Diprotodon Megafauna : Wiki Commons
Posted on 07/13/2012 7:38:52 PM PDT by SunkenCiv
As sabre tooth tigers and woolly mammoths were wandering around Europe, unique, giant prehistoric animals were living in Australia -- three metre tall kangaroos and wombat-like creatures, the size of a four-wheel drive, were just some of the curious creatures Down Under. Yet mysteriously, sometime during the last 100,000 years, they disappeared forever.
The extinction of these giant animals, known as megafauna, has generated great debate. One group advocates "human blitzkrieg" -- those asserting the first Australians hunted these beasts to extinction. Others, myself included, find there is too little evidence to confidently attribute responsibility to any particular factor. Nonetheless, climatic instability during the last ice age cannot be discounted.
Adding to the difficulty in settling the debate is the lack of fossil records -- one of the characteristics of the dry Australian continent. However, there is just one place in Australia where the fossils of megafauna are found alongside concurrent evidence of human activity: Cuddie Springs, an ancient lake near Brewarrina in north-western New South Wales. A giant flightless bird called Genyornis, the giant wombat-like Diprotodon, Komodo-sized goannas and three metre tall kangaroos are just a few of the animals identified here.
(Excerpt) Read more at heritagedaily.com ...
Diprotodon Megafauna : Wiki Commons
Abstract: More than 85 percent of Australian terrestrial genera with a body mass exceeding 44 kilograms became extinct in the Late Pleistocene. Although most were marsupials, the list includes the large, flightless mihirung Genyornis newtoni. More than 700 dates on Genyornis eggshells from three different climate regions document the continuous presence of Genyornis from more than 100,000 years ago until their sudden disappearance 50,000 years ago, about the same time that humans arrived in Australia. Simultaneous extinction of Genyornis at all sites during an interval of modest climate change implies that human impact, not climate, was responsible. [1/8/99 Pleistocene Extinction of Genyornis newtoni: Human Impact on Australian Megafauna (Gifford H. Miller, John W. Magee, Beverly J. Johnson, Marilyn L. Fogel, Nigel A. Spooner, Malcolm T. McCulloch, Linda K. Ayliffe, Science, Volume 283, Number 5399 Issue of 8 Jan 1999, pp. 205 -- 208 )]In Horus, a journal published by the late David Griffard, vol II no 1 (1985), Barry Fell was interviewed. Alas, DG went down in a private plane after the seventh issue. Among other things:
In the middle of Australia there is a group of three or four meteorite craters called the Henley craters. They're like the Arizona meteorite crater -- not so big, but there are several of them -- and, like in Arizona, the land was scattered with pieces of iron meteorite. I think the [inaudible] dating very slow growing desert plants. They believe that the date is about 5000 years ago -- the formation of the craters. The Aboriginal name for this area is the "Place Where The Sun Walked on the Earth" -- they must have seen it!
Perhaps it was due to the eruption of Toba.
/johnny
If the humans at that time had gattline guns and AK 47’s maybe they could have made a dent in the wildlife population but only someone entirely stupid would say humans with spears caused their extintion...Its amazing how stupid some people are...
Yes, it's amazing.
By the way: What's a "gattline gun?"
Regards,
THAT is a very good point!
No mystery. The Great flood killed them all. Read the book of Genesis!
Rupp at the University of Chicago had a study done during the Dino Killer contravertisity. They found that something kills off a whole lot of things about every 20 million years with a bunch of not so major killings scatted in between, I will look for a reference.
Perhaps it was due to the eruption of Toba.
—
Toba errupts 72,000 years ago. Megafauna extinct 50,000 years ago. One not connected to the other directly by 22,000 years. Toba might have more to do with the migtation of the Aborigines (from where ever they originated) to Austrailia.
something kills off a whole lot of things about every 20 million years
—
Notice that the common thread in those exinction events is large animal demise? This might indicate that there is some sort of peridic gravity change. A large dinosaur whole, living, and intact today would be crushed by its own weight - their bones are neither large enough nor dense enough to support their weight.
There was some article published years ago on local gravity fuctuations indicting that gravity is growing weaker in certain regions of the Earth. I don’t remember more than that.
Really, that is a stretch. It’s pretty simple actually. Large animals need a lot of food. If there is a large meteor strike, it blots out sunshine, plants die, herbivores die, and large carniores die.
