Dinosaurs May Have Been Wiped Out By Two Separate Extinction Events
The question of what caused the mass extinction of dinosaurs 65 million years ago has remained a mystery for centuries. Mexico’s Chicxulub crater points to a massive asteroid strike that devastated the Earth. The K-T extinction event [Cretaceous (K) and Tertiary (T) periods] is widely believed to be the culprit, but now scientists believe that this wasn’t the only worldwide event that led to the extinction of dinosaurs.
There were a series of devastating volcanic eruptions around what is now known as India about 150,000 years before the massive asteroid hit the Earth. This is believed to have caused a worldwide climate change that affected a majority of dinosaurs, plants, insects, and other forms of life. The volcanic eruptions changed the temperature of the world’s oceans to about 7 °C, or 44.6 °F, by depleting the ocean’s depths of oxygen and creating lethal anoxic conditions.
Thomas Tobin, the head of a research team at the University of Washington, has discovered sedimentary rocks on Seymour Island off the coast of Antarctica. This discovery points to new evidence of what happened over 65 million years ago. One layer of the sedimentary rock shows an initial extinction event occurring some 150,000 years before the asteroid hit, which is about the same time as the Indian volcanic eruptions. This new evidence suggests about half of the world’s species were killed off in this first wave, most likely around India, and then the Chicxulub asteroid struck the Earth, killing off many species which had survived the first calamity.