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
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with extinction
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 ...
Researchers reveal ancient origins of modern opossum
Other Sciences / Archaeology & Fossils
Dec 16, 2009 |
4 / 5 (2) |
0
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 ...
Late-surviving megafauna exposed by ancient DNA in frozen soil
Dec 15, 2009 |
4.5 / 5 (2) |
0
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 ...
Sucker-footed bats don't use suction after all (w/ Video)
Dec 14, 2009 |
4.3 / 5 (3) |
0
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 ...
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.
Superior Super Earths
Space & Earth / Space Exploration
Nov 30, 2009 |
4.6 / 5 (55) |
15
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 ...
Mass Extinctions, Ancient Viruses May Hold Clues to Life’s Origins
Apr 03, 2009 |
4.7 / 5 (30) |
16
(PhysOrg.com) -- Mass extinctions occur repeatedly, though irregularly, throughout Earth’s history, and occasionally these extinctions have been devastating to life on our planet - or have they? Extinction ...
Antarctica served as climatic refuge in Earth's greatest extinction event
Space & Earth / Earth Sciences
Dec 02, 2009 |
4.6 / 5 (10) |
0
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 ...
Physicists Show that Correlated Environmental Variations Can Quicken Extinctions
Jan 13, 2009 |
3.8 / 5 (6) |
5
(PhysOrg.com) -- In general, population extinction is a natural process. For one reason or another, an estimated 99.9% of all species that have lived on Earth are now extinct. However, the reasons for a species ...
Killer algae a key player in mass extinctions
Space & Earth / Earth Sciences
Oct 19, 2009 |
4.4 / 5 (17) |
4
Algae, not asteroids, were the key to the end of the dinosaurs, say two Clemson University researchers. Geologist James W. Castle and ecotoxicologist John H. Rodgers have published findings that toxin producing ...
Reptiles stood upright after mass extinction
Other Sciences / Archaeology & Fossils
Sep 15, 2009 |
4 / 5 (8) |
1
(PhysOrg.com) -- Reptiles changed their walking posture from sprawling to upright immediately after the end-Permian mass extinction, the biggest crisis in the history of life that occurred some 250 million ...
Prehistoric Cold Case Hints of Interspecies Homicide
Other Sciences / Archaeology & Fossils
Jul 20, 2009 |
4.6 / 5 (7) |
2
(PhysOrg.com) -- The wound that ultimately killed a Neandertal man between 50,000 and 75,000 years was most likely caused by a thrown spear, the kind modern humans used but Neandertals did not, according to ...
A new day dawned fast: Recovery from marine mass extinction happened much faster than thought
Space & Earth / Earth Sciences
Oct 02, 2009 |
4.8 / 5 (14) |
0
(PhysOrg.com) -- In 1979, Luis Alvarez and his collaborators stunned the world with their discovery that an asteroid impact 65 million years ago probably killed off the dinosaurs and much of the the world's ...
Geoscientist offers new evidence that meteorite did not wipe out dinosaurs
Space & Earth / Earth Sciences
May 04, 2009 |
4.5 / 5 (21) |
28
A Princeton University geoscientist who has stirred controversy with her studies challenging a popular theory that an asteroid wiped out the dinosaurs has compiled powerful new evidence asserting her position.
Crashing comets not likely the cause of Earth's mass extinctions: new research
Space & Earth / Space Exploration
Jul 30, 2009 |
3.7 / 5 (18) |
14
(PhysOrg.com) -- Scientists have debated how many mass extinction events in Earth's history were triggered by a space body crashing into the planet's surface. Most agree that an asteroid collision 65 million ...
