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Topic: Cambrian Explosion


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  Cambrian explosion - Encyclopedia Jr, free information reference for Kids
The Cambrian explosion has proved to be difficult to study, partly because of the problems involved in matching up rocks of the same age across continents.
The rapidity of the Cambrian explosion, the lack of precursors in the fossil record, and the apparent bewildering diversity of the forms displayed by the exceptional faunas, has generated much interest from many students of evolution, including most recently from the field of Evolutionary developmental biology ("Evo-Devo").
While the general rapidity of the Cambrian explosion thus seems to remain a reality, attempts have been made to downplay the “amount” of evolution that was required to generate the taxa actually seen in the Cambrian.
www.encyclopediajr.com /wikiarticle/c/a/m/cambrian_explosion.php   (3594 words)

  
  Cambrian explosion - Wikipedia, the free encyclopedia
The Cambrian explosion has proved to be difficult to study, partly because of the problems involved in matching up rocks of the same age across continents.
The rapidity of the Cambrian explosion, the lack of precursors in the fossil record, and the apparent bewildering diversity of the forms displayed by the exceptional faunas, has generated much interest from many students of evolution, including most recently from the field of “Evo-Devo”.
While the general rapidity of the Cambrian explosion thus seems to remain a reality, attempts have been made to downplay the “amount” of evolution that was required to generate the taxa actually seen in the Cambrian.
en.wikipedia.org /wiki/Cambrian_Explosion   (3608 words)

  
 Palaeos Paleozoic: Cambrian: The Cambrian Period - 1
Laurentia stretched across the Cambrian equator, partly submerged by the Iapetus ocean, with a mostly mostly submerged Baltica and Siberia approaching from the South-East.
During the 53 million years that the Cambrian period lasted there was the sudden appearance and diversification of almost every major group (phylum) of animal life, as well as many types that later died out.
The most characteristic animals of the Cambrian period were the trilobites, a primitive form of arthropod remarkable for it's highly developed eyes (unusual in such an early organism).
www.palaeos.com /Paleozoic/Cambrian/Cambrian.htm   (2818 words)

  
 CC300: Cambrian Explosion
The Cambrian explosion was the seemingly sudden appearance of a variety of complex animals about 540 million years ago (Mya), but it was not the origin of complex life.
The length of the Cambrian explosion is ambiguous and uncertain, but five to ten million years is a reasonable estimate; some say the explosion spans forty million years or more, starting about 553 million years ago.
A "snowball earth" before the Cambrian explosion may have hindered development of complexity or kept populations down so that fossils would be too rare to expect to find today.
www.talkorigins.org /indexcc/CC/CC300.html   (1162 words)

  
 Evolution: Library: The Cambrian Explosion
But it was not as rapid as an explosion: the changes seems to have happened in a range of about 30 million years, and some stages took 5 to 10 million years.
Laid down in the middle-Cambrian, when the "explosion" had already been underway for several million years, this formation contains the first appearance in the fossil record of brachiopods, with clamlike shells, as well as trilobites, mollusks, echinoderms, and many odd animals that probably belong to extinct lineages.
Recent research suggests that the period prior to the Cambrian explosion saw the gradual evolution of a "genetic tool kit" of genes that govern developmental processes.
www.pbs.org /wgbh/evolution/library/03/4/l_034_02.html   (824 words)

  
 Life During the Cambrian Period
Finally, the Cambrian saw the appearance and/or diversification of mineralized algae of various types, such as the coralline red algae and the dasyclad green algae.
Cambrian echinoderms were predominantly unfamiliar and strange-looking types such as early edrioasteroids, eocrinoids, and helicoplacoids.
And while jawless vertebrates were present in the Cambrian, it was not until the Ordovician that armored fish became common enough to leave a rich fossil record.
www.ucmp.berkeley.edu /cambrian/camblife.html   (571 words)

