Massive volcanic eruptions set the stage for dinosaurs’ demise

[n2doc]

It's now widely accepted that the impact of an asteroid at Chicxulub in Mexico's Yucatan region finished off any dinosaurs that we don't currently refer to as birds, while triggering a mass extinction that wiped out a lot of other species. But that hasn't ended the debate regarding the dynamics of the extinction event, with other ecological influences getting consideration as contributing to the dinosaurs' vulnerability.

One potential contributor that's hard to overlook is situated in western India: the Deccan Traps. These enormous deposits are built of layer upon layer of volcanic rock, suggesting a series of flood eruptions took place over thousands of years. These eruptions happened suspiciously close to the start of the mass extinction—close enough that some researchers argued that it was the eruptions that killed off the dinosaurs. There was, after all, precedent; the eruptions that formed the Siberian Traps have been blamed for a mass extinction that was so severe, it's known as the The Great Dying.

To help settle the issue, an international team of researchers has gone back and obtained the most precise dates for the eruptions yet. The dates show that the eruptions started nearly a quarter-million years before the onset of the mass extinction but continued for roughly 750,000 years, meaning they spanned the extinction event. This supports the idea that the eruptions helped set the stage for the end of the dinosaurs.

more

http://arstechnica.com/science/2014/12/massive-volcanic-eruptions-set-the-stage-for-dinosaurs-demise/?

[Fortinbras Armstrong]

1. So a combination of the asteroid strike and the volcanoes might have done it?

[Stargazer09]

2. 1 + 1 = 3

The (non-bird) dinosaurs might have been able to survive the Deccan Traps eruption OR the asteroid impact. Both events, in combination, probably sealed their fate.

[Warpy]

3. It might have been 1-2-3

because some researchers have suggested that since so many fossilized remains are in groups in North America, away from the immediate danger of Indian vulcanism (but subject to the global winter it brought) that they were likely suffering from disease, also, and that there were likely few left to see the meteor slam into the Caribbean and eventually finish them off.

[Bearware]

4. I suspect they need to do a better job ruling out multiple impacts first

When I first heard about Chicxulub I immediately tried to figure out if the Deccan Traps were at the antipode. Ran to a globe and was thinking about slant impacts before I did the and tried to remember what the continent was called then. I was never real impressed by the volcanologists exclamations about how big the eruptions were. I just figured out that an event that can put magma in orbit is going to outdo any volcanic event if not cause it all in the first place.

Obviously very accurate dating could decide the arguments but I am not so sure they have ruled out more than one impact separated by a few 100k-1m years. I don't know if the signature of deep ocean impact would be difficult to tease out but then again I don't know
if they are even bothering to look.

I remain skeptical of both the Deccan and Siberian Traps as being other than side effects until they start finding the impacts that have to have been in the ocean basins. Multiple impacts should have been obvious after Comet Shoemaker-Levy 9 (SL9) impacted Jupiter. All you need is an asteroid or comet with 2 or more large weakly held parts.