Image Credit: Dawn Endico
Conventional wisdom tells us that the dinosaurs went extinct as a result of a massive asteroid strike about 65 million years ago, which created the Chicxulub crater in the Northern Yucatan peninsula. The asteroid, with its estimated 10km diameter, caused an environmental catastrophe that wiped out the dinosaurs, and a good deal of other life as well. Of course the problem with conventional wisdom is that it’s not always right. There never really was a handy northwest passage, and the world didn’t turn out to be flat.
The meteor impact may suffer from a similar problem (the problem of being wrong, that is). A new study lead by Gerta Keller (Princeton) and Thierry Adatte (U of Lausanne) suggests that the Chicxulub impact preceded the KT boundary by about 300,000 years. They found no decrease in diversity immediately after the impact line, suggesting that the extinction was caused by something else, like the Deccan Traps volcanic eruptions.
This is pretty interesting stuff. Most theories these days regard the Chicxulub impact as the “straw that broke the camel’s back,” the event that triggered the KT extinction. Many groups, including the dinosaurs, were in fairly serious decline long before KT, a decline usually attributed to the effects of increased volcanic activity (less sunlight, greenhouse effect, etc). If the Chicxulub impact is to be removed from the equation, a reevaluation of volcanism and other factors would seem to be in order.
But the real problem here is that the asteroid impact hypothesis seems to have become conventional wisdom, when from a scientific standpoint, it was never really anything more than one of several plausible options. If there are any geology types lurking around here, I’d love to hear your opinions. What does this new study mean for you? Feel free to comment.