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Scientists have discovered that the increase in oxygen levels is related to the rise of dinosaurs in North America about 215 million years ago.
A new technique for measuring oxygen levels in ancient rocks shows that oxygen levels in North American rocks have jumped by nearly a third in just a few million years. , paving the way for an expansion of dinosaurs in the tropics of North America and elsewhere. This is presented at a conference at the Goldschmidt Geochemistry Conference in Barcelona.
US-based scientists have developed a new technique to release small amounts of gas trapped in ancient carbonate minerals. The gases are then fed directly into a mass spectrometer, which measures their composition.
Professor Morgan Schaller (Rensselaer Polytechnic Institute, New York), Principal Investigator, said, "We tested rocks from the Colorado Plateau and Newark Basin that formed simultaneously about 1000 km from one of the On the supercontinent of Pangea. Our results show that over a period of about 3 million years – which is very fast geologically – oxygen levels in the atmosphere have gone from 15% to 19%. % about. For comparison, today's atmosphere contains 21% oxygen. We really do not know what might have caused this increase, but we also see a drop in CO2 levels at that time. "
"We expect this change in oxygen concentration to have been a global shift and, in fact, we have found the change in samples 1000 km apart. What is remarkable is that at the peak of oxygen, we see the first dinosaurs appear in the North American tropics, the Chindesaurus. The Sauropods followed soon after. Once again, we can not yet say whether it was a global development, and the dinosaurs will not rise to ecological dominance in the tropics before the end of the final Triassic. What we can say is that it shows that the evolution of the environment 215 million years ago was conducive to their evolutionary diversification, but it is obvious that oxygen levels may have not the only factor to consider. "
Chindesaurus was a standing carnivorous dinosaur (about 2 m long and nearly 1 m tall). Very common in North America, with its origins in the tropics of North America, it was a late Triassic dinosaur characteristic of the American Southwest. It was originally discovered in the Petrified Forest National Park. The Sauropods, which appeared shortly after Chindesaurus, were the largest animals on the planet.
Mike Benton, a professor at Bristol University, said, "The first dinosaurs were quite small, but a high oxygen content in the atmosphere was often associated with a trend towards greater size. This new result is interesting because the timing of the rise in oxygen and the appearance of the dinosaurs is good, although the dinosaurs became abundant in South America a little earlier, about 232 million years ago. Professor Benton did not participate in this work; it's an independent comment.
By the time the gases were trapped, the Colorado Plateau and Newark Basin were part of the giant supercontinent, Pangea. Both were located near the equator. Rocks containing oxygen and carbon dioxide have been dated by measuring the radioactive decay of uranium found in the samples.
GOLDSCHMIDT CONFERENCE
Header Image Credit: Jeff Martz
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