Global warming sparked rapid evolution of reptiles, study finds

Harvard study finds reptiles evolved at an astonishing rate to adapt to climate change, reports Aisha Rimi

The rapid evolution of reptiles began much earlier than scientists initially thought (Henry Sharpe)

Global warming led to the rapid evolution of reptiles, causing mass extinctions in many species, a new study by researchers at Harvard University, University of Alberta and North Carolina Museum of Natural History revealed.

The study, published in Sciences Advances, shows the rapid evolution of reptiles began much earlier than scientists initially thought due to nearly 60 million years of global warming and climate change.

According to the study, the extreme climate shift just over 250 million years ago helped establish reptile lineages as one of the most diverse animal groups in the world.

Researchers believed that the explosion of reptile diversity was a result of two of the biggest mass extinction events at the end of the Permian geologic period, which wiped out their competitors, around 261 and 252 million years ago. The latter eliminated 86 per cent of all animal species worldwide.

However, the team of experts have now found that the diversification and physical evolution started tens of millions of years before and were driven by rising global temperatures due to climate change.

Scientists from the Department of Organismic and Evolutionary Biology and the Museum of Comparative Zoology at Harvard University studied the anatomical changes of the reptiles in direct response to major climate shifts between 260 and 230 million years ago (the Permian-Triassic climatic crises) to find patterns.

They measured and scanned reptile fossils between 294 and 237 million years old, and examined 1,000 fossil specimens at 50 research institutions in 20 countries.

For climate data, they used an existing large database of sea surface temperatures based on oxygen isotope data for the last 450 million years.

After examining the changes in body and head size and shape of reptiles directly with climate data, the researchers found that the faster the rate of climate change, the faster the reptiles evolved.

“Large-sized reptiles basically took two routes to deal with these climate shifts,” said Professor Stephanie E. Pierce from Harvard University.

“They either migrated closer to temperate regions or invaded the aquatic world where they didn’t need to worry about overheating because water can absorb heat and maintain its temperature much better than air.”

Tiago R Simões, lead author postdoctoral fellow, added: “This strong association between rising temperatures in the geological past and a biological response by dramatically different groups of reptiles suggests climate change was a key factor in explaining the origin and the explosion of new reptile body plans during the latest Permian and Triassic.”