Scientists have been long puzzled by the plant-eating dinosaurs’ preference for higher altitudes during the Triassic, long before they turned into the planet’s most widespread animals. For some mysterious reason none of them settled at the tropics at that time.
Nevertheless, some paleontologists claim that they have solved the riddle. The dinosaurs migrated northward and settled at higher altitudes while staying away from the equator for millions of years because of an unstable climate. In the equatorial regions, the air was so dense and saturated with carbon dioxide that no dinosaur could possibly survive in those conditions, scientists explained.
A paper on the new findings was published June 15 in the journal PNAS.
According to previous studies, what we know today to be dinosaurs first appeared in mid-Triassic, which is nearly 230 million years ago. But no fossils of herbivorous dinosaurs were found at the equator, including in the famous fossil site Ghost Ranch in New Mexico, which was located a little north from equator at that moment. Instead plenty of dinosaur remains appeared on both sides of the equator.
“For several decades, researchers noticed [that] large, plant-eating dinosaurs seemed to be much more common at high latitudes during the Triassic,”
said Jessica Whiteside, the lead author of the findings.
She also added that scientists noticed that plant-eating dinosaur remains were missing from the tropics, but they did find fossils of small carnivorous dinosaurs.
Ms. Whiteside’s team went to Ghost Ranch, took some rock samples and crashed them to count carbon and oxygen isotopes. Later they could speculate over climate conditions and plant life in the area. Researchers estimate that New Mexico’s atmosphere during mid-Triassic had so much carbon dioxide in it that made life almost unbearable especially for large herbivores.
Scientists found levels of carbon dioxide that were four to six times higher than in our days. Subsequently, the team believes that too much carbon dioxide retained heat and fueled wildfire, leading to the disappearance of numerous species of plants and plant eating dinosaurs that relied on those plants to feed.
Ms. Whiteside argues that extreme heat, severe droughts, and climate shifts left plant-eating dinosaurs without their primary food source. So they so went extinct at the tropics. And they did not come back for more than 10 million years.
Ms. Whiteside added that we should learn from the fate of dinosaurs when carbon dioxide reaches alarming levels. The researcher was concerned that we may share the same fate if we fail to tackle climate change shifts in the next 100 years.
Image Source: Dinosaurusi