A groundbreaking study conducted by researchers from the universities of Göttingen, Mainz, and Bochum is revolutionizing our understanding of the Earth’s climate during the age of the dinosaurs. By analyzing fossilized dinosaur teeth, scientists have reconstructed atmospheric carbon dioxide concentrations throughout the Mesozoic Era, revealing that CO₂ levels were significantly higher than previously assumed. This breakthrough was made possible through the innovative application of triple oxygen isotope analysis in dinosaur tooth enamel, a method that opens exciting new avenues for paleoclimate research focused on terrestrial vertebrates.
The Mesozoic Era, spanning roughly from 252 to 66 million years ago, has long fascinated scientists seeking to understand ancient climates and ecosystems. Traditionally, attempts to gauge prehistoric atmospheric conditions have relied heavily on marine proxies and soil carbonates, which come with inherent uncertainties. The pioneering technique developed in this study leverages the remarkably stable dental enamel of dinosaur teeth, which preserves the delicate ratios of oxygen isotopes embedded in the air dinosaurs breathed. By extracting this geochemical signature, researchers have obtained unprecedented insights into the dynamic interplay between atmospheric composition and terrestrial vegetation productivity during that period.
Tooth enamel is extraordinarily resilient to diagenetic alteration, making it one of the most reliable biological archives of paleoenvironmental information. The research team examined teeth from various dinosaur species that lived during the Late Jurassic and Late Cretaceous periods, approximately 150 to 66 million years ago, collected from locations across North America, Africa, and Europe. The enamel contains oxygen atoms whose isotopic ratios — specifically among oxygen-16, oxygen-17, and oxygen-18 — shift in response to atmospheric CO₂ concentrations and photosynthetic rates. Careful quantification of these isotopic ratios enables the reconstruction of ancient atmospheric and ecological conditions with remarkable precision.
The data indicated that during the Late Jurassic, some 150 million years ago, atmospheric CO₂ concentrations were approximately four times higher than those of the pre-industrial era. Moving forward in time to the Late Cretaceous, around 73 to 66 million years ago, CO₂ levels were about three times the pre-industrial baseline. These elevated CO₂ concentrations contributed to a planet with significantly enhanced primary productivity, as plants responded to higher carbon availability and warmer global temperatures. The results also suggest that during the Late Cretaceous, spikes in atmospheric CO₂ could be linked to massive volcanic events such as the Deccan Traps eruptions in what is now India, which emitted vast amounts of greenhouse gases.
One of the most fascinating revelations came from the unusual isotope patterns found in the teeth of well-known dinosaur species such as Tyrannosaurus rex and Kaatedocus siberi. These isotopic anomalies may be indicative of short-term fluctuations or peaks in atmospheric CO₂, capturing snapshots of volcanic episodes and their climatic repercussions. The study underscores how dinosaur teeth serve as natural “time capsules,” preserving records of atmospheric chemistry that were previously inaccessible. Embedded within these fossils is a high-resolution geochemical diary of ancient climate and ecosystem dynamics.
This research marks a turning point by introducing the first method that directly assesses terrestrial atmospheric conditions from land vertebrate fossils, rather than relying exclusively on marine sediments or soil proxies. Dr. Dingsu Feng, the study’s lead author from the University of Göttingen’s Department of Geochemistry and Isotope Geology, emphasized the transformational impact of this method. “Our approach provides new insights into the Earth’s past atmosphere and vegetation productivity, which are critical for understanding long-term climate evolution. Dinosaur teeth now allow us to ‘read’ the ancient environment like never before,” Feng stated.
The ability to quantify all three stable oxygen isotopes in fossilized enamel provides a novel mechanism to simultaneously discern atmospheric oxygen composition and infer the photosynthetic vigor of plants during the Mesozoic. This represents a major advancement not only in paleoclimatology but also in paleoecology, allowing scientists to better reconstruct the food web dynamics that sustained the impressive diversity of terrestrial life. Higher primary production likely supported more abundant herbivores, fostering more complex ecosystems with longer and more intricate trophic chains than previously thought.
Professor Eva M. Griebeler, co-author and evolutionary biologist at Johannes Gutenberg University Mainz, highlighted the ecological implications. “Our findings illuminate the magnitude of marine and terrestrial primary productivity, which fundamentally constrains ecosystem structure, species richness, and food chain length.” The interplay between atmospheric CO₂ concentrations, plant photosynthesis, and climate thus emerges as a pivotal driver in shaping ancient biodiversity and ecosystem functionality.
Another striking aspect of the research is the physiological insight gained about dinosaurs through measuring the proportions of oxygen isotopes derived from respiratory air and drinking water. According to JGU paleontologist Professor Thomas Tütken, this dual isotopic information enriches our understanding of dinosaur biology and behavior. “By analyzing these isotopic signatures, we gain clues about how dinosaurs adapted to their environment, their water sources, and even their metabolic processes,” Tütken explained. This opens doors to studying not only extinct reptiles but also other vertebrate species across geological timescales.
The implications of this study extend beyond academic curiosity. Understanding the nuances of Earth’s past greenhouse states and ecosystem responses to elevated CO₂ serves as an invaluable analog for contemporary climate change challenges. It provides a long-term perspective on atmospheric carbon cycling and plant productivity under warm greenhouse conditions, potentially informing models that forecast the future trajectory of Earth’s climate system in the face of anthropogenic emissions.
Funding for this research was provided by the German Research Foundation (DFG) and the VeWa consortium, supported by the LOEWE program under the Hessian Ministry of Science and Research, Arts and Culture. The collaborative effort highlights the importance of interdisciplinary approaches combining geochemistry, paleontology, evolutionary biology, and climate science to unlock Earth’s deep-time climate history.
Published recently in the prestigious journal Proceedings of the National Academy of Sciences (PNAS), this study represents a promising leap forward in paleoclimate reconstructions. The new triple oxygen isotope method applied to fossilized dental enamel is poised to become an indispensable tool for teasing apart the complexities of Phanerozoic atmospheric evolution. As this innovative technique gains traction, the fossilized teeth of ancient vertebrates may provide a treasure trove of atmospheric and ecological data awaiting discovery.
In summary, the application of cutting-edge isotope geochemistry to dinosaur teeth has revealed that Mesozoic atmospheric CO₂ levels were vividly elevated, with primary productivity exceeding modern levels substantially. These findings refine our understanding of ancient Earth systems and highlight the dynamic interactions between volcanism, climate, and life during the age of dinosaurs. Dinosaur teeth, once merely curiosity museum artifacts, now serve as detailed recorders of climatic and environmental shifts from a primordial world.
Subject of Research: Reconstruction of Mesozoic atmospheric CO₂ concentrations and primary productivity using triple oxygen isotope analysis of dinosaur tooth enamel.
Article Title: Mesozoic atmospheric CO2 concentrations reconstructed from dinosaur tooth enamel
News Publication Date: 4-Aug-2025
Web References:
http://dx.doi.org/10.1073/pnas.2504324122
Image Credits: © Naturalis Biodiversity Center
Keywords: Mesozoic Era, dinosaur tooth enamel, oxygen isotopes, atmospheric carbon dioxide, paleoclimate, primary productivity, triple oxygen isotope analysis, fossil geochemistry, dinosaur physiology, Late Jurassic, Late Cretaceous, Deccan Traps, terrestrial vertebrates
