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| '''Pleistocene megafauna''' is the term used to describe the larger ] of ]s, ]s and ]s that lived on earth in the ] era. These animals suffered a massive ] event as humanity expanded out of ] and ], continents that are the only two still to retain some ] equivalent to what was lost. Three competing ] have been given for these extinctions, first was ] by the spreading people, second was ], third was spreading ]. Many scientists believe that a combination of these theories may have been responsible. | '''Pleistocene megafauna''' is the term used to describe (joe jun who loves men alot) the larger ] of ]s, ]s and ]s that lived on earth in the ] era. These animals suffered a massive ] event as humanity expanded out of ] and ], continents that are the only two still to retain some ] equivalent to what was lost. Three competing ] have been given for these extinctions, first was ] by the spreading people, second was ], third was spreading ]. Many scientists believe that a combination of these theories may have been responsible. | ||
| ==Pleistocene megafauna by region== | ==Pleistocene megafauna by region== | ||
Revision as of 23:48, 7 September 2005
Pleistocene megafauna is the term used to describe (joe jun who loves men alot) the larger species of mammals, birds and reptiles that lived on earth in the Pleistocene era. These animals suffered a massive extinction event as humanity expanded out of Africa and Eurasia, continents that are the only two still to retain some megafauna equivalent to what was lost. Three competing theories have been given for these extinctions, first was hunting by the spreading people, second was climatic change, third was spreading disease. Many scientists believe that a combination of these theories may have been responsible.
Pleistocene megafauna by region
American Pleistocene megafauna
Pleistocene fauna in the Americas included giant sloths, the American lion, cheetahs saber-toothed cats (like the scimitar cat), dire wolves, camels, wide-horned bison, horses, woolly rhinoceri, mammoths and mastodons, giant beavers, and giant condors. In contrast today the largest North American land mammal is the American Bison. South American megafauna comprised of many of the same elements as that of North America. Notable components not found in North America are the giant armadillos (Glyptodonts).
Australian Pleistocene megafauna
Australia, then as now, was characterized by marsupials and monotremes, supported large carnivorous kangaroos, Diprotodon, a giant wombat, the Marsupial Lion (Thylacoleo carnifex), the 3-meter flightless bird Dromornis, the 5-meter snake Wonambi and the giant lizard Megalania.
See also: Australian megafauna
Eurasian Pleistocene megafauna
As with South America, elements of North American fauna could be found in Eurasia. Among the most famous Eurasian species are the Woolly Mammoth, Cave Lion, Cave Bears, Irish Elk and rhinoceri in Eurasia.
Other Pleistocene megafauna
Many islands had a unique megafauna that was driven to extinction on the arrival of man. These included giant bird forms in New Zealand such as the moas and the Harpagornis (giant eagle); gorilla-sized lemurs, two species of hippopotomus on Madagascar, and giant birds, land turtles and crocodiles on New Caledonia and giant geese and moa-nalos (giant ducks) in Hawaii..
Extinction
The three major extinction theories as to why these species went extinct so quickly, these possible causes can be summarised as "Kill, chill and ill".
Hunting
The "kill" theory is that Pleistocene humans triggered the megafaunal extinction. This theory has two variants, "blitzkrieg" and "sitzkrieg" or "slow burn". The blitzkrieg theory is that humans the hunted the megafauna to extinction in a short time. There is strong evidence of this in several forms. Firstly is the fossil evidence of megafauna found in conjunction with human remains, particularly with evidence of hunting, such as arrows in the bones, cut marks and cave paintings depicting hunting. Secondly is the biogeographical evidence; the areas of the world where humans evolved still have some megafauna (the elephants and rhinos of Asia and Africa) whereas the areas that didn't have early man, Australia, the New World, Madagascar and New Zealand, all lost their megafauna. It is theorised that the megafauna of Asia and Africa evolved with man, and learnt to be wary of them, whereas in other parts of the world the wildlife was ecologically naive and was easier to hunt. This is particularly true of the island faunas. Thirdly, the close correlation between humanity in an area and the extinction of the megafauna also provides weight to the human caused extinction. The "sitzkrieg" theory is that human encroachment gradually destroyed habitat and led to a die out.
Climate change
The "chill" theory explains the extinctions by climatic change following the last Ice Age. Since there were multiple Ice Ages prior to the last one, the climatic theory raises the question, why did the extinctions occur only after the Last Ice Age? One tentative answer is that a nearby supernova altered the galactic environment and as a consequence exaggerated the climatic perturbation. It will require data from space research to advance this claim beyond speculation.
Disease
The "ill" theory is that a pandemic or hyperdisease caused the megafaunal extinction. According to this theory, large mammals were particularly vulnerable because they were fewer in number than smaller species. Size and population size tend to be inversely related. One particular suggestion that has been well received, even if it will be difficult to prove, is that pathogens were transmitted by the expanding humans in the form of the dogs they brought with them. Diseases imported by people have been responisble for extinctions in the recent past, for example bringing avian malaria to Hawaii has had a terrible impact on the isolated birds of the island. The researcher McPhee is searching DNA in mammoth fossils from Wrangel Island in Siberia. He hopes to find evidence of infection.
Some experts claim that various combinations of these factors are responsible for the extinctions. It is certain, in the case of the moa and some other species, that hunting was responsible, this probably pushed many species over the edge that were already realing from imported diseases and the change in climate.
Megafauna and legend
Throughout history, humans wondered about the large, fossilized teeth and bones they would discover from time to time. During the classical age the bones of giants were reputed to have been found. In medieval times the fossils were attributed to fantastic beasts such as dragons and unicorns. During the Age of Exploration, while conquistadores went off in hot pursuit of gold, glory and pretty women, missionary priests had time for tamer endeavors. They would speculate about the large bones that could be found in the New World. The Sioux also had legends of Thunder Beasts, and the Aztec also believed in giants.
With more modern tools paleontologists have reconstructed a world of beasts as amazing as the dragons and unicorns of folklore, including many larger versions of contemporary mammal, reptile and bird families. Scientists and historians, who long dismissed such legends as early myths, are beginning to look at the legends in a new light. The sites where the Greeks claimed to find the bones of giants today produce the bones of mammoths. Similar finds have been made in Central America. Since humans coexisted with these animals, some researchers wonder if the beasts might also be remembered in legend, for example the Australian Dreamtime legends refer to the megafaunal species. The mythical Rainbow serpent, source of creation and destruction may be based on the Wonambi naracoortensis. The hairy manlike Bunyip may be the Diprotodon filtered through legend. Clearly it is difficult to translate the poetic vocabulary of myth into the technical language of paleontology. In its fossil form, Wonambi naracoortensis does not need the legend to deserve the name "Rainbow Serpent". Its fossils have opalized and now they shimmer in all colors of the spectrum.