Previous research has shown that the largest dinosaurs to ever roam the Earth steered clear of the tropics. Paleontologists have long wondered why, and now, a new study suggests that climate change may be the one to blame.
Early dinosaurs of the mid-Triassic period (the first 30 million years that dinosaurs ruled the land) lived comfortably at the north and south end of the continent, but avoided the equator thanks to radical changes in climate due to greenhouse gases. High levels of carbon dioxide found in the atmosphere are believed to have made it impossible for large prehistoric creatures to live at low latitudes.
Most researches have suspect for a while that climate was probably the reason why no bones belonging to large dinosaurs have been found at low latitudes, however they didn’t have much in the way of proof until recently.
The study was funded by the National Science Foundation, conducted by an international team of experts, and published earlier this week, on Monday (June 15, 2015), in the journal PNAS.
Randall Irmis, co-author, curator of paleontology at the Natural History Museum of Utah and assistant professor at the University of Utah, gave a statement explaining that “Our data suggest it was not a fun place. It was a time of climate extremes that went back and forth unpredictably and large, warm-blooded dinosaurian herbivores weren’t able to exist nearer to the equator – there was not enough dependable plant food”.
He went of to inform that drought, intense heat and spontaneous fires were responsible for destroying plants, which made it an unfriendly habitat for large herbivores as they required large amounts of food.
In an effort to gather proof, co-authors Randall Irmis and Dr. Jessica Whiteside, a paleoclimatologist at the University of Southampton, went to Ghost Ranch in New Mexico and collected rock samples. They studied them for nine (9) years and were able to gather data on climate conditions, atmospheric makeup and plant life from more than 200 million years ago by crushing the rocks and counting the isotopes of oxygen and carbon.
Dr. Whiteside informs that the equator had carbon dioxide levels that were four to six (4 to 6) times higher than those found today in the atmosphere. She says that the conditions would have been similar to that of today’s arid western United States. One key difference is that there would have been some small plants and trees close to streams and rivers. She even thinks there would have been forests during humid periods of time.
The research duo states that the study is the first of its kind and establishes an undeniable link between climate change and ecosystem evolution. They stress that the findings suggest there are very real consequences for the modern-day world it the planet enters the high CO2 conditions that have been predicted by climate scientists.
Dr. Whiteside shares that the only dinosaur fossils found in the tropics belong to small sized carnivores such as the Coelophysis. The more common creatures found in the area were reptiles known as Pseudosuchian archosaurs, the ancestors of crocodiles and alligators.