Fossilized dinosaur teeth, commonly regarded as mere remnants of ancient creatures, have recently been revealed to hold valuable scientific information. In addition to higher CO2 levels, researchers also discovered that the Earth’s climate during this period was markedly warmer. For example, the teeth of Kaatedocus siberi, a dinosaur related to Diplodocus, showed very negative oxygen levels, indicating extremely high levels of CO2. This anomaly was likely due to the extreme volcanic activity of the time, which caused short-term spikes in CO2 levels, as recorded in the dinosaur teeth. While other techniques could only reconstruct CO2 levels, the analysis of dinosaur teeth provides insights into plant productivity, offering a fuller picture of the ancient world.