Global warming triggered the age of the dinosaurs, according to new research.
An analysis of more than 1,000 fossils found that climate change started their evolution, rather than mass extinctions.
Rising temperatures caused ancient reptiles to diversify, giving rise to the largest creatures to ever walk the Earth.
“Large changes in global temperature can have dramatic and varied impacts on biodiversity,” said co-author Professor Stephanie Pierce of Harvard University.
“Here we show that rising temperatures during the Permian-Triassic led to the extinction of many animals, including many of the ancestors of mammals, but also caused the explosive evolution of others, especially the reptiles that dominated the Triassic period.”
Life almost came to an end 252 million years ago when at least 90 percent of all species were wiped out due to massive volcanic eruptions.
The dinosaurs began to emerge about 20 million years later and ruled for 165 million years.
“Climate change actually directly triggered the adaptive response of reptiles to help build this wide range of new body plans and group explosions that we see in the Triassic,” said lead author Dr Tiago Simoes.
“Basically, rising global temperatures triggered all these different morphological experiments, some that worked quite well and survived for millions of years to the present day, and some that basically died out a few million years later.”
The study, published in the journal Science Advances, reveals for the first time how reptile bodies changed in response to millions of years of climate change.
The researchers traced this back to rising global temperatures, years before any mass extinction event.
They identified major anatomical alterations that took place in many groups in direct response to major climatic changes concentrated between 260 and 230 million years ago.
Dr. Simoes described his eight-year study as “especially relevant today” as temperatures continue to rise.
He combined camera work, CT scans, and visits to more than 50 different museums in more than 20 countries with global temperature data from millions of years ago.
State-of-the-art statistical techniques produced an “evolutionary time tree” that revealed how early reptiles were related to each other, when their lineages first originated, and how fast they were evolving.
The diagram showed that diversification began about 30 million years before the Permian-Triassic extinction event, making it clear that these changes were not caused by it.
The rise in global temperatures began about 270 million years ago and lasted until at least 240 million years ago.
They were followed by rapid body changes in most reptilian lineages. For example, some of the largest cold-blooded animals evolved to become smaller so they could cool down more easily, while others evolved to live in water for the same effect.
The researchers now plan to investigate the impact of environmental catastrophes on the evolution of organisms with abundant modern diversity, such as the major groups of lizards and snakes.
Earth’s sixth mass extinction has already begun, with animals dying at an alarming rate due to human-caused climate change and habitat incursions.
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