New research from the University and international partners has uncovered the mystery of why large Triassic dinosaurs took more than 30 million years to populate the tropics.
For years, palaeontologists have had different theories about why they could find no evidence of large, long-necked, herbivore dinosaurs (sauropodomorphs) living at low latitudes, until at least 30 million years after they first appeared on earth, and 10 to 15 million years after they became abundant at higher latitudes.
Published today in Proceedings of the National Academy of Sciences, the new research suggests a highly unpredictable hot and dry climate, linked with elevated levels of CO2, prevented larger herbivore dinosaurs from inhabiting the area.
The climate, characterised by wet seasons in some years and extreme droughts in others, was punctuated by raging wildfires every few dozen years that reached temperatures of up to 600° Celsius.
The conditions would have made it difficult for abundant vegetation to grow and survive; vegetation that the Triassic predecessors of more well-known Jurassic sauropods (like Brachiosaurus, Diplodocus and Brontosaurus) would have fed on.
Lead-author Dr Jessica Whiteside says:
“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. The fluctuating and harsh climate with widespread wild fires meant that only small two-legged carnivorous dinosaurs, such as Coelophysis, could survive.”