Volcanoes helped dinosaurs rule the Earth, say scientists
Massive eruptions triggered by separation of tectonic plates killed off dominant crurotarsans, fossil evidence shows
Ian Sample, science correspondent guardian.co.uk,
Monday 22 March 2010 19.04 GMT
Volcanoes that spewed out lava and noxious gases for more than half a million years paved the way for dinosaurs to rule the Earth by wiping out their competitors, scientists say.
The environmental devastation wrought by relentless volcanic activity at the end of the Triassic period 200m years ago laid waste to animal species that lived alongside the early dinosaurs, giving them the upper hand in the Jurassic period that followed.
Before the rise of the dinosaurs, the animal world was dominated by crurotarsans, ancient relatives of modern crocodiles. But as their populations crashed, early therapods, the group of dinosaurs that includes all meat-eating species from Velociraptor to Tyrannosaurus rex, gained ground and thrived.
More than 200m years ago, most of the land on Earth was locked up in the Pangea supercontinent, but this broke apart when the North American and African tectonic plates parted. The separation of the plates created a basin that became the Atlantic ocean and opened up fissures in the Earth's crust, triggering volcanic eruptions that lasted for 600,000 years.
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http://www.guardian.co.uk/science/2010/mar/22/volcanoes-helped-dinosaurs-rule-earth