14 DAY TRIAL // A new study recently published by researchers at the University of Innsbruck suggests that some very popular theories about the origins and evolution of life and Earth's climate may require some revising. The investigation measured atmospheric oxygen levels over the past 220 million years.
The research suggests that even the fact that dinosaurs reached such impressive sizes may have not been caused by the factors scientists believed. Previously, it was thought that higher concentrations of oxygen in the air were responsible for this gigantism, but this appears not to have been the case.
UI investigator Ralf Tappert, who was the leader of the research group, says that the concentration of atmospheric oxygen over the past 220 million years was significantly lower than first calculated. This conclusion is based on a study of fossil resins, such as amber.
These resins are some of the few organic materials that can be used to track back Earth's chemical evolution over such long timeframes, says Tappert. His team also included colleagues from the University of Alberta, in Canada, and universities in Spain and the United Kingdom.
“Compared to other organic matter, amber has the advantage that it remains chemically and isotopically almost unchanged over long periods of geological time,” the team leader explains. Tappert holds an appointment with the UI Institute of Mineralogy and Petrography.
His group, whose work was published in a recent issue of the scientific journal Geochimica et Cosmochimica Acta, included paleontologists, geochemists, and mineralogists. This meant that the group could analyze the fossil resins from a number of perspectives, ensuring top-notch results.
“During photosynthesis plants bind atmospheric carbon, whose isotopic composition is preserved in resins over millions of years, and from this, we can infer atmospheric oxygen concentrations,” Tappert explains. For this study, the team compared ratios of the stable carbon isotopes 12C and 13C, Astrobiology Magazine reports.
One of the most interesting implications for this study is that the large sizes of dinosaurs may have not been caused by larger amounts of oxygen in Earth's atmosphere. “We do not want to negate the influence of oxygen for the evolution of life in general with our study, but the gigantism of dinosaurs cannot be explained by those theories,” the UI investigator adds.
Today, Earth's atmosphere is made up of 21 percent oxygen, but concentrations may have been much small in the past. The new study, which was conducted on 538 amber samples, suggests an atmospheric oxygen concentration of 10 and 15 percent some 220 million years ago.