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Topic: Phanerozoic


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In the News (Tue 18 Dec 18)

  
  Phanerozoic - Wikipedia, the free encyclopedia
The Phanerozoic (occasionally Phaenerozoic) Eon is the period of geologic time during which abundant animal life has existed.
In the older literature, the term Phanerozoic is generally used as a label for the time period of interest to paleontologists.
The time span of the Phanerozoic includes the rapid emergence of a number of animal phyla; the evolution of these phyla into diverse forms; the emergence of terrestrial plants; the development of complex plants; the evolution of fish; the emergence of terrestrial animals; and the development of modern faunas.
en.wikipedia.org /wiki/Phanerozoic   (309 words)

  
 Phanerozoic -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-09-11)
The Phanerozoic (occasionally Phaenerozoic) (An immeasurably long period of time) Eon is the period of (The time of the physical formation and development of the earth (especially prior to human history)) geologic time during which abundant animal life has existed.
The time previous to the start of the Phanerozoic is called (The eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago) Precambrian.
The Phanerozoic is divided into three (A major division of geological time; an era is usually divided into two or more periods) Eras -- (From 544 million to about 230 million years ago) Paleozoic, (From 230 million to 63 million years ago) Mesozoic, and (Approximately the last 63 million years) Cenozoic.
www.absoluteastronomy.com /encyclopedia/p/ph/phanerozoic.htm   (248 words)

  
 History of Geologic Time Scale
The Phanerozoic Eon is shown along the top left side of this figure and represents the time during which the majority of macroscopic organisms, algal, fungal, plant and animal, lived.
The time before the Phanerozoic is usually referred to as the Precambrian, and exactly what qualifies as an "eon" or "era" varies somewhat depending on whom you talk to.
The Phanerozoic also consists of three major divisions...the Cenozoic, the Mesozoic, and the Paleozoic Eras.
www.ucmp.berkeley.edu /exhibit/histgeoscale.html   (789 words)

  
 The Geologic Timescale   (Site not responding. Last check: 2007-09-11)
The Phanerozoic (the third and present eon), depicted to the left, began approximately 550 million years ago (although some researchers push this date back another 20 to 40 million years).
"Phanerozoic" means "visible life," since it was believed that the start of this eon marked the first signs of life.
The Phanerozoic eon is further subdivided into three eras: the Paleozoic, Mesozoic, and Cenozoic.
www.mnh.si.edu /anthro/humanorigins/faq/gt/gt_scale.html   (250 words)

  
 Palaeos Timescale: The Phanerozoic Eon
The Phanerozoic represents a relatively brief period of half a billion years (brief that is relative to the age of the Earth and the universe) that constitutes the age of multicellular animal life on Earth.
The term Phanerozoic - "revealed life" - is generally applied to the Paleozoic, Mesozoic and Cenozoic eras; the relatively short period during which the Earth has been inhabited by multicellular organisms that leave fossil traces in the rocks.
Of the three main eras that make up the Phanerozoic, the Paleozoic is the longest and most diverse, spanning the period from very early multicellular life that only inhabited the oceans to quite advanced tetrapods* and reptiles and extensive forests on land.
www.palaeos.com /Timescale/Phanerozoic.htm   (641 words)

  
 MSN Encarta - Search Results - Phanerozoic
Phanerozoic Eon, most recent of the three eons, or major time frames, of Earth’s history (Geologic Time).
Geologists divide the history of the Earth into three eons: the Archean Eon, which lasted from around 4 billion to 2.5 billion years ago; the...
The Phanerozoic Eon is the most recent eon of the earth and is divided into the Paleozoic Era (570 million to 240 million years before present), the...
encarta.msn.com /Phanerozoic.html   (98 words)

  
 Postglacial Gravity Anomaly
It is also significant that the outcrop zone of the entire thickness of the phanerozoic stratigraphic cover of the craton lies between the outer limit of glacial erosion and the exposure of Precambrian rock of the shield.
Were the outcrop zone of the phanerozoic strata the result of long enduring subaerial dissection, it should be grossly digitate in plan, with long tongues of Precambrian exposure extending down-glacier along valleys that the river had cut through the easily eroded flat-lying phanerozoic strata of the craton.
This tendency for strata of the Phanerozoic cratonic cover to maintain their thickness to the point of exposure in the circuloid zone around the Canadian Shield is seen consistently in the four stratigraphic cross-sections across Manitoba, Saskatchewan and Alberta, presented by Gussow (1962).
www.geolab.unc.edu /faculty/white/postglacial.html   (2894 words)

  
 Phanerozoic bibliography
Cloud, P. E., Morrison, K., and Lo, S. O., 1977, New late pre-Phanerozoic and earliest Phanerozoic (?) microbiotas from Eastern Siberia: Geological Society of America, Abstracts with Programs, v.
Hallam, A., 1977, Secular changes in marine inundation of USSR and North America during the Phanerozoic: Nature, v.
Sepkoski, J. J., