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Topic: Extinction


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  Extinction
Extinction strikes in both the land and the sea, though higher rates are generally cited among marine forms.
The Ordovician extinction was significantly the greater in terms of number of taxa killed, but did not disrupt global ecology to the extent of the end-Devonian extinction (Droser 2000).
However, other researchers observe that a mass extinction event is not necessary to explain the disappearance of the Ediacarans from the fossil record; conditions may simply have ceased to be favourable to their preservation with the arrival of more numerous and more diverse scavenging and bioturbating organisms.
www.peripatus.gen.nz /paleontology/extinction.html   (4728 words)

  
 The Great Mystery: Background
The largest would be the "Permo-Triassic" extinction, between the Permian and Triassic periods, of the Paleozoic and Mesozoic eras.
The Nature of Extinction: Extinction is not a simple event; it is not simply the death of all representatives of a group.
This is not to say that all extinction hypotheses are not science; many are excellent examples of good science, but a linkage of direct causation is a problem.
www.ucmp.berkeley.edu /diapsids/extinction.html   (1283 words)

  
  Dinosaur Extinction - Enchanted Learning Software
A mass extinction is a relatively sudden, global decrease in the diversity of life forms.
The extinctions are clustered in a short amount of geological time (a few million years is very short in terms of geological time).
The nemesis hypothesis of Raup and Sepkoski theorizes that there is a periodicity of 26 million years to mass extinctions which is caused by collisions with comets from the Oort cloud as they are perturbed in their orbits by a dark star (a companion star to the sun).
www.enchantedlearning.com /subjects/dinosaurs/extinction/index.html   (602 words)

  
  Extinction - Wikipedia, the free encyclopedia
In biology and ecology, extinction is the ceasing of existence of a species or group of taxa.
Extinction (or replacement) of species by a daughter species plays a key role in the punctuated equilibrium hypothesis of Stephen Jay Gould and Niles Eldredge.
Extinction of a species may come suddenly when an otherwise healthy species is wiped out completely, as when toxic pollution renders its entire habitat unlivable; or may occur gradually over thousands or millions of years, such as when a species gradually loses out competition for food to newer, better adapted competitors.
en.wikipedia.org /wiki/Extinction   (2507 words)

  
 Extinction event - Wikipedia, the free encyclopedia
Though there were undoubtedly mass extinctions in the Archean and Proterozoic, it is only during the Phanerozoic Eon that the emergence of bones and shells in the evolutionary tree has provided a sufficient fossil record from which to make a systematic study of extinction patterns.
The impact is postulated to have been the cause of the P-T extinction event and possibly to have initiated the break-up of the Gondwana supercontinent, creating the tectonic rift that began Australia's migration northward, away from Antarctica.
The extinction of many megafauna near the end of the most recent ice age is also sometimes considered a part of the Holocene extinction event.
en.wikipedia.org /wiki/Extinction_event   (1715 words)

  
 Palaeos Ecology : Extinction : Extinction   (Site not responding. Last check: )
The background extinction data displays two patterns: First there is an apparent decline in extinction intensity values through the Phanerozoic; very high rates of extinction seemed to be 'normal' for the early Paleozoic, gradually dropping away to levels around 5 to 10% from about the Jurassic onwards.
Extinction strikes in both the land and the sea, though higher rates are generally cited among marine forms.
However, other researchers observe that a mass extinction event is not necessary to explain the disappearance of the Ediacarans from the fossil record; conditions may simply have ceased to be favourable to their preservation with the arrival of more numerous and more diverse scavenging and bioturbating organisms.
www.palaeos.com /Ecology/Extinctions/Extinction.html   (4100 words)

  
 Impact of Deforestation—Extinction
Although great extinctions have occurred in the past, none has occurred as rapidly or has been so much the result of the actions of a single species.
The extinction rate of today may be 1,000 to 10,000 times the biological normal, or background, extinction rate of 1-10 species extinctions per year.
The extinction of small populations, either endangered or isolated from the larger gene pool by fragmentation or natural barriers like water or mountain ranges, is the best modeled and understood form of extinction.
rainforests.mongabay.com /0908.htm   (1939 words)

  
 Extinction - Memory Alpha, the Star Trek Wiki   (Site not responding. Last check: )
Extinction is a term for the condition of a species of which there are no currently living members.
Extinctions have occurred naturally through the course of evolution on many worlds, however some species have become extinct through unnatural means.
This extinction was reversed in 2373 when crew members of the USS Defiant traveled to the year 2267 and brought back at least one tribble.
memory-alpha.org /en/wiki/Extinction   (580 words)

  
 ClickerSolutions Training Articles -- Extinction
Extinction is a “non event.” You didn’t add or take away – you simply did nothing.
Extinction is a "NON-EVENT." It is lack of reinforcement.
Extinction is effective only when the behavior is in no way self-reinforcing to the learner.
www.clickersolutions.com /articles/2003/extinction.htm   (859 words)

  
 Articles / Impact / Extinction - Institute for Creation Research
There are extinctions in historical times which are due to depredations of man or stronger animals upon weaker ones.
The dinosaur extinction is the best known of all disappearances, and it occurred at the close of the Cretaceous Period in a relatively short period of time.
Valentine says, "in summary, the most likely causes of mass extinction appear to be those factors which are natural regulators of diversity under normal circumstances and which have effects that pervade the entire planet." His catastrophe is related to tectonic processes.
www.icr.org /index.php?module=articles&action=view&ID=167   (1748 words)

  
 The Sixth Extinction by Niles Eldredge, Ph.D.
At first glance, the physically caused extinction events of the past might seem to have little or nothing to tell us about the current Sixth Extinction, which is a patently human-caused event.
The invention of agriculture accelerated the pace of the Sixth Extinction.
Conservation measures, sustainable development, and, ultimately, stabilization of human population numbers and consumption patterns seem to offer some hope that the Sixth Extinction will not develop to the extent of the third global extinction, some 245 mya, when 90% of the world's species were lost.
www.actionbioscience.org /newfrontiers/eldredge2.html   (2629 words)

  
 Extinction
Of all the causes of indirect extinction the most widespread and devastating must be the destruction of habitat.
Suddenly, the word EXTINCTION has not one, but several possible definitions depending upon the species being studied or discussed and the reason for its decline or extermination.
There are many absorbing activities linked with the study of extinction ranging from simple model making and artwork to detailed studies of ecosytems, or deductions concerning climatic changes which brought the Age of Reptiles to a comparatively abrupt end.
www.yptenc.org.uk /docs/factsheets/env_facts/extinction.html   (837 words)

  
 Catastrophism and Mass Extinctions
Asteroids of Death by E.S. Matalka discusses the asteroid impact hypothesis for the extinction of the dinosaurs.
Carriers of Extinction by Carl Zimmer suggests that the megafaunal extinctions at the end of the last ice age were caused by pathogens carried by migrating humans.
Extinctions: Cycles of Life and Death Through Time from the Hooper Virtual Paleontological Museum discusses the asteroid impact and volcano hypotheses for the end-Cretaceous extinction.
www.pibburns.com /catastro/extinct.htm   (1469 words)

  
 March 2, 2004: The Sixth Great Extinction
This potential sixth great extinction is unique in that it is caused largely by the activities of a single species.
The average extinction rate is now some 1,000 to 10,000 times faster than the rate that prevailed over the past 60 million years.
While this may be the first time in history that a single species can precipitate a mass extinction event, it is also the first time in history that a single species can act to prevent it.
www.earth-policy.org /Updates/Update35.htm   (1332 words)

  
 Planet of Weeds
The concept of mass extinction implies a biological crisis that spanned large parts of the planet and, in a relatively short time, eradicated a sizable number of species from a variety of groups.
The most recent was the Cretaceous extinction (sometimes called the K-T event because it defines the boundary between two geologic periods, with K for Cretaceous, never mind why, and T for Tertiary), familiar even to schoolchildren because it ended the age of dinosaurs.
Jablonski himself, in a 1991 paper published in Science, extrapolated from past mass extinctions to our current one and suggested that human activities are likely to take their heaviest toll on narrowly endemic species, while causing fewer extinctions among those species that are broadly adapted and broadly distributed.
ranprieur.com /readings/weeds.html   (7034 words)

  
 Archived conservation news articles on Extinction
Congo's hippos being poached to extinction by former millias from...
One way to preserve the bird from extinction was by an informal village ban on the use of guns and spears to hunt the egret, a compromise measure that meant...
NEW DELHI: The biggest mass extinction in the history of the Earth some 250m years ago was caused by global warming and not by the impact of an asteroid or...
conservation.mongabay.com /news/Extinction.htm   (12195 words)

