Megafauna extinction

The accumulation of small heritable changes within populations over time.

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Megafauna extinction

#1  Postby Macdoc » Apr 09, 2017 12:43 am

Was surprised that there was not a lot on this as it is a hard fought issue

Nice overview from NOVA on impact and other hypothesis.



Nano-diamond presence certainly offset the lower iridium concentration .....the lead researcher was overcome at seeing the nano-diamond presence they found in Greenland. Good science.

and newer material points to impact..

Heavy Metal: Comet-driven megafauna extinction?
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Posted March 13, 2017
Roughly 13,000 years ago, large ice-age mammals known as megafauna — horses, camels, mammoths, mastodons and many others — suddenly disappeared in North America. At the same time, a widespread human culture vanished. Mounting scientific evidence suggests this happened in dramatic fashion by a comet or an asteroid slamming into the Earth.


This cliff profile at Arlington Canyon on Santa Rosa Island shows platinium abundance.

New research by UC Santa Barbara geologist James Kennett and colleagues bolsters the argument for indications of such an event, which ushered in a cool period known as the Younger Dryas.

The team had previously identified, from a thin layer at the Younger Dryas Boundary (YDB) dated to 12,800 years ago, a rich assemblage of high-temperature spherules, melt glass, nanodiamonds and other exotic materials, which can be explained only by cosmic impact. Now they can add platinum to the list.


http://www.technology.org/2017/03/13/heavy-metal/

This is North America centric ...not other areas.
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Re: Megafauna extinction

#2  Postby kiore » Apr 09, 2017 3:26 am

Interesting, but the smoking gun remains that megafauna extinctions occurred in Australia much earlier and New Zealand quite recently and both were contemperous to human arrival. The extinctions in the Americas although not so clear also seem to fit this pattern.
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Re: Megafauna extinction

#3  Postby Calilasseia » Apr 09, 2017 1:11 pm

Indeed, the ancestors of the present day Maori knew what it was like to be up close and personal with Moas and Haast's Eagles. Australian aboriginal people 50,000 years ago knew what it was like to face Megalania and Diprotodon, the latter being the largest known marsupial ever to have lived.
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Re: Megafauna extinction

#4  Postby Macdoc » Apr 12, 2017 7:53 am

Interesting, but the smoking gun remains that megafauna extinctions occurred in Australia much earlier and New Zealand quite recently and both were contemperous to human arrival.


One correct ...one not .....New Zealand there is no question of human engendered extinction.

Australia tho ....60% of megafauna were already extinct when human's arrived due in the most part to climate change.
It's cool there may be a reprieve for the thylacine.

Haast's eagles are an interesting top predator. It's considered that the Kea

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evolved colours only under their wings to avoid predation from above.
http://www.teara.govt.nz/en/artwork/988 ... ka-colours.

Diprotodon
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likely was preyed on as big lunch box the way some of South America's extinct animals were,

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I do wonder who might lunch on who with Maglania.

Good images here

https://au.pinterest.com/pin/333688653624869009/
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Re: Megafauna extinction

#5  Postby Macdoc » Nov 15, 2018 12:31 am

Fancy that :whistle:

Impact crater 19 miles wide found beneath Greenland glacier
Crater appears to be result of mile-wide iron meteorite just 12,000 years ago


A huge impact crater has been discovered under a half-mile-thick Greenland ice sheet.

The enormous bowl-shaped dent appears to be the result of a mile-wide iron meteorite slamming into the island at a speed of 12 miles per second as recently as 12,000 years ago.

The impact of the 10bn-tonne space rock would have unleashed 47m times the energy of the Little Boy nuclear bomb dropped on Hiroshima in 1945. It would have melted vast amounts of ice, sending freshwater rushing into the oceans, and blasted rocky debris high into the atmosphere.



more

https://www.theguardian.com/science/201 ... nd-glacier
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Re: Megafauna extinction

#6  Postby The_Piper » Nov 15, 2018 12:53 am

It's time to get serious about asteroid detection. I don't have much hope of that happening.
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