Scientists have long been baffled by a lack of Triassic period fossils from large, herbivorous dinosaurs known as sauropods near the equator. A new study offers some illumination: It suggests a hot, unpredictable climate and high carbon dioxide levels kept some of the world's first dinosaurs away—and may shed light on our own issues with climate change. Researchers first analyzed ancient sedimentary rocks in New Mexico, which would have been much closer to the equator as part of the supercontinent Pangea some 215 million years ago, reports LiveScience. In separating carbon isotopes from fossilized organic matter, they identified significant and rapid changes to the ecosystem and atmospheric CO2 levels—which were four to six times those of today. Pollen and spores suggested available plants varied in quantity based on the frequent changes, while fossil charcoal showed evidence of wildfires every few dozen years that wreaked havoc on vegetation.
The combined factors suggest an environment too unstable for sauropods until about 30 million years later, though small, carnivorous dinosaurs did populate the area. "The conditions would have been something similar to the arid Western United States today, although there would have been trees and smaller plants near streams and rivers and forests during humid times," study author Jessica Whiteside explains in a press release. Eerily, she writes at the Conversation that "rapid climate swings and extremes of drought and intense heat driven by increasing atmospheric CO2 levels have as much ability to alter the vegetation supporting modern human populations as they did for the large plant-eating dinosaurs in the Triassic." Whiteside adds we can expect "profound challenges to human sustainability in the future if we experience the high CO2 conditions predicted to develop in the coming 100 to 200 years." (Scientists made an incredible discovery inside "crap" dino fossils.)