The othe simple explanation is a blight caused by drought or a virus.
No mystery, you don’t know what you’re talking about.
Here is a Wili artical, I spelled Raup wrong, I haven’t read the book in 10 years. It follows the PDF and is a LOT clearer.
http://en.wikipedia.org/wiki/Extinction_event
If humans considered the last remaining ones a threat (or were hungry as hell) they might be able to finish off the last of a species, and that may have happened — but I agree with ya, Australia, like the Americas, was devoid of a small band of super-hunters that swept the continents clean of megafauna.
Thanks Little Bill.
The paleontological strata show waves of mass extinction, some global. Massive taxa-wide dieoffs had been identified even among gradualists by 1950, and more than a century earlier data purportedly supporting Biblical catastrophism included a bed of fossil skeletons of billions of fish which clearly died in agony. And obviously they didn’t drown (as I said, purportedly). Raup:
[snip] In 1984, paleontologists David Raup and Jack Sepkoski published a paper claiming that they had identified a statistical periodicity in extinction rates over the last 250 million years using various forms of time series analysis. [/snip]
http://en.wikipedia.org/wiki/Nemesis_(hypothetical_star)#Claimed_periodicity_of_mass_extinctions
http://www.pnas.org/cgi/reprint/81/3/801.pdf
IMPLICATIONS
If periodicity of extinctions in the geologic past can be demonstrated, the implications are broad and fundamental. A first question is whether we are seeing the effects of a purely biological phenomenon or whether periodic extinction results from recurrent events or cycles in the physical environment.If the forcing agent is in the physical environment, does this reflect an earthbound process or something in space?
If the later, are the extraterrestrial influences solar, solar system, or galactic? Although none of these alternatives can be ruled out now, we favor extraterrestrial causes for the reason that purely biological or earthbound physical cycles seem incredible, where the cycles are of fixed length and measured on a time scale of tens of millions of years. By contrast, astronomical and astrophysical cycles of this order are plausible even though candidates for the particular cycle observed in the extinction data are few. One possibility is the passage of our solar system through the spiral arms of the Milky Way Galaxy, which has been estimated to occur on the order of 108 years (21). Shoemaker has argued (21) that passage through galactic arms should increase the comet flux and this could, following the Alvarez hypothesis (2), provide an explanation for the biological extinctions. Two of the extinction events being considered here (Late Cretaceous and Late Eocene) are associated with evidence for meteorite impact (23,24). However, much more information is needed before definitive statements about causes can be made. It may turnout that the biological extinction record is sensitive to periodic phenomena that other indicators have failed to recognize.
The implications of periodicity for evolutionary biology are profound. The most obvious is that the evolutionary system is not "alone"in the sense that it is partially dependent upon external influences more profound than the local and regional environmental changes normally considered. Much has been written about the "bottlenecking" effect of mass extinction. With kill rates for species estimated to have been as high as 77% and 96% for the largest extinctions (11,25), the biosphere is forced through narrow bottlenecks and the recovery from these events is usually accompanied by fundamental changes in biotic composition (26). Without these perturbations, the general course of macroevolution could have been very different.
Structures on Earth under the current gravity can only be so large using known materials. When a structure's mass exceeds the strength of the building material, the structure collapses. Which is why we cannot build structures miles high. On the Moon with its lighter gravity, building such structures would be possible.
The largest animal structures on Earth are found in the oceans as water's buoyancy provides the needed cushion against the pull of gravity. A large dinosaur simply has too much mass for the bone destiny to support on Earth in this geological period. Their structures are simply too flimsy.
Then there are the hydralic problems: how does the blood get pumped that high (30 feer or more) under reasonable preasure so as not to explode the heart?
Where do you put these structures? Large Dinos vs. Human
For the smaller land dwelling Brachiosaurus: 85 feet, 55,100 to 96,800 lbs and up from there for the really big ones.
Blue Whale vs. Human
For the water dwelling Bule Whale: 98 feet. 400,000 lbs plus
More here on the problems with dinosaurs and better explainions:
The Paradox of Large Dinosaurs
Sorry about the large graphics, but I could not dind smaller ones.
roughly 15-20 major and minor extinctions in earth’s history. The big one we currently know the most about is the Permian-Triassic extinction. 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects.
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.
