Trapped in the enamel of fossilized dinosaur teeth is a fascinating glimpse into the Earth’s atmospheric past stretching back 150 million years. A recent study shows that carbon dioxide levels back then were far higher than today, thanks to the air dinosaurs breathed in while they lived.
The research team — from the universities of Göttingen, Mainz, and Bochum — analyzed the enamel of dinosaur teeth found in North America, Africa, and Europe. Their study shows that around 150 million years ago, during the late Jurassic period, carbon dioxide levels were around four times higher than before the industrial period. Around 73 to 66 million years ago, in the late Cretaceous period, the level was three times as high as today.
Analyzing Dinosaur Teeth
Those findings are made possible as every time a dinosaur inhaled, enamel would store oxygen isotopes, explains Dingsu Feng, with the University of Göttingen’s Department of Geochemistry and lead author of the study. This enabled scientists to use these fossils as an environmental time capsule. Based on the oxygen anomaly in the isotopes, the scientists could work out how much CO2 was in the atmosphere.
“The most important finding is that we know that the CO2 levels and the biomass production from all the plants at that time was very different reconstructed from the dinosaur teeth,” Feng says. “The exciting thing is that all those anomalies in the air and isotope information are well preserved in the teeth.”
Previously, researchers relied on carbonates in soil or marine proxies to understand the atmosphere and environment during the time of the dinosaurs. But as Feng says, these can offer uncertain results. This new method of analyzing fossilized dinosaur teeth can now offer a more precise picture of the atmospheric conditions on land, she says.
“The other proxies also cannot reconstruct biomass production from the plants; they can only reconstruct the CO2 levels,” she says.
That part of their study found that photosynthesis from plants was likely twice as high as it is today. This heightened biomass productivity is due to the high CO2 concentrations and higher resultant global temperatures, helping to explain the rich biodiversity and vegetation that flourished during the time of the dinosaurs.
Read More: This Bizarre, Long-Necked Dinosaur Had 500 Replaceable Teeth
Higher CO2 Levels and More Volcanic Activity
The team also discovered unusual isotope levels in individual tooth samples from Tyrannosaurus rex and Kaatedocus siberi, a dinosaur related to Diplodocus.
“From Kaatedocus siberi, we saw a very negative oxygen level preserved in the teeth,” Feng says.
That indicated high CO2 levels. Upon reconstructing the atmospheric conditions, they found CO2 levels were six times higher than today and far higher than those from other dinosaur teeth at around the same time from different locations, Feng says.
“Our hypothesis is that this is explained by the extreme volcanic activity at that time,” she adds, suggesting that particular dinosaur must have lived in an area with high activity.
“Because [volcanic] activities cause a short-term spike in CO2 levels, this has been recorded in the dinosaur teeth.”
A Dental Time Capsule
Fossilized dinosaur teeth’s new role as a climate time capsule is just one exciting prospect opened up by this study, says Fend. The method they have developed also opens the door to further research that could shed light on elements of dinosaur physiology.
Feng says her team is now investigating the dinosaur physiology information by analyzing teeth from the same periods of time and sites.
“This information for dinosaurs is still lacking,” she says. “We could possibly work out how much oxygen the dinosaurs breathed in or got from water, from food, and so on. This area of research is still new.”
Read More: Tyrannosaur Teeth Fuel Rare Fossil Find in England
Article Sources
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- University of Bochum. Dinosaur Teeth Give Glimpse of Early Earth’s Climate
