Megafauna: Wikis

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Loxodonta africana, Earth's largest living land animal

In terrestrial zoology, megafauna (Ancient Greek megas "large" + New Latin fauna "animal") are "giant", "very large" or "large" animals. Their original and most common definition is 100 lb, often rounded in the metric system to 40 or 45 kg.[1][2] This thus includes many species not popularly thought of as overly large, such as white-tailed deer and red kangaroo.

In practice the most common usage encountered in academic and popular writing describes land animals roughly larger than a human which are not (solely) domesticated. The term is especially associated with the Pleistocene megafauna — the giant and very large land animals considered archetypical of the last ice age such as mammoths.[3] It is also commonly used for the largest extant wild land animals, especially elephants, giraffes, hippopotamuses, rhinoceroses, moose, condors, etc.

Other common uses are for giant aquatic species, especially whales, any larger wild or domesticated land animals such as larger antelope and cattle, and dinosaurs and other extinct giant reptilians.

The term is also sometimes applied to animals (usually extinct) of great size relative to a more common or surviving type of the animal, for example the 1 m (3.28 ft) dragonflies of the Carboniferous age.

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Ecological strategy of megafauna

Megafauna — in the sense of the largest mammals and birds — 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, although not exclusive to such megafauna, make them highly vulnerable to human over-exploitation.

Megafaunal mass extinctions

A well-known mass extinction of megafauna, the Pleistocene–Holocene extinction event, occurred at the end of the last ice age glacial period, and wiped out many giant ice age animals, such as woolly mammoths, in the Americas and northern Eurasia. However, this extinction pulse near the end of the Pleistocene was just one of a series of megafaunal extinction pulses that have occurred during the last 50,000 years over much of the Earth's surface, with Africa and southern Asia being largely spared. Outside of Eurasia, these megafaunal extinctions followed a distinctive landmass-by-landmass pattern that closely parallels the spread of humans into previously uninhabited regions of the world, and which shows no correlation with climate.[4][5] Australia was struck first around 50,000 years ago, followed by the Solomon Islands 30,000 years ago, the Americas 13,000 years ago, Cyprus 9000 years ago, the Antilles 6000 years ago, New Caledonia 3000 years ago, Madagascar 2000 years ago, New Zealand 800 years ago, the Mascarenes 400 years ago, and the Commander Islands 250 years ago. Actually, nearly all of the world's isolated islands could furnish examples of extinctions occurring shortly after the arrival of Homo sapiens. (Most of these islands, such as the Hawaiian Islands, never had terrestrial megafauna, so their extinct fauna were smaller.)

Continuing human hunting and environmental disturbance has led to additional megafaunal extinctions in the recent past, and has created a serious danger of further extinctions in the near future (see examples below).

A number of other mass extinctions occurred earlier in Earth's geologic history, in which some or all of the megafauna of the time also died out. Famously, in the Cretaceous–Tertiary extinction event the dinosaurs and most other giant reptilians were eliminated. However, the earlier mass extinctions were more global and not so selective for megafauna; i.e., many species of other types, including plants, marine invertebrates and plankton, went extinct along with the dinosaurs. Thus, the earlier events must have been caused by more generalized types of disturbances to the biosphere.

Examples of megafauna

The following are some notable examples of animals often considered as megafauna (in the sense of the "large animal" definition). This list is not intended to be exhaustive:

Gallery

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Extinct megafauna

Living megafauna

See also

References

  1. ^ Defense of the Earth. Past consequences of climate change: Evolutionary history of the mammals.
  2. ^ Corlett, R. T. (2006). Megafaunal extinctions in tropical Asia. Tropinet 17 (3): 1–3.
  3. ^ Ice Age Animals. Illinois State Museum
  4. ^ Martin, P. S. (2005). "Chapter 6, Deadly Syncopation". Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America. University of California Press. pp. 118-128. ISBN 0520231414. http://books.google.com/books?id=eThoCsL1hRAC.  
  5. ^ Burney, D. A.; Flannery, T. F. (July 2005). "Fifty millennia of catastrophic extinctions after human contact". Trends in Ecology & Evolution (Elsevier) 20 (7): 395-401. doi:10.1016/j.tree.2005.04.022. http://www.anthropology.hawaii.edu/Field%20Schools/Kauai/Publications/Publication%204.pdf. Retrieved 2009-06-12.  

Simple English

The term megafauna (Ancient Greek megas "large" + New Latin fauna "animal") has two distinct meanings in the biological sciences. The less commonly found meaning is of any animal which can be seen with the unaided eye, in contrast to microfauna. The more commonly found meaning, discussed in this article, is of "giant", "very large" or "large" animals — although there is no standard definition of a minimum size.


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