Related topics: climate change , dinosaurs , conservation
Extinction
hideIn biology and ecology, extinction is the end of a species or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point). Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "re-appears" (typically in the fossil record) after a period of apparent absence.
Through evolution, new species arise through the process of speciation—where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche—and species become extinct when they are no longer able to survive in changing conditions or against superior competition. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Extinction, though, is usually a natural phenomenon; it is estimated that 99.9% of all species that have ever lived are now extinct.
Prior to the dispersion of humans across the earth, extinction generally occurred at a continuous low rate, mass extinctions being relatively rare events. Starting approximately 100,000 years ago, and coinciding with an increase in the numbers and range of humans, species extinctions have increased to a rate unprecedented since the Cretaceous–Tertiary extinction event. This is known as the Holocene extinction event and is at least the sixth such extinction event. Some experts have estimated that up to half of presently existing species may become extinct by 2100.
For more information about Extinction, read the full article at
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News tagged with extinction
Superior Super Earths
Space & Earth / Space Exploration
Nov 30, 2009 |
4.6 / 5 (55) |
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Super Earths are named for their size, but these planets - which range from about 2 to 10 Earth masses - could be superior to the Earth when it comes to sustaining life. They could also provide an answer to ...
Antarctica served as climatic refuge in Earth's greatest extinction event
Space & Earth / Earth Sciences
Dec 02, 2009 |
4.6 / 5 (10) |
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A new fossil species suggests that some land animals may have survived the end-Permian extinction by living in cooler climates in Antarctica. Researchers have identified a distant relative of mammals that apparently survived ...
Blue whales singing with deeper voices
Dec 08, 2009 |
4.3 / 5 (7) |
8
(PhysOrg.com) -- Blue whales, the largest animals on earth, are singing with deeper voices every year, but scientists are unsure of the reason.
Study shows loss of 15-42 percent of mammals in North America
Dec 17, 2009 |
3.2 / 5 (9) |
5
If the planet is headed for another mass extinction like the previous five, each of which wiped out more than 75 percent of all species on the planet, then North American mammals are one-fifth to one-half the way there, according ...
Sucker-footed bats don't use suction after all (w/ Video)
Dec 14, 2009 |
4.3 / 5 (3) |
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There are approximately 1,200 species of bats worldwide. Of that total, only six are known to roost with their heads pointed upward. Investigators did not know why, because they knew next to nothing about ...
Late-surviving megafauna exposed by ancient DNA in frozen soil
Dec 15, 2009 |
4.5 / 5 (2) |
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Extinct woolly mammoths and ancient American horses may have been grazing the North American steppe for several thousand years longer than previously thought. After plucking ancient DNA from frozen soil in ...
Researchers reveal ancient origins of modern opossum
Other Sciences / Archaeology & Fossils
Dec 16, 2009 |
4 / 5 (2) |
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A University of Florida researcher has co-authored a study tracing the evolution of the modern opossum back to the extinction of the dinosaurs and finding evidence to support North America as the center of ...
Killer fungus threatening amphibians
Nov 23, 2009 |
5 / 5 (1) |
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Amphibians like frogs and toads have existed for 360 million years and survived when the dinosaurs didn't, but a new aquatic fungus is threatening to make many of them extinct, according to an article in the ...
