Dinosaur Teeth Reveals They Consumed Higher Carbon Dioxide Levels Than Today: Study
Fossils often serve as a time capsule, aiding researchers in understanding past events. In a study published in Proceedings of the National Academy of Sciences (PNAS), a team of researchers has used a new kind of fossil to get a glimpse of the past. The fossil in question is dinosaur teeth. The study focuses on teeth from the Mesozoic Era, which lasted from 252 million to 66 million years ago, when, as per past examinations, the environment was hot and fertile. Researchers examined samples from museums all across Europe. The investigation helped them understand the carbon dioxide levels and plant productivity that existed back then. It is the first time insights about these facets have come forth with such detail from this particular period.
How does a Dinosaur Tooth Hold the Climatic Record?
When an animal drinks and breathes, a mixture of oxygen atoms gets stored inside their enamel, according to Earth. The arrangement and features of these oxygen atoms reflect the condition of the atmosphere in that specific period. The enamel forms the outer coat of a dinosaur's tooth, and is more rigid than bone. It is so hardy that no factor can allegedly cause a chemical change in its components. Hence, the oxygen atoms have remained well-preserved inside the enamel for around 250 million years. Analysis of these atoms using a unique laboratory technique allowed experts to gather insights with never-before-seen accuracy.
Examinations Undertaken by the Team
The laboratory technique separated the three natural oxygen isotopes found in the enamel into several parts with per-million accuracy. In the study, researchers focused on the triple oxygen isotope, also called oxygen-17, according to Science Alert. Past examinations indicated that when the isotope rises in atmospheric oxygen, carbon dioxide levels get elevated. On the other hand, when the quantity of isotopes decreases, global plant growth increases. Animals essentially absorb this isotope from their atmosphere through drinking and breathing, and it gets stored in their enamel. Isotope levels at different periods showcase how the atmosphere changed across time. Experts in the past have investigated levels of this isotope in Cenozoic mammal teeth to reconstruct their atmosphere, but the study is the first time this examination has been done on dinosaur teeth.
Results of the Examination
Triple oxygen isotope levels in dinosaur teeth indicated that there was 1,200 parts per million (ppm) of carbon dioxide (CO₂) in the late Jurassic environment, and by the time the Late Cretaceous arrived, the quantity dipped to near 750 ppm. These readings are way above the pre-industrial benchmark of 280 ppm. In the teeth of Tyrannosaurus rex and Kaatedocus siberi, there were differing patterns of oxygen isotope levels, which could mean that, for short periods, there could have been CO₂ spikes in certain regions due to volcanic gas releases. Researchers incorporated climate models and also determined that plant production in the Mesozoic Era was double the modern output.
The overgrowth could be a reason behind the dip in carbon dioxide, as more plants meant more photosynthesis, which released excess oxygen and suppressed carbon dioxide. Professor Eva M. Griebeler of Mainz claims that the data on plant production could provide never-before-seen insights into marine and terrestrial food webs from the Mesozoic Era. The readings also align with studies of past eruptions in the Deccan Traps, where allegedly 200,000 gigatons of CO₂ were released due to volcanic events.
"Our teeth samples offer a previously missing land based puzzle piece," Dr. Dingsu Feng added. The alignment could help experts further understand how life responded to the volcanic event. Researchers are now examining enamel from early mammals of the Paleocene Eocene Thermal Maximum. If the readings align with the known assertions, then more dinosaur teeth fossils will be involved to get new perspectives on past events.