Megafauna
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Megafauna are generally defined as animals that weigh over 500 kg to 1 tonne, i.e., any animal larger than the largest widespread domestic animal, the domestic bull. Some authors use much lower thresholds, even as low as 50 kg (making humans a megafauna species), but they are not widely accepted. The term is also used to refer to particular groups of large animals, both to extant species and, more often, those that have become extinct in geologically recent times.
Megafauna animals are generally K-strategists, with great longevity, slow population growth rates, low death rates, and few or no natural predators capable of killing adults. These characteristics make megafauna highly vulnerable to human exploitation. Many species of megafauna have become extinct within the last million years, and, although some biologists dispute it, human hunting is often cited as the cause.
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[edit] Usage
The tense in which the term is used is usually apparent from the context:
- A particular group of large, extinct animals. For example, American megafauna, meaning "the various species of large American mammal that became extinct about 13,000 years ago".
- Any group of large animals. For example, South American megafauna, meaning "all large animals in South America today".
[edit] Extinction
Two major hypotheses have been proposed to explain the extinction of megafauna. The first cites human intervention, noting that the time of human appearances on the various continents was the time that they became extinct. However, this is not widely accepted because megafauna actually began to decline before humans arrived in some places (North America) and did not decline due to human predation (France) in others. There is also a distinct lack of massive kill sites in the archaeological record.[citation needed]
The second is that climate changes, most notably increases in average temperature, caused them to die. While the woolly mammoth survived on at least two islands in the region of the Bering Strait for thousands of years after the end of the last glaciation 12,000 years ago, this indicates that it was not just a change in climate and accompanying vegetation that killed off megafauna in other regions, but that the replacement of other species more optimally adapted for the conditions that came with the end of the Pleistocene caused significant population duress.
New evidence suggests that humans were the ultimate cause of the extinction of megafauna in Australia. The evidence indicates the arid regional climate at the time of extinction was similar to arid regional climate of today, and that the megafauna were strongly adapted to an arid climate. These pieces of evidence rule out climate change as a cause of extinction. The evidence indicates that all forms of megafauna became extinct in the same rapid timeframe — approximately 47,000 years ago — this being the time at which humans entered the landscape. The evidence indicates the main mechanism for extinction was human burning of a then much less fire-adapted landscape. Isotopes from the teeth indicate such burning caused sudden drastic changes in vegetation and sudden drastic changes in the diet of surviving species, as well as the loss of megafaunal species [1] [2] [3].
[edit] Megafauna by continent
