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> And only in the last decade did we establish that another, only 12800 years ago, killed off most American megafauna, and much of nascent American cultural dev

> And only in the last decade did we establish that another, only 12800 years ago, killed off most American megafauna, and much of nascent American cultural development. Could you provide a source for that? Everything I'm finding says this is anything but well-established.

ncmncm 6y ago
http://deadlyvoyager.net/References/ http://deadlyvoyager.net/References/ A layer all over the Americas and out to Syria, Chile, and South Africa, right at 12800 years ago, the start of the Younger Dryas freeze that lasted 1200+ years. It is packed with soot from hemisphere-wide wildfires, melt glasses, hexagonal nanodiamonds, and elevated platinum. Bones of American mammoths, mastodons, horses, camels, giant sloths, dire wolves, glyptodonts, and many others appear only up to the layer. Also, all Clovis culture artifacts end immediately below the layer. Current hypothesis is a broken-up comet and multiple Tunguska-style airbursts scattered over a wide area. (The only naysayers, last published in 2017, cite one study that sampled only one site, and not at the layer in question.)
Eliezer 6y ago
Doesn't look truish based on this: https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesi... but I retain some small probability that the jury is still out.
- ncmncm 6y ago
  Imagine Wikipedia being wrong... The opposition gave up publishing in 2017. There is a great Nova episode on Youtube where they sponsored a trip to Greenland to collect ice samples from that period, and had a camera in the room when the first SEM images came up. It's all-over nanodiamonds. https://www.pbs.org/wgbh/nova/video/megabeasts-sudden-death/ https://www.pbs.org/wgbh/nova/video/megabeasts-sudden-death/ That was in, what, 2010? Makes me wonder what motivated everything published against, since.

ncmncm 6y ago

http://deadlyvoyager.net/References/ http://deadlyvoyager.net/References/ A layer all over the Americas and out to Syria, Chile, and South Africa, right at 12800 years ago, the start of the Younger Dryas freeze that lasted 1200+ years. It is packed with soot from hemisphere-wide wildfires, melt glasses, hexagonal nanodiamonds, and elevated platinum. Bones of American mammoths, mastodons, horses, camels, giant sloths, dire wolves, glyptodonts, and many others appear only up to the layer. Also, all Clovis culture artifacts end immediately below the layer. Current hypothesis is a broken-up comet and multiple Tunguska-style airbursts scattered over a wide area. (The only naysayers, last published in 2017, cite one study that sampled only one site, and not at the layer in question.)

Eliezer 6y ago

Doesn't look truish based on this: https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesi... but I retain some small probability that the jury is still out.

ncmncm 6y ago
Imagine Wikipedia being wrong... The opposition gave up publishing in 2017. There is a great Nova episode on Youtube where they sponsored a trip to Greenland to collect ice samples from that period, and had a camera in the room when the first SEM images came up. It's all-over nanodiamonds. https://www.pbs.org/wgbh/nova/video/megabeasts-sudden-death/ https://www.pbs.org/wgbh/nova/video/megabeasts-sudden-death/ That was in, what, 2010? Makes me wonder what motivated everything published against, since.