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Phanerozoic
Phanerozoic Derived from the Greek and meaning ‘apparent or evident life’, the term ‘Phanerozoic’ is given to the long span of geological time (eon) that has passed since the beginning of the Cambrian period, and to the rocks formed during that time (eonothem). Thus it succeeds the span known as the Cryptozoic (‘hidden life’) Eon, which covers all Precambrian (i.e. Proterozoic and Archaean) time. The terms were invented by the American stratigrapher G. H. Chadwick in 1930, and have been in general use ever since.
It is now known that the later Proterozoic rocks include fossils that are clearly evident and identifiable, but the palaeontology of Precambrian rocks is mainly obscure. Algae and other primitive plants and relatively simple animal body fossils and trace fossils (ichnofossils) of animals indicate that life was widespread and diverse in late Cryptozoic time. Then, however, something of an organic revolution took place at the beginning of the Phanerozoic when hard skeletal structures appeared in many animals for the first time. Fossilization of these forms immediately became more common and ensured the improved record of the biosphere that characterizes the Phanerozoic systems of rocks. The term ‘Precambrian’ is still used for Cryptozoic rocks, but tends to be applied loosely to formations lying beneath identified Cambrian strata and of uncertain age. The beginning of the Cambrian period, and hence of Phanerozoic time, is estimated to be around 570 million years ago. The base of the Cambrian system is defined by international agreement on palaeontological criteria. On similar lines, agreement is being sought for the base of each successive geological system. Throughout the Phanerozoic systems, fossils provide the best means of correlation and also record the progress of organic evolution over more than 500 million years. The division of the Phanerozoic into chronostratigraphic divisions—eras, periods, epochs and ages—has itself evolved over a period of about 200 years. It is based upon both lithostratigraphy and biostratigraphy and seeks to provide a basis for world correlation and the relative dating of geological events, processes, and materials. D. L. Dineley Bibliography Further readings Calder, N. (1984) Timescale: an atlas of the fourth dimension. Chatto and Windus, London. |
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Cite this article
PAUL HANCOCK and BRIAN J. SKINNER. "Phanerozoic." The Oxford Companion to the Earth. 2000. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. PAUL HANCOCK and BRIAN J. SKINNER. "Phanerozoic." The Oxford Companion to the Earth. 2000. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O112-Phanerozoic.html PAUL HANCOCK and BRIAN J. SKINNER. "Phanerozoic." The Oxford Companion to the Earth. 2000. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O112-Phanerozoic.html |
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Phanerozoic
Phanerozoic Period of geologic time comprising the Palaeozoic Mesozoic, and Cenozoic Eras, It began approximately 570 Ma ago at the start of the Cambrian Period and is marked by the accumulation of sediments containing the remains of animals with mineralized skeletons. Although the name is derived from the Greek phaneros meaning ‘visible’ and zoion meaning ‘animal’, the term is no longer used in the sense of ‘visible life’, but merely defines the base of the Cambrian.
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AILSA ALLABY and MICHAEL ALLABY. "Phanerozoic." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Phanerozoic." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O13-Phanerozoic.html AILSA ALLABY and MICHAEL ALLABY. "Phanerozoic." A Dictionary of Earth Sciences. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Phanerozoic.html |
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Phanerozoic
Phanerozoic The period of geological time that comprises the Palaeozoic, Mesozoic, and Cenozoic Eras. It began 590 Ma ago at the end of the Precambrian and is marked by the accumulation of sediments containing the remains of animals with mineralized skeletons. The name means the period of ‘visible or obvious life’, but is no longer used in this sense, merely defining the base of the Cambrian.
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MICHAEL ALLABY. "Phanerozoic." A Dictionary of Ecology. 2004. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Phanerozoic." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O14-Phanerozoic.html MICHAEL ALLABY. "Phanerozoic." A Dictionary of Ecology. 2004. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-Phanerozoic.html |
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Phanerozoic
Phanerozoic The period of geological time that comprises the Palaeozoic, Mesozoic, and Cenozoic Eras. It began 590 Ma ago at the end of the Precambrian and is marked by the accumulation of sediments containing the actual remains of plant structures. The name is derived from the Greek phaneros, meaning ‘visible’ and zoe, meaning ‘life’.
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MICHAEL ALLABY. "Phanerozoic." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Phanerozoic." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O7-Phanerozoic.html MICHAEL ALLABY. "Phanerozoic." A Dictionary of Plant Sciences. 1998. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-Phanerozoic.html |
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Phanerozoic
Phanerozoic The period of geological time that comprises the Palaeozoic, Mesozoic, and Cenozoic Eras. It began 542 Ma ago at the end of the Precambrian and is marked by the accumulation of sediments containing the remains of animals with mineralized skeletons. The name means the period of ‘visible’ or ‘obvious life’.
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Cite this article
MICHAEL ALLABY. "Phanerozoic." A Dictionary of Zoology. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Phanerozoic." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O8-Phanerozoic.html MICHAEL ALLABY. "Phanerozoic." A Dictionary of Zoology. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Phanerozoic.html |
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Phanerozoic
Phanerozoic The most recent eon of geological time, represented by rock strata containing clearly recognizable fossils. It comprises the Palaeozoic, Mesozoic, and Cenozoic eras and has extended for about 570 million years from the beginning of the Cambrian period. Compare Proterozoic.
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Cite this article
"Phanerozoic." A Dictionary of Biology. 2004. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "Phanerozoic." A Dictionary of Biology. 2004. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O6-Phanerozoic.html "Phanerozoic." A Dictionary of Biology. 2004. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-Phanerozoic.html |
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