MADRID 5 (EUROPE PRESS)
A geological study of the rock formation that enclosed a fossilized example of the world’s largest “raptor” shows that it is 10 million years older than previously believed. The report, co-authored by a researcher at the University of Kansas (KU, appeared in the journal Geosciences.
“We determined the age of the Utahraptor dinosaur and found that it was much older than previously assumed,” he said. it’s a statement Gregory Ludvigson, a senior scientist emeritus with the Kansas Geological Survey at KU, who collaborated on the research. “That finding has important implications for the evolutionary history of dinosaurs.”
Fieldwork was carried out in Utah at the well-known Utahraptor Ridge site, named for the larger cousins of the ferocious velociraptor dinosaur, one of the protagonists of the Jurassic Park saga.
The ridge is home to Stikes Quarry, a quicksand deposit filled with dinosaur fossils that are largely intact and preserved, in the same positions as when they died. Stikes Quarry is part of the Cedar Mountain Formation, a unit of rock that contains fossils of more types of dinosaurs than any other formation in the world.
“We also learned to our complete surprise that the rock strata at the Stikes Dinosaur Quarry were deposited during an episode of global change known as the Weissert Event,” Ludvigson said.. “This is an agenda-setting discovery that will reverberate for decades.”
More than a decade ago, Ludvigson, along with Jim Kirkland, state paleontologist with the Utah Geological Survey, and Matt Joeckel, state geologist and director of the Division of Studies and Conservation at the University of Nebraska-Lincoln, teamed up to address that question. .
The scientists and colleagues who recruited They adopted two research approaches: One path, uranium/lead dating of zircon crystals, involved analyzing samples of these minerals collected at different depths in rock layers. The second looked at changes in the relative abundance of two types of stable carbon isotopes found in buried organic matter.
By comparing the results to periods in Earth’s history when global changes in the carbon cycle were known to occur, the team showed that rocks in the Gato Amarillo Member of the Cedar Mountain Formation, and Utahraptor fossils that found within, are 10 million years older than established. Previous estimates put the age of the rocks and fossils at 125 million years.
“That’s a long evolutionary time”Ludwigson said. “It’s kind of a vindication of something that Jim has discussed for some time, but arguing doesn’t put an absolute age on it, and that’s important to him.”
The revised age indicates that the rocks in Stikes Quarry are at least 135 million years old. The lower part of the Yellow Cat Member encompasses even older strata. The findings bridge the gap in the rock record at the boundary between the Jurassic and Cretaceous periods in Utah.
“Before, we had a gap of 25 million years between them,” said Kirkland, who first named and described the dinosaur Utahraptor ostrommaysi in 1993. “That’s a third of the age of mammals, more than twice as long as hominins.” evolution. It’s a lot of time. Anything can happen for 25 million years if you don’t have a record of what’s happening. We’ve plugged that record in, for the most part.”