"†" denotes extinct megafauna
[edit] African megafauna
- African Buffalo (Syncerus caffer)
- African Bush Elephant (Loxodonta africana)
- African Forest Elephant (Loxodonta cyclotis)
- Ancylotherium † (Ancylotherium hennigi)
- Arsinoitherium † (Arsinoitherium zitteli)
- Black Rhinoceros (Diceros bicornis)
- Bongo (Tragelaphus eurycerus)
- African Deinotherium † (Deinotherium bozasi)
- African Dinofelis † (Dinofelis barlowi)
- Common Eland (Taurotragus oryx)
- Giant Eland (Taurotragus derbianus)
- Giant Long-horned Buffalo † (Bubalus antiquus)
- Giraffe (Giraffa camelopardalis)
- Greater Kudu (Tragelaphus strepsiceros)
- Western Gorilla (Gorilla gorilla)
- Eastern Gorilla (Gorilla beringei)
- Hartebeest (Alcelaphus buselaphus)
- African Hippopotamus (Hippopotamus amphibius)
- Lion (Panthera leo)
- Nile Crocodile (Crocodylus niloticus)
- Okapi (Okapia johnstoni)
- Quagga † (Equus quagga quagga)
- Sable Antelope (Hippotragus niger)
- Saltwater Crocodile (Crocodylus porosus)
- East African Oryx (Oryx beisa)
- Waterbuck (Kobus ellipsiprymnus)
- White Rhinoceros (Ceratotherium simum)
- Black Wildebeest (Connochaetes gnou)
- Blue Wildebeest (Connochaetes taurinus)
- Imperial Zebra (Equus grevyi)
- Plains Zebra (Equus quagga)
- Cape Mountain Zebra (Equus zebra)
- Mountain Zebra (Equus hartmannae)
- Giant Forest Hog (Hylochoerus meinertzhageni)
- Nyala (Tragelaphus angasii)
- Mountain Nyala (Tragelaphus buxtoni)
- Gemsbok (Oryx gazella)
- African Wild Ass (Equus africanus)
- African Manatee (Trichechus africanus)
[edit] Australian megafauna
- Diprotodonts †
- Genyornis † (Genyorns newtoni)
- Megalania prisca †
- Marsupial Lion †
- Palorchestes †
- Procoptodon †
- Saltwater Crocodile
See also: Australian megafauna
[edit] Eurasian megafauna
- Mountain Anoa (Bubalus quarlesi)
- Lowland Anoa (Bubalus depressicornis)
- Asian Elephant (Elephas maximus)
- Asian Lion (Panthera leo persica)
- Aurochs † (Bos primigenius)
- Bactrian Camel (Camelus bactrianus)
- Banteng (Bos javanicus)
- Cave Bear † (Ursus spelaeus)
- Cave Lion † (Panthera leo spelaea)
- Chalicotherium †
- European Jaguar † (Panthera gombaszoegensis)
- Gastornis †
- Gaur (Bos gaurus)
- Gavial (Gavialis gangeticus)
- Giant Unicorn † (Elasmotherium sibiricum)
- Gigantopithecus † (Gigantopithecus blacki)
- Heck horse (Equus caballus)
- Heck cattle (Bos taurus)
- Hyaenodon † (Hyaenodon horridus)
- Indricotherium † (Indricotherium transouralicum)
- Indian Rhinoceros (Rhinoceros unicornis)
- Giant Irish Elk † (Megaloceros giganteus)
- Javan Rhinoceros (Rhinoceros sondaicus)
- Kaluga
- Kouprey (Bos sauveli)
- Steppe Mammoth † (Mammuthus trongotherii)
- Giant Mammoth † (Mammuthus meridionalis)
- Mekong giant catfish
- Moose (Alces alces)
- Nilgai (Boselaphus tragocamelus)
- Przewalski's Horse - Takhi (Equus ferus przewalski)
- Saltwater Crocodile (Crocodylus porosus)
- Stegodon †
- Steppe Wisent † (Bison priscus)
- Sturgeon
- Sumatran Rhinoceros (Dicerorhinus sumatrensis)
- Syrian Camel †
- Tamaraw (Bubalus mindorensis)
- Bengal Tiger (Panthera tigris tigris)
- Siberian Tiger (Panthera tigris altaica)
- Wisent (Bison bonasus)
- Water Buffalo (Bubalus bubalis)
- Woolly Rhinoceros † (Coelodonta antiquitatis)
- Yak (Bos grunniens)
- Wild Boar (Sus scrofa)
- Dromedary Camel (Camelus dromedarius)
- Red Deer (Cervus elaphus)
- White Lipped Deer (Cervus albirostris)
- Sambar Deer (Cervus unicolor)
