For the last 30 years, the prevailing theory has been that an asteroid, around six miles across, hit the Yucatan peninsula 65 million years ago, throwing debris into the atmosphere, blocking the sun and chilling the planet to the point that nearly half of all species went extinct. Ah but here's the rub, recent discoveries can not tie a single extinction event to the Yucatan / Chicxulub event.
Evidence is accumulating that it wasn't an asteroid that did the beasts in, but volcanoes. Volcanic events lasting almost 10,000 years, laying down miles deep deposits and throwing more that 10 times the amount of more climate-changing emissions into the atmosphere than the asteroid impact. Also supporting the volcanic theory is fossil evidence from Texas and Mexico that most of the species extinctions coincided with the final pulse of eruptions, not with the asteroid impact, which may have occurred approximately 300,000 years earlier.
There is even evidence that dinosaurs lived in India (where the massive eruptions occurred) right up to the last phase of the volcanic event - but not afterward.
The argument against of course is that there is volcanism, there was volcanism and there always will be.... so volcanism alone is not in and of itself unique. However the asteroid impact was and therefor can not be dismissed out of hand.
<- read more in Wired ->
Evidence is accumulating that it wasn't an asteroid that did the beasts in, but volcanoes. Volcanic events lasting almost 10,000 years, laying down miles deep deposits and throwing more that 10 times the amount of more climate-changing emissions into the atmosphere than the asteroid impact. Also supporting the volcanic theory is fossil evidence from Texas and Mexico that most of the species extinctions coincided with the final pulse of eruptions, not with the asteroid impact, which may have occurred approximately 300,000 years earlier.
There is even evidence that dinosaurs lived in India (where the massive eruptions occurred) right up to the last phase of the volcanic event - but not afterward.
The argument against of course is that there is volcanism, there was volcanism and there always will be.... so volcanism alone is not in and of itself unique. However the asteroid impact was and therefor can not be dismissed out of hand.
<- read more in Wired ->
2 comments:
I've heard about this idea for a few years,and tend to support those who feel that the best answer is a combination of the events (The excessive volcanism had killed off many species and weakened others, with the Chicxulub event as the coup de gras.)
The impact of the volcanoes is fascinating, but doesn't change the fact that there were some dinosaurs living right up the the Chicxulub event, and no non-bird dinosaurs after the event.
That is what I thought Dave, but this article is pretty clear on the point that there were no extinction events ascribed to the Chicxulub event. That to me would be pretty damn important....
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