According to a study presented at the Goldschmidt conference in Barcelona, the increase in oxygen levels that occurred 215 million years ago would be linked to the rise of dinosaurs in the area of present-day North America.
Researchers measured oxygen levels in some ancient rocks in North America and saw a peak in oxygen levels with the latter increasing by almost a third in just three million years. This increased availability of oxygen, according to the researchers, would be linked to an expansion of dinosaurs, and not only in North America.
The researchers used a new technique to measure the gases trapped inside the rocks. The method involves the use of a mass spectrometer that measures the composition of the gases. The researchers analyzed the rocks of the Colorado plateau and the Newark basin, two conglomerates that formed more or less at the same time and were separated by about 600 miles away in the supercontinent of Pangea.
Analysis has shown that in about 3 million years, just over the blink of an eye in geological terms, oxygen levels have increased from about 15% to about 19% (today we are at 21%). Schaller still does not know what may have caused this “sudden” increase, probably there is a global climate change that has also seen a drop in carbon dioxide levels.
However, he has discovered that it was dinosaurs in particular that took advantage of it: during the oxygen peak, the first dinosaurs appeared in the North American tropics, areas that at the time of the supercontinent Pangaea were located near the equator, particularly those of the genus Chindesaurus.
These last ones were then followed by the sauropods and by a wide evolutionary diversification. Oxygen levels may not have been the only determining factor, according to Schaller himself.