- Pere David's Deer (Elaphurus davidianus)
- Takin (Budorcas taxicolor)
- Brown Bear (Ursus arctos)
- Onager (Equus hemionus)
- Kiang (Equus kiang)
- Malayan Tapir (Tapirus indicus)
- Dugong (Dugon dugon)
[edit] North American megafauna
- Alaskan Moose (Alces alces gigas)
- American Lion † (Panthera leo atrox)
- American Bison (Bison bison)
- Ancient Bison † (Bison antiquus)
- Columbian Mammoth † (Mammuthus columbi)
- Pygmy Mammoth † (Mammuthus exilis)
- Woolly Mammoth † (Mammuthus primigenius)
- American Alligator (Alligator mississippiensis)
- American Crocodile (Crocodylus acutus)
- American Scimitar Cat † (Homotherium serum)
- Aepycamelus † (Aepycamelus giraffinus)
- Camelops † (Camelops hesternus)
- Caribou (Rangifer tarandus)
- Cuvieronius † (Cuvieronius tropicus)
- American Horse † (Equus scotti)
- Yukon Wild Ass † (Equus asinus lambei)
- Northern Glyptodon † (Glyptodon texanum)
- Grizzly Bear (Ursus arctos horribilis)
- Harlan's Ground Sloth (Paramylodon harlani)
- Jefferson's Ground Sloth (Megalonyx jeffersoni)
- Laurillard's Ground Sloth (Eremotherium laurillardi)
- Shasta Ground Sloth (Nothrotheriops shastensis)
- Longhorn Bison † (Bison latifrons)
- American Mastodon † (Mammut americanum)
- Giant Ground Sloth † (Megatherium americanum)
- Polar Bear (Ursus maritimus)
- Sabertooth Cat † (Smilodon populator)
- Short-faced Bear † (Arctodus simus)
- Wapiti Elk (Cervus canadensis)
- American Black Bear (Ursus americanus)
- Musk Ox (Ovibos moschatus)
[edit] Central & South American megafauna
- Green Anaconda (Eunectes murinus)
- Black Caiman (Melanosuchus niger)
- Cuvieronius † (Cuvieronius hyodon)
- Doedicurus † (Doedicurus clavicaudatus)
- Galapagos Tortoise (Geochelone nigra)
- Southern Glyptodon † (Glyptodon asper)
- Litoptern † (Macrauchenia patachonica)
- Giant Ground Sloth † (Megatherium americanum)
- Orinoco Crocodile (Crocodylus intermedius)
- Palaeolama mirifica † (an extinct Llama)
- Tapirus veroensis † (an extinct Tapir)
- Tapirus bairdii (Baird's Tapir)
- Tapirus pinchaque (Woolly Tapir)
- Tapirus terrestris (Brazilian Tapir)
- Terror bird † (Phorushacos Longisimmus)
- Trichechus inunguis (Amazonian Manatee)
- Trichechus manatus (Caribbean Manatee)
- Toxodons † (Toxodon platensis)
[edit] Island megafauna
[edit] Ocean megafauna
- Baleen whales (15 known species)
- Basking Shark
- Beaked whales (21 known species)
- Beluga
- Bluefin Tuna (3 known species)
- Colossal Squid
- Dugong
- Elephant Seal
- Giant clam
- Giant grouper
- Giant sea bass
- Giant squid
- Goliath grouper
- Great White Shark
- Green Sea Turtle
- Greenland Shark
- Leopard Seal
- Leatherback Turtle
- Manatees (3 known species)
- Manta Ray
- Three species of marlin
- Megalodon †
- Megamouth Shark
- Narwhal
- Oarfish
- Ocean Sunfish
- Seven species of oceanic dolphin
- Opah
- Pacific sleeper shark
- Porbeagle
- The six non-dwarf species of Sawfish
- Sperm Whales (3 known species)
- Steller's Sea Cow †
- Steller's Sea Lion
- Thresher Shark
- Tiger Shark
- Six species of Sturgeon
- Walrus
- Whale Shark
[edit] Arctic megafauna
- Caribou
- Elephant Seal
- Glyptodon †
- Ice Age Camel †
- Irish Elk †
- Mammoth †
- Musk Ox
- Polar Bear
- Smilodon †
- Walrus
[edit] Domestic megafauna
[edit] See also
- Bergmann's Rule
- Cope's rule
- Deep-sea gigantism
- Fauna
- Island gigantism
- List of megafauna recently discovered
- Pleistocene megafauna