  
 Evolution: Extinction: A Modern Mass Extinction?
He has conducted extensive research on the rates and causes of species extinction, on the nature of ecological communities, and on the impacts and management of introduced species (those who migrate to a new area).
Even though it's hard to compare past extinction rates with that of the present, given missing data from the past, we do know how to identify extinction periods: the elevation of extinction rates in those periods are at least a hundred-fold over the slow "background" rate of "normal" extinction.
But for groups that we know well, knowledge of very recent species extinctions -- and for current species, their ranges and the threats to them -- allows us to be certain that extinction rates are comparable to those of the great past extinctions.
www.pbs.org /wgbh/evolution/extinction/massext/statement_03.html   (490 words)

  
 Late Pleistocene Extinctions
Before this extinction the diversity of large mammals in North America was similar to that of modern Africa.
The environmental changes might have caused extinction by eliminating food sources, disrupting birth schedules, or exposing animals to climatic conditions to which they were not adapted.
The third hypothesis to account for large scale extinctions at the end of the Pleistocene is based on the idea of hyperdiseases, which are highly infectious diseases.
www.museum.state.il.us /exhibits/larson/LP_extinction.html   (667 words)

  
 The New Atlantis - The Rhetoric of Extinction - Charles T. Rubin
In the rhetoric of extinction, it seems that the only bad people are those who would prohibit the development of these new technologies.
Mindless optimism of this sort is vital to the rhetoric of extinction, intimately bound up as it is with the effort to define the issue of the future of science and technology as entirely a question of individual choice.
Yet the rhetoric of extinction would have us believe that the restraints and controls of the past are of no value in relation to the post-human future.
www.thenewatlantis.com /archive/11/rubin.htm   (4160 words)

  
 FirstScience - Extinction!
Even after decades of intense study, researchers are still arguing over the cause of the best-known mass extinction, the ‘death of the dinosaurs.’ And there’s a topical slant in the idea that - even today - species are regarded as "endangered" if they are relatively susceptible to extinction.
For all that is said in popular books, articles and television programmes, the study of extinction is a surprisingly problematic and young field of inquiry.
Extinction is one of the most common observations in palaeontology, but it remains very difficult to understand precisely why a particular ancient plant or animal species went extinct.
www.firstscience.com /SITE/articles/macleod.asp   (484 words)

  
 Open Directory - Science: Earth Sciences: Paleontology: Extinction   (Site not responding. Last check: )
Extinction - A number of extinction concepts are discussed and loosely defined, followed by a survey of some important extinction and "extinction-like" events, primarily from the Phanerozoic.
Extinctions: Cycles of Life and Death Through Time - Covers patterns and periodicity of extinction, with discussions of major mass extinctions and minor extinction events.
The Late Devonian Mass Extinction - A professional technical paper discussing whether the Late Devonian (Frasnian-Famennian) mass extinction was initiated by an extraterrestrial impact or an earth-bound event.
dmoz.org /Science/Earth_Sciences/Paleontology/Extinction   (191 words)

  
 Mass Extinction Underway | Biodiversity Crisis | Global Species Loss
A majority of the nation's biologists are convinced that a "mass extinction" of plants and animals is underway that poses a major threat to humans in the next century, yet most Americans are only dimly aware of the problem, a poll says.
The rapid disappearance of species was ranked as one of the planet's gravest environmental worries, surpassing pollution, global warming and the thinning of the ozone layer, according to the survey of 400 scientists commissioned by New York's American Museum of Natural History.
Yemen's Wildlife on Brink of Extinction (Yemen Observer)
www.well.com /user/davidu/extinction.html   (3082 words)

  
 Dinosaur Extinction Page
Probably the most famous is the extinction that finally saw the end of the dinosaurs reign on the Earth, 65 million years ago.
Whatever caused the death of the dinosaurs also caused the death of around 70% of all of the species on the Earth.
As is common with all mass extinctions there would have a sudden evolutionary burst as new species developed.
web.ukonline.co.uk /a.buckley/dino.htm   (2059 words)

  
 End of Permian Extinction--The largest extinction of all time, Educational Resources for K-16
Short explanation of mass extinctions, their cause and effect, and a discussion of the Permian extinction.
Nontechnical synopsis of research article that interprets carbon isotope data as indicating the end-Permian extinction was caused by a giant methane outburst from gas hydrates in the ocean.
Research into the idea that methane is a prime suspect for the greatest mass extinction of all time are increasingly common.
www.uky.edu /KGS/education/EndPermian.htm   (434 words)

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