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, leading to the largest creatures to ever walk the earth.
“Large changes in global temperature can have dramatic and variable impacts on biodiversity,” said co-author Professor Stephanie Pierce of Harvard University.
“Here we show rising temperatures during the Permian-Triassic that led to the extinction of many animals, including many of the ancestors of mammals, but also triggered the explosive evolution of others, especially the reptiles that went on to dominate the Triassic,”
Life almost ended 252 million years ago when at least 90 percent of all species were wiped out due to massive volcanic eruptions.
Dinosaurs began to appear about 20 million years later and continued to rule for 165 million years.
“Climate change actually directly triggered the adaptive response of reptiles to help build this huge range of new body plans and the explosion of groups 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 pretty well and survived for millions of years to the present day, and some others that basically disappeared 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.
Scientists traced this back to rising global temperatures, years before any mass extinction events.
They identified enormous anatomical changes that took place in many groups in direct response to major climate changes concentrated between 260 and 230 million years ago.
Dr Simoes described his eight-year study as ‘particularly relevant today’ as temperatures continue to rise.
It combined camera work, CT scans and visits to over 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 arose and how quickly they evolved.
The diagram showed that diversification started about 30 million years before the Permian-Triassic extinction, making it clear that these changes were not triggered by it.
Increases 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 larger cold-blooded animals evolved to be smaller so that 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 disasters 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 off at an alarming rate due to human-induced climate change and habitat encroachment.
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