In a groundbreaking study that promises to reshape our understanding of Earth’s ancient atmosphere, an international team of researchers has pioneered a novel approach to reconstruct atmospheric carbon dioxide (CO₂) levels during the Mesozoic era by analyzing oxygen isotopes preserved in fossilized dinosaur tooth enamel. This method, developed through collaborative efforts between the Universities of Göttingen, Mainz, and Bochum, leverages the remarkable stability and isotopic signatures held within dinosaur teeth, offering an unprecedented window into the climate dynamics that prevailed between 252 and 66 million years ago.
The Mesozoic era, often romanticized as the age of dinosaurs, was a period of profound geological and climatic transformations. However, despite its significance, scientists have long grappled with limitations in precisely quantifying atmospheric CO₂ concentrations during this interval. Prior investigations primarily depended on indirect measures such as soil carbonates and marine proxies—chemical signatures and fossil evidence derived from oceanic sediments. Though invaluable, such proxies carry inherent uncertainties, especially in their ability to reflect terrestrial atmospheric conditions. The newly introduced tooth enamel isotope analysis bridges this gap by focusing exclusively on land vertebrates that directly interacted with atmospheric oxygen.
At the heart of this innovative technique lies the detailed examination of the ratio between oxygen isotopes, notably ^18O to ^16O, ingrained within the enamel of dinosaur teeth. Enamel, due to its dense and crystalline nature, resists diagenetic alteration over millions of years, effectively locking in isotopic ratios reflective of the ambient oxygen inhaled by these creatures. Because oxygen isotope ratios in the atmosphere fluctuate with variations in CO₂ levels and plant photosynthesis rates, analyzing these ratios offers a robust proxy for reconstructing ancient atmospheric conditions, surpassing limitations of previous sedimentary-based methods.
The researchers meticulously sampled dinosaur teeth excavated from diverse geographical locations across North America, Africa, and Europe. These specimens spanned pivotal sections of the Mesozoic—specifically the late Jurassic and late Cretaceous periods. By comparing isotopic compositions across this temporal and spatial range, the team uncovered compelling evidence that atmospheric CO₂ concentrations during the late Jurassic, approximately 150 million years ago, were roughly quadruple those of the pre-industrial era. Similarly, the late Cretaceous atmosphere, from about 73 to 66 million years ago, exhibited CO₂ levels threefold greater than today’s.
Intriguingly, teeth from two prominent dinosaur species—Tyrannosaurus rex and Kaatedocus siberi, a relative of Diplodocus—revealed anomalous isotopic signatures suggestive of episodic spikes in CO₂ concentrations. These fluctuations likely correlate with significant geologic events, with the Deccan Traps volcanic eruptions at the close of the Cretaceous period standing out as a plausible driver. These massive basaltic lava flows, emanating from what is modern-day India, would have released tremendous volumes of greenhouse gases, temporarily intensifying atmospheric CO₂ and precipitating shifts in global climates.
Beyond atmospheric composition, this research illuminates the biospheric response to elevated CO₂. The data indicates that photosynthetic activity—both terrestrial and aquatic—was approximately double current levels during these epochs. Heightened photosynthesis would have fueled the dynamic and warm climates associated with the flourishing of dinosaur megafauna, influencing carbon cycling and possibly modulating feedback mechanisms within the Earth system. Such robust primary productivity could also have played roles in the sequestration of carbon and shaping the trajectory of Mesozoic ecosystems.
The impact of this study extends beyond paleoenvironmental reconstruction. It introduces a transformative toolset for paleoclimatology, facilitating a more direct and reliable quantification of atmospheric gases from fossilized biomaterials. As Dr. Dingsu Feng from the University of Göttingen, the study’s lead author, articulated, the method “opens up the possibility of using fossilized tooth enamel to investigate the composition of the early Earth’s atmosphere and the productivity of plants at that time.” This advance holds promise for unraveling the complex feedback loops governing paleoclimate variability and refining models of Earth’s climatic past.
Furthermore, the cross-disciplinary nature of this work exemplifies the integration of geochemistry, isotope geology, and paleobiology in addressing long-standing questions about Earth’s history. By harnessing vertebrate fossils hitherto underutilized for climate science, the approach complements marine and sedimentary proxies, offering more nuanced reconstructions that account for terrestrial atmospheric intricacies. This is particularly valuable given that land-based conditions often diverge significantly from marine environments, influencing biotic evolution differently.
Beyond its scientific implications, this research provides a poignant reminder of the narratives encoded in fossil remains. Dinosaurs, through the preservation of their tooth enamel, have inadvertently chronicled Earth’s climatic shifts over an astonishing 150 million years. The metaphor of these ancient creatures as “climate scientists” lends a captivating perspective on how biological archives can inform contemporary environmental challenges. As humanity grapples with anthropogenic CO₂ emissions, understanding the natural variability and consequences of elevated greenhouse gases in the deep past is increasingly crucial.
The study was made possible through funding from the German Research Foundation (DFG) and the VeWA consortium under the auspices of the LOEWE program sponsored by the Hessian Ministry for Science and the Arts. Their support enabled the rigorous laboratory analyses and international collaboration necessary to validate and refine the isotope-based proxy. Moving forward, researchers intend to expand this method to a broader assemblage of vertebrate fossils and chronologies, aiming to construct a more detailed and continuous record of atmospheric evolution through deep time.
The implications of these findings are wide-reaching, extending into climate modeling, ecological forecasting, and even the understanding of mass extinction drivers. By embedding direct terrestrial atmospheric data into climate simulations, scientists can more accurately predict how high-CO₂ worlds functioned and perhaps extrapolate lessons applicable to today’s rapidly changing environment. This makes the fossilized tooth enamel technique a vital advancement not only for paleontology but also for global climate science.
In sum, the convergence of paleontology and geochemical isotopic analysis embodied in this study catalyzes a paradigm shift in reconstructing Earth’s ancient environment. Dinosaur teeth, once solely objects of biological and evolutionary inquiry, are now key archives of atmospheric history, encoding chemical signatures that decode the interplay between greenhouse gases, photosynthesis, and climate over geological timescales. As this novel research avenue matures, it is poised to revolutionize how scientists perceive and model Earth’s climatic saga stretching back hundreds of millions of years.
Subject of Research:
Reconstruction of Mesozoic atmospheric carbon dioxide concentrations using oxygen isotopes in dinosaur tooth enamel.
Article Title:
Mesozoic atmospheric CO2 concentrations reconstructed from dinosaur tooth enamel.
News Publication Date:
4-Aug-2025
Web References:
https://doi.org/10.1073/pnas.2504324122
References:
Dingsu Feng, Thomas Tütken, Eva Maria Griebeler, Daniel Herwartz & Andreas Pack. Mesozoic atmospheric CO₂ concentrations reconstructed from dinosaur tooth enamel. Proceedings of the National Academy of Sciences (PNAS) (2025).
Image Credits:
Credit: Thomas Tütken
Keywords:
Atmospheric science, Earth sciences, Environmental sciences, Climate change, Climate data, Climate systems, Climate variability, Earth climate, Paleoclimatology, Climate modeling, Climatology, Isotopes, Biogeochemistry, Organic geochemistry, Geochemistry, Dinosaurs, Dinosaur fossils
