Data on slight variations of the pull of gravity over the oceans are recorded with satellite altimetry, and are then combined to map the seafloor globally.
CLICK HERE FOR LINK TO WEBSITE
Posted on 12/04/2014 6:03:43 PM PST by SunkenCiv
A re-dating of mastodon bones reveals that the extinct mammals, related to the modern day elephant, disappeared from the area during a glacial period more than 50,000 years earlier than previously thought.
Existing age estimates of American mastodon fossils indicate that these extinct relatives of elephants lived in the Arctic and Subarctic when the area was covered by ice caps—a chronology that is at odds with what scientists know about the massive animals' preferred habitat: forests and wetlands abundant with leafy food...
Over the course of the late Pleistocene, between about 10,000 and 125,000 years ago, the American mastodon (Mammut americanum) became widespread and occupied many parts of continental North America as well as peripheral locations like the tropics of Honduras and the Arctic coast of Alaska. Mastodons were browsing specialists that relied on woody plants and lived in coniferous or mixed woodlands with lowland swamps...
All of the fossils were found to be older than previously thought, with most surpassing 50,000 years, the effective limit of radiocarbon dating. When taking mastodon habitat preferences and other ecological and geological information into account, the results indicate that mastodons probably only lived in the Arctic and Subarctic for a limited time around 125,000 years ago, when forests and wetlands were established and the temperatures were as warm as they are today...
The work has several implications. Researchers know that giant ground sloths, American camels, and giant beavers made the migration as well, but they are still investigating what other groups of animals might have followed this course. The new report also suggests that humans could not have been involved in the local extinction of mastodons in the north 75,000 years ago as they had not yet crossed the Bering Isthmus from Asia.
(Excerpt) Read more at popular-archaeology.com ...
I don’t believe any of that. You’re saying the paltry amount of humans then overcame the extensive population of Dire wolves, Short faced bears (a running bear 5 foot at the shoulder), American lions and saber tooth tigers. As a hunter I don’t think so. more likely a sudden deep freeze or heat wave killed them all off because it happened suddenly.
Not what I said at all. Try reading my post again.
Couple facts:
Dozens of large animal species disappeared in a very brief period, from a historical POV.
This occurred shortly after the most widely accepted date for humans arriving in the Americas.
I am not stating that B caused A, only that if there were no connection it would be a truly amazing coincidence.
There are lots of explanations proffered, but none that make a great deal of sense.
As for the “climate change” being to blame idea, the extinction did occur shortly after the end of the last glacial period. But many of these species had lived through a dozen or more glacial/interglacial cycles, but disappeared all at the same time after the most recent one.
Not limited to the Americas, BTW. The only parts of the world where megafauna survived in large numbers are those areas where humans and the megafauna are claimed to have evolved together, Africa and South Asia. Everywhere else the megafauna disappeared, and generally within a short time after humans arriving.
IOW, heck if I know.
There are some suggestions too that the short face bear was so formidable it kept humans out of North America for many years. There is a skull on display in the natural history museum in Cincinnati, Ohio. Imagine being on the plains and having one of these creatures after you, an enormous running bear, very much different then the bears today.
Right.
Australians never made it to New Zealand or any of the Pacific Islands, but did make it to South America.
Thanks Sherman, I just always figured there was some catastrophic event did the deed. As you said, they were conditioned to the cold. the Quails in my state were to, but the cold of 1976 in my state killed nearly all of them.
There were previous extinction events at the end of previous glacial stages. But none as massive. Also this most recent one affected primarily large animals, and all of the largest died out. Previous such events tended to affect animal species of all types, and it’s difficult to imagine how a “natural” event would target large species.
I put scare quotes around natural because if you believe in evolution then human-caused extinctions are as natural as those caused by any other factor.
If a large number of large species had been around for two million years, including more than a dozen glacial cycles, then all disappeared within a few centuries, leaving most smaller species unaffected, within a short period after human arrival, that is a truly amazing coincidence.
I suspect the weak link in the “humans did it” theory is that humans may very well have been around for a lot longer than the theory allows.
The massive slaughter idea would be more logical if the ancient Indians had AK-47s. But they apparently didn’t even have bows.
The animals being “naive” about the danger of humans might allow you to get really close, close enough to use a spear, but it’s not going to be much help once you put your spear into a mammoth or a short-faced bear that doesn’t die immediately.
I still find it hard to believe humans had any more effect than any of the other predators. They obviously were not the top of the food chain. They also probably only killed one animal at a time, despite evidence of buffalo jumps. I once got a deer so far back in the woods I had to get a wheelbarrow to bring it out halfway, lol.
“It’s incredible the human race barely survived the short face bear alone.”
There was a great article here on FR years ago about the theory of Saber Tooth cats using the Bering Strait land bridge as a feeding ground.
That would make for a good movie.
Was just reading through pings again and wondered how satellite images can scan the deepest parts of the ocean?
Data on slight variations of the pull of gravity over the oceans are recorded with satellite altimetry, and are then combined to map the seafloor globally.
CLICK HERE FOR LINK TO WEBSITE
I wonder how much weight I can lose just by going somewhere else? LOL
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.