On Utahraptor's upcoming birthday cake, 10 million extra candles will be required.
Greg Ludvigson on outcrop of colorful buried soils of the Yellow Cat Member in May 2009. Credit: Matt Joeckel
Geological analysis of the rock formation that included a fossilized specimen of the largest "raptor" in the world reveals that it is 10 million years older than previously thought. The report, which was co-written by a scientist from the University of Kansas, was just published in the Geosciences magazine.
Gregory Ludvigson, an emeritus senior scientist with the Kansas Geological Survey at KU, who worked on the inquiry, said, "We determined the age of the dinosaur Utahraptor and found that it was much older than previously supposed." "That discovery has significant ramifications for the evolution of dinosaurs."
The well-known Utahraptor Ridge site, named for the bigger relatives of the vicious velociraptor dinosaur (familiar to "Jurassic Park" fans), hosted the research.
Stikes Quarry, a quicksand deposit full of dinosaur fossils that are mostly intact and preserved—in essentially the same positions as when they died—is located on the ridge. The Cedar Mountain Formation, a geological unit that has more dinosaur fossils than any other formation in the world, includes Stikes Quarry.
To our total amazement, we also discovered that the rock strata from the Stikes Dinosaur Quarry were deposited during the Weissert Event, Ludvigson added. "This is a discovery that will set the agenda for decades."
In order to answer that question, Ludvigson teamed up with Matt Joeckel, a state geologist and the director of the Conservation and Survey Division at the University of Nebraska-Lincoln, as well as Jim Kirkland, a state paleontologist with the Utah Geological Survey.
Two research strategies were used by the scientists and colleagues they attracted: Zircon crystals could be dated using uranium/lead by examining samples of these minerals that were taken from various depths in the rock strata. In the second, two kinds of stable carbon isotopes that are found in buried organic debris were examined for changes in relative abundance.
The scientists demonstrated that rocks in the Yellow Cat Member of the Cedar Mountain Formation—and the Utahraptor fossils found there—are 10 million years older than previously thought by comparing findings to eras in Earth's history during which it is known that the carbon cycle underwent worldwide alterations.
The rocks and fossils are thought to be 125 million years old, according to earlier calculations.
That much time has passed throughout evolution, remarked Ludvigson. It's sort of a confirmation of something Jim has been debating for a while, but debating doesn't give it a precise age, and that's essential to him.
According to the updated age, the Stikes Quarry rocks are at least 135 million years old. Even earlier strata are included in the Yellow Cat Member's lower portion. The discoveries fill in the gap in Utah's rock record at the juncture of the Jurassic and Cretaceous Periods.
The dinosaur Utahraptor ostrommaysi's original name and description were given by Kirkland in 1993. "Before, we had a 25-million-year gap between them," he stated. "That's more than twice as long as the evolution of hominids and a third of the age of mammals. It's a large period of time. If there are no records of what is happening, anything could happen over a period of 25 million years. Most of that record has been promoted by us.
