According to recent research, climate change, not the mass extinction of other species, initiated the age of dinosaurs about 250 million years ago.
The diversity boom of reptiles during the end of the Permian and the beginning of the Triassic periods, about 261 and 252 million years ago, has been related to two of the largest mass extinction events.
It was believed that these events eliminated the competition for reptiles, allowing them to grow and diversity in terms of their talents, body plans, and characteristics.
Nonetheless, a new study by Harvard researchers refutes this notion by reconstructing how the anatomy of ancient reptiles evolved and comparing it to climate change over millions of years.
It demonstrates that not only did the diversification of reptiles begin years before these catastrophic extinction events, but that it was also directly influenced by what caused them in the first place: rising global temperatures as a result of climate change.
Tiago R. Simes, a postdoctoral fellow in the Pierce lab at Harvard University and the study’s principal author, stated, “We believe there are two significant mechanisms at play.”
“Not just this open ecological opportunity that several scientists have always considered, but also something that no one has ever thought of before.
Climate change directly spurred the adaptive response of reptiles, which aided in the development of a huge array of new body designs and the proliferation of Triassic groups.
Rising global temperatures generated a variety of morphological experiments, some of which worked pretty well and have persisted for millions of years to the present day, while others disappeared a few million years later.
The findings are based on photographs, scans, and analyses of more than 1,000 fossilized reptiles housed in more than 50 museums worldwide.
Using this information, the researchers constructed an “evolutionary time tree” depicting how early reptiles, including the ancestors of crocodiles and dinosaurs, were connected, when their lineages formed, and how quickly they were changing.
They next examined links between this data and global temperature data from millions of years ago.
They discovered that the diversification of reptile body designs began approximately 30 million years before the Permian-Triassic extinction, proving that these alterations were not caused by the event as previously believed.
In addition, the rises in global temperatures that began approximately 270 million years ago and lasted until at least 240 million years ago were accompanied by rapid morphological changes in the majority of reptile lineages.
For example, some of the larger cold-blooded creatures have evolved to become smaller so that they can cool down more quickly, while others have adapted to aquatic life for the same reason.
The second group contained some of the oddest extinct reptiles, such as a large, long-necked aquatic reptile that was previously believed to be the Loch Ness monster, a tiny chameleon-like creature with a bird-like skull and beak, and a gliding reptile like a gecko with wings.
It also contains the ancestors of living reptiles such as turtles and crocodiles.
Smaller reptiles, which spawned the earliest lizards and tuataras, followed a different evolutionary path than their larger relatives. Their evolutionary rates slowed down and stabilized in response to the rising temperatures.
The researchers hypothesize that this was because small-bodied reptiles were already better acclimated to the rising heat, as they can remove heat from their bodies more efficiently than larger reptiles when global temperatures rose rapidly.
As temperatures continue to rise, the findings have contemporary relevance.
The rate of carbon dioxide produced into the atmosphere today is approximately nine times greater than it was during the Permian-Triassic global extinction 252 million years ago.
Some animals have already begun morphing in response to weather-related pressures.
According to recent research conducted by the University of Sheffield, birds are adjusting to global warming by growing larger beaks, which serve to keep them cool.
Meanwhile, Australian scientists showed that elephants and rabbits are adapting by sprouting larger ears, like Dumbo and Bugs Bunny.
Elephants utilize them as fans, while rabbits cool themselves by contracting a vast network of blood vessels.
According to co-author Professor Stephanie Pierce of Harvard University in the United States, “major changes in global temperature may have substantial and variable effects on biodiversity.”
Rising temperatures during the Permian-Triassic era caused the extinction of numerous species, including many of the progenitors of mammals, but also encouraged the rapid evolution of others, particularly the reptiles that went on to dominate the Triassic period.
Now, the researchers intend to explore the effect of environmental disasters on the evolution of creatures with great current diversity, such as the most diverse families of lizards and snakes.
