Nearly 60 Million Years of Climate Change Triggered the Rapid Evolution of Reptiles, Study Finds

The end-Permian extinctions about 250 million years ago and the start of the Triassic period saw the coming out of reptiles who evolved rapidly and whose diversity started exploding, such as varying abilities and traits and body plans that firmly established their lineages to those that still exist today.

These extinct animals flourished at that time before being wiped out by two massive extinctions based on the geologic record, Phys.org reported. Now, a new study led by researchers from Harvard University has rewritten that explanation through a reconstruction of how bodies of ancient reptiles changed during millions of years of climate change.

Existing Theories Explaining Evolution of Reptiles

Researchers use the geological record of the past to study how climate change caused mass extinctions to explore the environmental crises that led to the evolution of many species. One of the theories that explain that Permian-Triassic climatic crises that explain how a series of climate changes due to global warming in the Middle Permian and Middle Triassic affected animals.

During this period, climactic shifts caused two massive extinctions in the history of life that by the end of the Permian period at 261 million years ago, 86% of animal species worldwide had died.

SciTech Daily reported that the end-Permian mass extinctions mark the onset of a new era when reptiles started dominating the vertebrate animals on land. The ancestors of mammals called synapsids dominated land animals at this time. Then during the Triassic Period, reptiles evolved rapidly, creating reptile diversity, which is the key to constructing modern ecosystems.

Scientists believe this happened because competitors went extinct, allowing reptiles to take over habitat and food resources left by synapsids. But a new study reveals that reptiles' rapid evolution and radiation began much earlier, even before the Permian mass extinctions.

Rapid Evolution and Diversity Explosion of Reptiles Linked to Global Warming

The study, titled "Successive Climate Crises in the Deep Past Drove the Early Evolution and Radiation of Reptiles," published in Science Advances, revealed that the rapid evolution and radiation of reptiles were connected to the increasing global temperatures in a long cycle of climatic changes within 60 million years.

Previous studies show that the impact of climate change is often neglected because of limited data on terrestrial vertebrates, as most of the information focuses on the response from marine animals.

Study lead author postdoctoral fellow Tiago R Simões and colleagues from other universities and institutions collaborated to examine early amniotes representing all modern mammals, reptiles, birds, and their closest extinct relatives, EurekAlert! reported. They found that groups of reptiles and mammals were splitting from each other to evolve into their separate species.

Reptiles were rare during the Permian period compared to mammals, but there was a shift in the Triassic period when the former underwent a massive explosion in diversity that led to the appearance of most reptiles, both extinct and still living today.

They created a dataset based on the first-hand collection of over 1,000 fossils from 125 species of synapsids and reptiles from 140 million years before the end-Permian mass extinctions. They analyzed the collected data and combined it with a new dataset with global temperature and data about the adaptive response of animals toward climate change.

They found that periods of fast climatic shifts and global warming are linked to exceptionally high rates of anatomical changes in reptiles as they adapted to the new environment. The process started long before the end-Permian mass extinctions, indicating that the evolution and diversification of reptiles are not because of it as previously thought.

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