230-million-year-old fossil from Wyoming challenges dinosaur origin theories

Although paleontologists have debated the origin and distribution of dinosaurs for decades, the widely accepted theory is that they emerged over 200 million years ago in the southern part of the ancient continent of Pangea and only spread northward millions of years later. A new study dramatically changes the discussion.

Paleontologists at the University of Wisconsin–Madison (UW–Madison) announced the discovery of a new dinosaur that challenges conventional theories about the origin and distribution of dinosaurs. The location and age of the newly described fossils suggest that dinosaurs roamed the northern regions of Pangea millions of years earlier than previously thought. The findings were detailed in a Jan. 8 report study published in the Zoological Journal of the Linnean Society.

“We’re sort of adding to a part of that story and showing that the ideas we held for so long – ideas that were supported by the fragmented evidence we had – weren’t entirely right,” Dave Lovelace of the University of Wisconsin Geology Museum, who co-led the study, said in a UW-Madison statement opinion. “We now have this evidence that shows dinosaurs were in the Northern Hemisphere much earlier than we thought.”

The paleontologists discovered the theory-defying fossils in what is now Wyoming in 2013. Due to shifting Earth’s tectonic plates, this region was near the equator over 200 million years ago on Laurasia, the northern half of Pangea (the southern half was called Gondwana). . ). While the remains were fragmented, paleontologists were able to assign the fossils to what they named a new species of dinosaur Ahvaytum bahndooivechewhich was probably early Sauropods relative. AhvaytumHowever, they looked very different from the iconic long-necked herbivores.

“It was basically the size of a chicken but had a really long tail,” Lovelace said. “We think of dinosaurs as huge behemoths, but they didn’t start out that way.” The adult specimen was just over 12 inches tall and about 36 inches long.

Perhaps most shocking, however, is the age of the fossil. Lovelace and his colleagues used radioisotope dating (a method of determining the age of materials by measuring radioactive decay) to determine the rock layers in which they found it Ahvaytum Fossils – and therefore roughly the remains themselves – were around 230 million years old. That makes Ahvaytum According to the study, it is the oldest known Lauras dinosaur and is about the same age as the earliest known Gondwan dinosaurs. Dinosaurs first appeared in the Triassic period, about 230 million years ago. It was during this era, which lasted about 252 to 201 million years ago, that the first dinosaurs emerged before becoming dominant in the Jurassic period.

“With these fossils, we have the oldest equatorial dinosaur in the world – it is also North America’s oldest dinosaur,” Lovelace added. The fact that the oldest known Lauras dinosaur is about the same age as the earliest known Gondwan dinosaurs consequently calls into question the theory that dinosaurs originated in the south of the ancient continent and only spread northward millions of years later.

The site is on the ancestral lands of the Eastern Shoshone Tribe. As a result, the researchers collaborated with tribal members throughout their work and involved Eastern Shoshone elders and middle school students in choosing the new dinosaur’s name. Ahvaytum bahndooiveche In the Eastern Shoshone language, this roughly translates to “dinosaurs long ago.”

The region also produced other finds. The team identified an early dinosaur-like footprint in older rock layers, meaning dinosaurs or dinosaur-related creatures called Laurasia home before Ahvaytum. The paleontologists also discovered the fossil of one newly described amphibianwhich was also named in the Eastern Shoshone language.

The discovery of the chicken-sized dinosaur challenges long-standing theories about the distribution of dinosaurs in Pangea Ahvaytum ultimately paints a clearer picture of the creatures that lived on Earth millions of years before us – and where.