Dinosaurs dominance helped by mass volcanism
Immense volcanic activity helped the dinosaurs rise to prominence some 200 million years ago, a study suggests.Dinosaurs were the dominant vertebrates on land for some 135 million years.
While it is widely accepted that an asteroid or comet wiped them out, there has been less agreement on the factors which led to their ascendancy. Research in PNAS journal suggests volcanic eruptions changed the climate, causing a mass extinction that wiped out the dinosaurs main competitors. The scientific paper, by researchers from the US and Taiwan, looked at several lines of evidence such as the remains of plant wax and wood from sedimentary rocks interbedded with lava flows. From these, they were able to extract vital data about the climate at this time.
The lava flows are dated to the end-Triassic extinction, 201.4 million years ago, which wiped out 50% of tetrapods (four-limbed animals) on land, 50% of terrestrial plants and 20% of marine families. The scientists examined how two different isotopes (or forms) of carbon fluctuated during these volcanic eruptions. They found that the “heavy” form of carbon was depleted relative to the “light” form.