A huge volcano erupted 233 million years ago, releasing carbon dioxide, methane, and water vapor into the atmosphere. This series of violent eruptions, which we now know off the west coast of Canada, caused a huge increase in global warming. Our new research reveals that this was a planet-changing mass extinction event that killed many dominant tetrapods and announced the extinction of dinosaurs.
The best mass extinction occurred 66 million years ago at the end of the Cretaceous period. This is when dinosaurs, pterosaurs, sea reptiles and ammonites all died. The event was mainly caused by the impact of a giant asteroid that blackened the sunlight and caused darkness and cooling, followed by the oceans and other large-scale disturbances of the atmosphere.
Geologists and paleontologists agree on a roster of five such events, the last of which was the end of Cretaceous mass extinction. So our new discovery of a previously unknown mass extinction seems unexpected. And yet this phenomenon, called corneal pleural episodes (CPE), seems to have affected many species, like a giant planet. The ecosystems on Earth and at sea were drastically changed as the planet became warmer and drier.
Sturstock / Amtjack
On the ground, this has led to profound changes in plants and vegetarians. In turn, dinosaurs were given their chance, with a decline in dominant plant-eating tetrapods such as rhinosaurs and disinod onts.
Dinosaurs originated about 15 million years ago and our new study shows that, as a result of CPE, they expanded rapidly in the next 10 million to 15 million years and became the dominant species in terrestrial ecosystems. The CPE launched the “Dinosaur Age” which lasted for a further 165 million years.
It wasn’t just the dinosaurs that had to be put on their feet. Many modern tetrapod groups, such as turtles, lizards, crocodiles and mammals, date back to the time of this newly discovered revolution.
Following the links
The incident was first reported independently in the 1980s. But it was thought to be limited to Europe. First, geologists in Germany, Switzerland, and Italy recognized a large turnover in marine animals about 232 million years ago, in what they called the Ringraben event.
Read more: Five sets extinct – and what we can learn from them today about the planet
Then in 1986, I independently recognized this as a global scale turnover in tetrapods and ammonites. But at the time, the dating age was much weaker than it is now and it was impossible to be sure if the two were the same phenomenon.
Fragments of jigsaws fell to the ground when an episode of humid weather of about 1 million years was recognized by geologists Mike Sims and Alastair Raphael in the UK and parts of Europe. Geologist Jacopo Dal Corso then observed a coincidence with the peak of Virengalia basalt eruptions during the CPE period.
Virengalia is a term that geologists give to a narrow tectonic plate that connects the west coast of the North American continent, and Van Nakuvar and north of Seattle.
British Columbia University (EOAS)
Eventually, in a review of evidence of triassic-aged rocks, the signature of the CPE was found – not only in Europe, but also in South America, North America, Australia, Australia and Asia. This was far from being just a Europe-event. It was global.
The volcano erupted
The huge Rangelia eruption sent carbon dioxide, methane and water vapor into the atmosphere, leading to global warming and increased precipitation. There were as many as five pulses of eruption with warming peaks 233 million years ago. Acid rain erupted in such a way that volcanic gases dissolved in rainwater and could dissolve the earth into dilute acid. Even the shallow oceans became acidic.
Extreme temperatures kill tropical plants and animals on land with tropical and acid rain, while sea acidification attacks all marine organisms from carbonate skeletons. It stripped the oceans and the land surface. Life may have started to get better, but when the eruptions stopped, the temperature remained high when the tropical rains stopped. This is the reason why the soil on which the dinosaurs developed later dried up.
The most extraordinary was the re-casting of the marine carbonate factory. This is the global mechanism by which calcium carbonate forms a large thickness of lime and provides materials for organisms such as corals and mollusks to form its shell. The CPE introduced modern coral reefs, as well as many modern groups of plankton, suggesting profound changes in marine chemistry.
De Bonadona / Muse, Trento, Author provided
C.P.E. Earlier the main source of carbonate in the oceans came from microbial ecosystems such as mud mounds influenced by limestone on the beds of continents. But after CPE, it was driven by coral reefs and plankton, where new groups of microorganisms such as dinoflagellates appeared and bloomed. This profound switch into the basic chemical cycle in the oceans marks the beginning of modern marine ecosystems.
And it’s going to be an important lesson in how we help our planet recover from climate change. Geologists need to investigate the details of the activity of the Varangelia volcano and understand how these frequent eruptions caused the climate to change and changed the Earth’s ecosystems. Many volcanic-induced masses have disappeared in the history of the earth and physical disturbances such as global warming, acid rain and sea acidification are one of the challenges we are facing today.
Paleontologists will need to work more closely on data from records of marine and continental fossils. This will help us understand what the crisis was like in terms of the loss of biodiversity, but also in exploring how the planet came back.
