A long period of volcanic activity may have set the scene for the dinosaur age.
200 million years ago, a mass extinction event took place on Earth. This was the Triassic mass extinction, and it remains to be one of the largest animal extinctions we know of to date. It's the demarcation line between the Triassic and Jurassic, the era that saw the rise of the dinosaurs. The extinction event vacated a lot of ecological niches that eventually benefited the dinosaurs. Thus, the dinosaurs became the dominant life form on the planet.
Scientists now say it's likely that a million-year-long period of volcanic activity caused the Triassic extinction event. There have been theories that the release of a large amount of carbon dioxide triggered the extinction event, but scientists weren't sure what exactly caused the release of carbon dioxide. Now, it seems that massive and continuous volcanic activity may have been the cause.
A team of scientists have analyzed very old volcanic rocks discovered to be from around 200 million years ago. These rocks were from four different continents that make up the Central Atlantic magmatic province (CAMP). Upon analysis, the team found evidence of massive volcanic eruptions that occurred around the time of the mass extinction event. The researchers looked at a particular sign of volcanic activity: mercury. Volcanic eruptions send trace amounts of mercury into the sky, where the mercury spreads through the atmosphere. The mercury then settles down to the ground and remains in the sediment for millions of years.
Thus, mercury is a good indicator of volcanic activity. If there is a larger amount of mercury in the rocks and sediment, there's a good chance that there had been a volcanic activity at some point in time.
It seems that the dinosaur age had quite the violent start. By volcanic activity, the researchers don't just mean simple volcanic eruptions. Cracks and fissures probably split the Earth's crust up, and it's likely that there were also lava flows and fire fountains. Different areas were active at different times, but periods of eruption probably went on for over a decade in each area. It probably looked like hell on Earth, and life forms in the vicinity of volcanic activity had very little chances of survival.
Large carbon dioxide emissions from the volcanic activity probably had a significant impact on the global climate. Even animals living far away from the eruptions would have felt the effects. The continuous volcanic activity did not only cause a mass extinction event. It also made it difficult for surviving plants to recover.
As of now, it's unclear why the dinosaurs were able to survive the violent eruptions that went on around them. Early amphibians, mammals that looked like reptiles, and huge crocodile-looking animals all perished in the extinction event. The disappearance of these species left dinosaurs in charge of the planet, so to speak. Perhaps soon scientists will be able to determine what it was about dinosaurs that made them survive something that killed many other species. Then, our picture of the dinosaur age will gain another missing piece.
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