The asteroid is innocent

[AstralTraveller]

Recently it has been suggested that a asteroid or comet struck the Laurentide (north America) icesheet about 12,900 years ago and that this contributed to megafaunal extinctions and the Younger Dryas cooling (Firestone et al PNAS 104:41 pg 16016). While the evidence for an impact seems sound (at least at first glance) its effect on the megafauna has been questioned. Research to be published in PNAS this week reports on the identification of wooly mammoth DNA in Alaskan permafrost dated to between 7,600 to 10,500 years old. This means that mammoths existed for 2000 to 5000 years after the impact. It also shows that they survived long after the arrival of humans, thus casting doubt on the over-hunting hypothesis.

http://media.uow.edu.au/news/UOW070684.html

[renormalised]

It's not going to kill off 100% of all the animals, so those mammoths descended from remnant populations after the impact is no big deal. But it would've killed off the majority of most of the animals. One thing it did do and that's wiped out the Clovis Point people. After the initial phase of the Younger Dryas, they disappeared from the scene...or at least the culture did.

It also ultimately depends on the impact itself. Sometimes these events happen and not much happens. Other times they happen and all hell breaks loose.

[AstralTraveller]

I think that surviving for 2000 years after the impact puts it in the clear. The veg would have recovered and the population should be on the rise.

[renormalised]

Depends on what else is happening. You never know...genetic bottleneck = possible disease vulnerability, inbreeding etc. Much like the Cheetah, today.

Their population might not have been as healthy as it would otherwise seem. Funny that the respreading of the grasslands should've been great for the mammoths, since they're mostly grazers of grasses. Whereas, the mastodons were mostly browsers and would've been affected more so by the loss of the trees.

[JimmyH155]

Isn't it amazing. They have found evidence of mammoths living as close as 6,000 years ago on Wrangel Island, which is 100 miles off the Siberian coast. :D
Pretty desolate there though:sadeyes:

[renormalised]

Is now....wasn't then. It was grassland with some open forest. Actually, during the last Ice Age, most of Siberia was ice free. It was cold, but it wasn't under an icecap, like what most people think. The really thick ice was actually over Europe, especially Scandinavia. The northern reaches of the Asian landmass were iced over but once you got inland far enough, the ice was confined to glaciers in the high mountains. Mind you, the snow/ice line at the time was much lower than it is now. Glaciers came down to within a few hundred metres of sea level in those mountains.

Those mammoths on Wrangel Is were pygmy mammoths. Dwarfism caused by isolation on a small landmass. Over time, they grew smaller in order to better accommodate themselves into their habitat.

[JimmyH155]

thanks for that, Carl. I got interested in Wrangel Island after reading a fascinating book about the last (and most badly organised) Canadian Arctic expedition, where the ship "Karluck" sunk near the Island, AND THE GRIPPING STORY OF HOW THE CREW REACHED THE ISLAND, AND HOW THE cAPTAIN OF THE SHIP SET OUT WITH ONE iNNUIT COMPANION and managed to reach Siberia, and eventually rescue the crew. Fabulous reading. Book called "The ice master" by Jennifer Niven. :P:D:D