Scientists have successfully reconstructed the prehistoric air that dinosaurs once breathed by analyzing fossilized teeth, offering an unprecedented look into Earth’s ancient climate.
The groundbreaking study used geochemical markers preserved in tooth enamel to estimate atmospheric carbon dioxide levels during the Mesozoic Era, bringing researchers a step closer to understanding how the environment evolved over millions of years.
By studying oxygen isotopes trapped in the dental enamel of dinosaurs, researchers were able to infer the composition of the atmosphere that existed during the Jurassic and Cretaceous periods.
This method has enabled scientists to piece together how the prehistoric air was recreated from biological evidence that has survived for over 150 million years.
Isotope clues hidden in dinosaur tooth enamel
The study, led by geochemist Dingsu Feng of the Georg August University of Göttingen in Germany, focused on a rare oxygen isotope known as oxygen-17. This isotope, less abundant in atmospheric carbon dioxide due to natural processes, leaves a unique signature in the bodies of air-breathing animals.
When organisms inhale CO2, part of this chemical fingerprint becomes incorporated into their body water and eventually into the hard tissue of teeth during the biomineralization process.
Paleontologist and geochemist Thomas Tütken of Johannes Gutenberg University in Mainz, Germany, explained that this preserved signal in tooth enamel allows researchers to trace changes in atmospheric CO2.
Oxygen isotopes in dinosaur teeth were used to infer CO2 concentrations in the atmosphere during the Mesozoic Era. Given primary productivity levels similar to today, late Jurassic CO2 levels were four times higher than pre-industrial levels. In PNAS: https://t.co/wP1qyiuUm8 pic.twitter.com/FbZFprUN18
— PNASNews (@PNASNews) August 8, 2025
He emphasized that even after millions of years, these isotopic imprints remain intact and provide valuable insight into both ancient air composition and photosynthetic activity on a global scale.
Modern teeth confirm method, fossils reveal history
Initially, Feng’s team confirmed the accuracy of the method by analyzing modern animal teeth, which reflected current CO2 levels.
They then applied the same technique to fossilized enamel from dinosaur specimens housed in museum collections across Europe. These samples, originally collected for dietary studies, revealed striking data about ancient atmospheric conditions.
Their findings suggest that CO2 levels during the late Jurassic period reached around 1,200 parts per million, while in the late Cretaceous, levels dropped to roughly 750 parts per million.
In contrast, today’s atmosphere holds about 430 parts per million and continues to rise. The team believes intense volcanic activity during the Mesozoic era likely contributed to these elevated CO2 concentrations.
Volcanic spikes detected in T. rex and Sauropod teeth
Two teeth in particular, one from a Tyrannosaurus rex and another from a sauropod species called Kaatedocus, showed especially high oxygen isotope anomalies.
Tütken noted these spikes may indicate short-term surges in atmospheric CO2, possibly linked to massive volcanic eruptions such as those triggered by flood basalt events. These variations, he added, show that CO2 levels may have fluctuated by as much as 160 percent over short geological intervals.
With their technique validated, the team now plans to analyze fossil teeth from the Permian-Triassic extinction event, also known as the Great Dying.
Occurring 252 million years ago, this event wiped out the majority of life on Earth and has been tied to long-lasting volcanic activity that drastically altered the planet’s climate.
By reconstructing the CO2 profile from that period, researchers hope to better understand how extreme atmospheric changes affected life. The study, published in the Proceedings of the National Academy of Sciences, marks a major step forward in using ancient biological material to explore Earth’s climatic past.
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