now Wyoming in 2013. Due to Earth’s shifting tectonic plates, this region was located near the equator more than 200 million years ago in Laurasia, the northern half of Pangea (the southern half was called Gondwana). ). While the remains were fragmented, paleontologists were able to attribute the fossils to a new species of dinosaur that they named. Ahvaytum bahndooivechethat was probably a start sauropod relative Ahvaytumhowever, it looked very different from the iconic long-necked herbivores.

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

Perhaps the most shocking, however, is the age of the fossil. Lovelace and his colleagues used radioisotope dating (a method of determining the age of materials through radioactive decay) to determine that the rock layers where they found the Ahvaytum the fossils – and thus roughly the remains themselves – were about 230 million years old. This does Ahvaytum the oldest known Laurasian dinosaur, and roughly equivalent in age to the earliest known Gondwana dinosaurs, according to the study. 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 first dinosaurs, before they became dominant in the Jurassic period.

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

The site of the discovery is on the ancestral lands of the Eastern Shoshone Tribe. As a result, the researchers partnered with tribe members throughout their work, and included Eastern Shoshone elders and middle school students in choosing the new dinosaur’s name. Ahvaytum bahndooiveche roughly translated as “dinosaur long ago” in the Eastern Shoshone language.

The region also yielded additional discoveries. The team identified an early dinosaur footprint in the oldest rock layers, meaning that dinosaurs or dinosaur-related creatures called Laurasia home even before that. Ahvaytum. Paleontologists have also discovered the fossil of a amphibians just describedwhich was also called in the Eastern Shoshone language.

In a challenge to long-held theories about how dinosaurs spread across Pangea, the discovery of the size of chicken. Ahvaytum ultimately paints a clearer picture of the creatures that walked the Earth – and where – millions of years before us.