Comments on: Synchronous Extinction of North America’s Pleistocene Mammals Placed Within 2,000-Year Time Frame

By: Edgar

Edgar — Thu, 21 Jul 2011 16:03:27 +0000

did these things really exist

By: La Cultura de los Indios Clovis, Extinción de la Megafauna y los Paisajes de Suelos

Mon, 16 Aug 2010 11:38:12 +0000

[...] Tigres con diente de sable en las grandes llanuras americanas. Fuente: Anthropology.net [...]

By: terryt

terryt — Wed, 10 Feb 2010 23:30:14 +0000

” you can easily reconstruct a near completely symmetrical pattern for species still extant, like the wolves, lynx or european brown bear”.

It’s quite possible that the expansion of these species was helped by humans in some way. Perhaps opening ecological niches by disrupting the old ones.

“by now i am rather convinced the impact theory is sensible”.

But you then go on to point out the many problems with this theory. The human-induced extinction theory is much more straightforward. I’m not saying that humans are somehow different to other species in this. The arrival of a new species has been very disruptive to many environments.

By: Tim Jones

Tim Jones — Wed, 10 Feb 2010 21:36:29 +0000

Onyx – many thanks for your prolific commenting today – I’m sorry but I don’t have time to reply in any meaningful manner at the moment as I’m in the process of moving house, so it’ll be a few days yet before I have sufficient time to address the many points you make.

By: onyx

onyx — Wed, 10 Feb 2010 21:26:17 +0000

mm i am now reading the comprison paper about eurasia, fascinating but i dont agree on all, for example the mammoth appears influenced by human settlements along the trekking route. the arctic fox couldnt be in scandinavia at that time because it was 1000 miles within icecovered territory ( you find arctic foxes on the seaside of the northpole iceshelf but not very much inward, bigger mammals he mentioned to have become extinct in western europe (wich had a way higher population density) before in eg. the ukraine, have allways been interpreted as the result of hunting , noot in the least while in some cases (wisent, giant deer) the later (eastern) extinction events have been documented in hunting annals etc. by the former nobles. all in all i would pose the correlation between human habitation and extinction of the megafauna is well established. you can easily reconstruct a near completely symmetrical pattern for species still extant, like the wolves, lynx or european brown bear. allthough a cosmic event like hypothesized would have an impact on diversity overhere as well, at least so are the chances, it’s rather unhelpfull when farfetched assumptions about eg the distribution of arctic foxes are incorporated into this debate. it was the end of an iceage so many species moved (back) to the north and east where it is colder. more fascinating is that a part of the genera that went extinct in NA went extinct worldwide, otoh, if that concerns only the kind of species that suffered from overkill in europe , it is easily explained as the result of our hunting behaviour any huge cosmic event to topple it would ofcourse succeed in exagerating those effects.

By: onyx

onyx — Wed, 10 Feb 2010 20:58:39 +0000

all very interesting and good work, you make wonderfull compilations in the field. i have a few sidenotes, i once read an article on giant sloths for example, that followed their extinction all the way to patagonia, to actually retrace what might have been the last surviving giant sloth, held in captivity and with even patches of skin preserved. as such i am not aware kill sites would be incredibly hard to reconstruct and i wonder if there is an antienvironmental bias in such postulations. also i agree with terry the flue story is one of that kind. ofcourse as yet unproven nevertheless i think it is a ridiculous assumption. for one thing there would have been many flue megaextinctions if things went that way, in the paleological record. also by now i am rather convinced the impact theory is sensible. to explain why animals at higher altitudes survive such an impact, you need to look at the accidentation of the terrain, heat waves tend to pass over holes and pits (ie. valleys), for reference eg look at some of the storys of hiroshima survivors, the survivor closest to the epicentre fell into an only 3 mtr deep pit a few seconds before the explosion. so that shows plasma forms no exception of the rule of thumb in blasts. the puzzle is not complete yet, it is hard to envision why so many avian genera would face total collapse as the result of a blast that many humans (presumable for being in caves) survived. a such blast would btw affect some areas more then others, the pictures in craterseekers comments however show the blast would have taken place rather straight up apparently over new mexico, since ejecti spread from a point of elongation in all directions likewise. ,mere forestfires would not be enough to make many species extinct, animals run for forestfires instinctively, look for water instinctively, and run amazing distances at amazing speeds under the circumstance. it is however possible to assume that the species encountered by early migrants were likewise unadapted to humans as eg marsupials in general (that is no fleeing reaction) combined with a near complete annihilation of the ecosystem as new mexico (when that can be verified wich should be rather easy) suggests, that could be sufficient deathstroke, the battered remnants of humankind would definitily make short work with the easier of prey species, when also breeding grounds etc got decisively destroyed by a mega scale event. questions that rise are: is there a correlation with either water fowl or fowl of the drieer areas, can there be identified layers in the slib deposits (not very wide ones perhaps 10-20 yrs, that are much devoid of floral remnants? did plantspecies related to water ecotopes die out? (a bit hard to check maybe, since most plants don’t have that limited distribution, but it could be done with pollen analyses i imagine) if it changed the floral surrounds over an apreciable time fowl would have a tough time, my conclusion however, already yesterday, is that this is one of the no-panic frauds with science, authoritys just dont want people to know a single unexpected event could whipe out all of north america in mere instants.

By: Dan

Dan — Thu, 31 Dec 2009 01:53:49 +0000

Definitely over hunting. Humans are the worst thing that has ever happened to the world’s diverse ecosystems. Just look outside you window… things have seriously changed… for the worst.

Lucky we have ay other living species at all, anywhere.

By: Tim Jones

Tim Jones — Wed, 16 Dec 2009 21:31:30 +0000

Thanks Terry – I’ll check the Flannery link, and I’m hoping to post a review of some of the recent Australia literature – Dr. Gilbert Price has for example published his thesis “Pleistocene palaeoecology of the eastern Darling Downs”

link=http://eprints.qut.edu.au/16271/

There are 5 papers therein, plus he has some interesting observations from elsewhere – once I’ve finished my current post, I hope to get something written on Australia in the next few days.

By: terryt

terryt — Wed, 16 Dec 2009 21:21:03 +0000

Link for Australian extinctions:

http://uninews.unimelb.edu.au/news/170/

Some will argue that Tim Flannery is biased, but that argument comes mainly from those who believe we are somehow fundamantally different from Paleolithic humans. It’s only modern Europeans who have ever upset any ecologies.

By: terryt

terryt — Wed, 16 Dec 2009 20:52:36 +0000

Thanks for the Amazon link. As I said to Maju, people who live in forest have either become genetically adapted to it, such as Negritos and Pygmies, or have set fire to it, cleared it and farmed it. These ruins belong to a farming culture. So they’d cleared the forest, not lived in it.