  
 Cambrian Explosion
This page describes the metazoan (animal) evolutionary phenomenon popularly known as the "Cambrian explosion." The apparent discrepancy between divergence ages implied by genetic calibration techniques and a literal interpretation of the fossil record is discussed.
The Cambrian Explosion documents a real and dramatic radiation of skeletal morphologies, which might represent the parallel uptake of skeletonisation by numerous pre-existing, soft-bodied lineages or, alternatively, a rapid diversification within a relatively few already-skeletonised lineages.
Bengtson, Stefan; Zhao, Yue 1997: Fossilized Metazoan Embryos from the Earliest Cambrian.
www.peripatus.gen.nz /paleontology/CamExp.html   (3079 words)

  
 Explosion of Life: A scientist reveals details of the Cambrian explosion
Also, the animal explosion caught people's attention when the Chinese confirmed they found a genus now called Yunnanzoon that was present in the very beginning.
They say that maybe in Cambrian times the oxygen level in the atmosphere and in the oceans suddenly arose to a critical level which could support larger-sized animals.
Personally, I have an urge to popularize these ideas because although scientists are beginning to talk about the Cambrian explosion, and while a few people in the inner circle know about it, the general public isn't aware of it.
www.origins.org /articles/chien_explosionoflife.html   (2740 words)

  
 The Cambrian Period
The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record.
This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears.
It was once thought that the Cambrian rocks contained the first and oldest fossil animals, but these are now to be found in the earlier Vendian strata.
www.ucmp.berkeley.edu /cambrian/camb.html   (272 words)

  
 NewCreationism.Org - Article #8 - The Cambrian Explosion Provides Devastating Evidence against Gradual Evolution
The Cambrian Explosion is the compound term used to describe the vast number of new phyla that appear in the fossil record for the first time around 540 million years ago.
Before the Cambrian Explosion the fossil record shows that life on Earth was fairly static.
Considering the wide array of creatures found during the Cambrian explosion this can be considered at best special pleading.
www.newcreationism.org /CreationArticle8.html   (646 words)

  
 Cambrian Explosion Fossils Utah
Less well known is that the western state of Utah has similar fauna of the Cambrian Explosion.
Cambrian outcrops bearing well preserved biota of the Cambrian Explosion are found in Utah, Western Canada and California, among others.
The Middle Cambrian Wheeler, Marjum and Weeks Formations are exposed within the House Range west of Delta, Utah.
www.fossilmuseum.net /Cambrian-Explosion/Utah-Cambrian-Explosion.htm   (235 words)

  
 Encyclopedia Galactica - Ca to Cd - Human (Anglic) Revised 351st Edition
During this period there was the greatest adaptive radiation the pre-singularity Earth has seen, the Cambrian Explosion, when all existing (and many extinct) phyla of animals appear for the first time.
The end of the Cambrian saw a mass extinction, with 50% of all animal families becoming extinct, possibly due to
Cambrian period, when an unusual combination of environmental events (tectonic, atmospheric, ocean chemistry, climatic, ecological) triggered the sudden evolutionary radiation of terragen
www.orionsarm.com /eg/c/Ca-Cd.html   (3604 words)

  
 ScienceDaily: Large Gene Study Questions Cambrian Explosion
Science Daily — The ancestors of major groups of animal species began populating Earth more than 600 million years earlier than indicated by their fossil remains, according to the largest study on the subject using gene sequences, recently completed at Penn State.
The research suggests that animals have been evolving steadily into different species for at least 1200 million years, which challenges a popular theory known as the Cambrian Explosion that proposes the sudden appearance of most major animal groups, known as phyla, 530 million years ago.
Another hypothesis is that many species of animals with skeletons were living on Earth before the Cambrian period, but they were so small that their fossils have not yet been found.
www.sciencedaily.com /releases/1999/01/990121073459.htm   (992 words)

  
 V049SK The Cambrian Explosion Video Study Kit
The Cambrian explosion is a term often heard in origins debates, but seldom completely understood by the non-specialist.
The term Cambrian explosion describes the geologically sudden appearance of animals in the fossil record during the Cambrian period of geologic time.
The word explosion is used to communicate that fact that these life forms appear in an exceedingly narrow window of geologic time (no more than 5 million years).
www.arn.org /arnproducts/videos/v049sk.htm   (1583 words)

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