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Author Topic:   Overkill, Overchill, Overill? Megafaunal extinction causes
gunslinger05
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Message 61 of 64 (75104)
12-25-2003 12:51 PM


this is just a general response to the whole overkill hypothesis:
1. It doesn't make logical sense. All anthropological observation of extant hunter-gatherer peoples shows us that they do not slaughter any population of animals (even the really easy to kill ones) in the numbers that the overkill theory implies , nor do they do it just non-chalantly, like we do for sport. Check any anthropological articles on hunter-gatherers and you'll no doubt see that this is true.
2. The megafauna, North American or in general, were just that: megafauna. It means they were huge. Now, the earliest Americans were not like us, they didn't have high-powered rifles that would enable them to take down an animal with a single kill-shot to the head. At best, they had bows and arrows and spear-throwers, and the very least, lances and axes. It's not exactly the smartest endeavor to go after something the size of an elephant or larger with that kind of weaponry on a significantly repeated basis. Maybe every once and a while, but not all the time.
3. Most large "kill sites" of megafaune in North America and Siberia are found near the arctic circle, in northern Siberia and Alaska. Here, the bones of thousands of mammoths and other megafauna have been found buried deep in muck and other organic debris; though no bones found so far show any markings that would imply human butchering of the carcasses. In fact, most of the ivory sold throughout the middle 1800s through the early 1900s came from "islands" found north of Siberia that were made up almost entirely of fossilized mammoth bones, sand, and mud. This alone implies some sort of climactic activity is responsible...unless of course early hunter-gatherers would go to the trouble of killing and butchering the animals before towing them several dozens to hundreds of miles offshore to dump them in the freezing arctic waters...
What do these three points imply? They imply that while the early Native Americans may have hunted done some megafauna, they more than likely did not bring about their extinction. Also, recent comparions of fossilized megafauna (focusing on morphology and what genetic material can be reclaimed) to their extant "descendant" species (like the Giant Buffalo and the Buffalo, the Giant Puma and the Puma, the Giant Beaver and the Beaver, etc.) have shown that there is no significant difference between the megafauna and the extant creatures except for size; thus implying that while the mammoth and some other creatures may have gone extinct, most of the megafauna are alive today...they're just got smaller for some reason.
I'm not too clear on this part myself, so don't harass me if I get it wrong, but I've read that there might be a correlation between the amount of CO2 in the atmosphere and the size of living beings. It's possible that there was significantly more CO2 in the atmosphere before the Ice Age, and when it hit (cold water absorbs carbon very easily) CO2 levels dropped and many animals became smaller. Again, just a possibility, but it would satisfactorily explain the disappearance of many megafaunal species.
Edited by Adminnemooseus, : Put in a couple more blank lines.

  
Minnemooseus
Member
Posts: 3941
From: Duluth, Minnesota, U.S. (West end of Lake Superior)
Joined: 11-11-2001
Member Rating: 10.0


Message 62 of 64 (417203)
08-19-2007 10:04 PM
Reply to: Message 1 by Mammuthus
10-15-2003 6:35 AM


Discover Magazine - A comet may have decimated native animals”and culture
http://discovermagazine.com/...the-great-american-extinction
What Caused the Great American Extinction? A comet may have decimated native animals”and culture. - By Jessica Ruvinsky
Excerpt from a short article:
quote:
Becker, along with two dozen-odd scientists, is studying a thin 12,900-year-old geologic layer across North America that she believes holds the legacy of a major extraterrestrial impact roughly half the size of the one that killed the dinosaurs.
"Meteor impact" strikes again!
Moose

Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.
"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." - Bruce Graham
"The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness." - John Kenneth Galbraith
"Nixon was a professional politician, and I despised everything he stood for ” but if he were running for president this year against the evil Bush-Cheney gang, I would happily vote for him." - Hunter S. Thompson
"I know a little about a lot of things, and a lot about a few things, but I'm highly ignorant about everything." - Moose

This message is a reply to:
 Message 1 by Mammuthus, posted 10-15-2003 6:35 AM Mammuthus has not replied

Replies to this message:
 Message 63 by Matt P, posted 08-24-2007 2:37 PM Minnemooseus has replied

  
Matt P
Member (Idle past 4774 days)
Posts: 106
From: Tampa FL
Joined: 03-18-2005


Message 63 of 64 (417777)
08-24-2007 2:37 PM
Reply to: Message 62 by Minnemooseus
08-19-2007 10:04 PM


Have iridium, need impact!
Hi Moose,
This is not to gripe at you, but to gripe at the Science By Press Release that these articles represent. (Here's the link to NSF:Comet May Have Exploded Over North America 13,000 Years Ago | Beta site for NSF - National Science Foundation ).
Impacts have been invoked for every mass extinction since the discovery of the K-T impact, and it's gone overboard. It's a shame, especially when some top-notch science has been done on extinction routes other than impact. For instance, the discovery of iridium at the Triassic-Jurassic boundary resulted in a paper in Science: Ascent of dinosaurs linked to an iridium anomaly at the Triassic-Jurassic boundary by Olsen et al. 2002. However, iridium does not an impact make. Other evidence for a T-J impact is lacking (http://www.lpi.usra.edu/meetings/metsoc2007/pdf/5130.pdf ), but negative evidence is harder to get published, and a lot less sexy.
To prove there was an impact, several things are needed:
http://palaeo.gly.bris.ac.uk/Palaeofiles/Triassic/bolide.htm ,
the single most important of which is an impact crater. Currently these researchers have some of the geochemical evidence, but squat as far as impacts go. There definitely should be an impact crater, given that 1) the amount of material they're invoking should leave a crater about 1/4-1/2 the size of the Yucatan impact, or 50-100 km in diameter, and 2) since it happened only 12,000 years ago, it should still be around and should be pretty dang easy to spot.
There is a bit of shoddy science being invoked- they state that a comet (made of ice) hit an ice sheet (made of ice). The inferred connotation is that ice striking ice wouldn't leave a crater. However, a body of material 10^13 kg striking the Earth at escape velocity will completely ignore whatever ice sheet is in its way, independent of its starting composition. There should be an impact!

This message is a reply to:
 Message 62 by Minnemooseus, posted 08-19-2007 10:04 PM Minnemooseus has replied

Replies to this message:
 Message 64 by Minnemooseus, posted 08-24-2007 8:56 PM Matt P has not replied

  
Minnemooseus
Member
Posts: 3941
From: Duluth, Minnesota, U.S. (West end of Lake Superior)
Joined: 11-11-2001
Member Rating: 10.0


Message 64 of 64 (417833)
08-24-2007 8:56 PM
Reply to: Message 63 by Matt P
08-24-2007 2:37 PM


Re: Have iridium, need impact!
While you certainly raise some interesting points, I think most of them do not belong in this topic, which should focus on the Pleistocene extinction event(s).
A couple of new topics probably should be started:
1) "Science by Press Release", destined for the "Is It Science?" forum.
2) "Extraterrestrial Sourced Impacts and Extinction Events", destined probably for the "Miscellaneous Topics in Creation/Evolution" forum.
Maybe someone would like to do a message 1 proposing such topics. Titles above are only my offhand suggestions.
That said, I don't find a major conflict between the Discover version and your cited NSF version of the story. Either/both are throwing out a hypothesis, and I don't think they are trying to oversell the idea. Which isn't to say that someone might try to overextend the information of those articles. But now I'm getting into a new topic time area.
Moose

This message is a reply to:
 Message 63 by Matt P, posted 08-24-2007 2:37 PM Matt P has not replied

  
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