15,000 years ago..

kkahmann said:
And the accepted therory is that these animals where hunted by modern man into extinction?
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tjsudbury said:
That's one theory

But the jury is still out on what exactly caused the extinction of what they call "Pleistocene Mega Fauna"
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"Biologists have grown super-size dragonflies that are 15 percent larger than normal by raising the insects, from start to finish, in chambers emulating Earth’s oxygen conditions 300 million years ago."

Something to do with this? I really don't know.
 
Dench said:
"Biologists have grown super-size dragonflies that are 15 percent larger than normal by raising the insects, from start to finish, in chambers emulating Earth’s oxygen conditions 300 million years ago."

Something to do with this? I really don't know.
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No.

Pleistocene Mega Fauna is the term they use for large mammals like woolly mammoths, giant sloths, woolly rhinocerous, saber tooth tigers etc that died out at the end of the last ice age.
 
tjsudbury said:
No.

Pleistocene Mega Fauna is the term they use for large mammals like woolly mammoths, giant sloths, woolly rhinocerous, saber tooth tigers etc that died out at the end of the last ice age.
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So oxygen levels do not affect them?
 
Oxygen levels 300 million years ago were much higher than today. That allowed insects, which have an inefficient method of diffusing oxygen into their blood (no lungs) to grow much larger back then than they can today.

Oxygen levels 15000 years ago were the same as today. Insects were the same size as they are today. Mammals, which have efficient lungs to extract oxygen, aren't affected the same way.
 
I still have a hard time wrapping my head around the concept of a giant sloth. I know this question doesn't apply to ANY species, but I just can't help thinking "Why?"
 
Great thread

Someone can correct me but people populated the North America only 10000 yrs ago, some of the species mentioned were extinct by then, like the lion, bear and saber cat

btw, the ROM in Toronto used to have skeletons of the short face bear, the deer, ancient moose and some more, it really puts the size of these animals into perspective standing next to them
 
I've always had a keen interest in mega fauna. One thing to note is that nearly all of the species that evolved in North America without human predators have gone extinct. The large mammals that remain such as moose and caribou evolved in Asia where human predators were present. Of course there are arguments against this and other theories, but it is interesting.
 
rhino519 said:
Great thread

Someone can correct me but people populated the North America only 10000 yrs ago, some of the species mentioned were extinct by then, like the lion, bear and saber cat

btw, the ROM in Toronto used to have skeletons of the short face bear, the deer, ancient moose and some more, it really puts the size of these animals into perspective standing next to them
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People from Asia crossed over about 10,000 years ago. Solutreans from modern day France were the first to arrive approx 15000 years ago. There is also evidence of settlement in chile at about the same time from people from the pacific islands.
Most of the evidence of early Europeans settling here is offshore due to much lower sea levels. The coast was in some places 100 kms from where it is today.
 
tjsudbury said:
That's one theory

But the jury is still out on what exactly caused the extinction of what they call "Pleistocene Mega Fauna"
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here's my theory: snow

during the ice age, the climate was dry with extensive grasslands with minimal snow cover during winter. as the climate warmed and the glaciers melter, it became wetter and snow cover increased. this would cause great stress on large grazers and in turn their predators.

note that india and africa retained their megafauna, no snow there*.

note that the animals that survived in north america; whitetail deer, blacktail, cougar, and black bear all ranged very widely, very far south, and are very adaptable in diet and habitat. and the pronghorn also ranges far south.

note another survivor, the mountain goat lives in steep country where snow doesn't really accumulate and also mountains have the advantage of aspect.

people may have pushed some animals over the brink, in rain shadow valleys, etc, but i think they where brought to near extinction/extinction by nature with a snow load they couldn't deal with.
 
Mig 25 are you a palentologist?--that theory makes the most sense of the ones I've heard.
I have read that the Clovis point is named for Clovis, New Mexico where it was first found. There were 14 of them embedded in a mammoth but that isn't what killed the mammoth.
I find this stuff fascinating.
 
kkahmann said:
Mig 25 are you a palentologist?--that theory makes the most sense of the ones I've heard.
I have read that the Clovis point is named for Clovis, New Mexico where it was first found. There were 14 of them embedded in a mammoth but that isn't what killed the mammoth.
I find this stuff fascinating.
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not a paleotologist (sp?), nor any training in the area, so am free to think.

Superbrad said:
I agree... Fascinating... And great theory mig... But why starvation vs. Migration?... Why are these critters not now roaming the deep south?
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well, in my theory, the available winter range would have been effectively an island between the snow belt and a desert ecosystem, subject to over grazing or maybe periodic grass fires or drought, wiping out the stockpiled forage.

note that deer, pronghorn, cougar, and black bear can all survive in the sonoran (and other) deserts. i doubt that large grazers could survive that environment.

note that the surviving herbavores tend to be ruminants and can survive on lower quality forage.

i don't believe for a second that a few humans with stone tools could wipe out animals that co-evolved with fierce preditors on a continental scale.
 
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