Waves of volcanic activity 200 million years ago triggered the dawn of the dinosaurs and ended Earth’s Triassic period
The dinosaur era began after a mass extinction event wiped out a large proportion of life on Earth, around 200 million years ago.
And a new study suggests that waves of volcanic activity triggered this mass extinction event.
The findings provide valuable new insights into how dinosaurs evolved on Earth.
Lead researcher Lawrence Percival, a graduate student at the University of Oxford, told MailOnline: ‘During the Triassic all the continents were joined together in one super-continent called Pangea.
‘For most of the time that Pangea existed, the amount of volcanic activity was probably quite similar to today.
But at the end of the Triassic, a huge amount of volcanic activity occurred across North America, South America, Africa, and south-west Europe, which would ultimately lead to the break-up of Pangea and the opening of the Atlantic Ocean.
‘This volcanic activity is thought to have occurred in several mega-eruptions over at least 700,000 years, with episodic eruptions lava flows 100s–1,000s of cubic kilometres in size occurring with times of volcanic quiescence in between.
‘It is not clear precisely how long these mega-eruptions lasted, or how long the gaps between them were.
‘However, based on other studies it is thought that the eruptions would have lasted years to decades, with 100s–1,000s of years in between.’
The Triassic extinction caused hundreds of animals to die out, including many large crocodile-like reptiles and marine invertebrates.
The event also caused huge changes in land vegetation, changing the face of the planet forever.
This mass extinction has long been linked to a large and abrupt release of carbon dioxide into the atmosphere, but the exact source of this has been unknown.
The release of carbon dioxide caused rapid climate change, which many species struggled to adapt to.
By investigating the mercury content of sedimentary rocks deposited during the extinction, the study has found clear links in the timing of volcanic eruptions and the end-Triassic extinction.
Volcanoes give off mercury gas emissions, which spread globally through the atmosphere, before being deposited in sediments.
Because of this, sediments left during a large volcanic event would be expected to have unusually high mercury content.
Mr Percival said: ‘We see high mercury concentrations in end-Triassic sediments from around the world, suggesting a global influence of volcanic gas emissions during the end-Triassic extinction.
‘The mercury concentrations are shown to be in sediments of the same age as hugely extensive lava flows, further strengthening the case for volcanism being the source of this mercury.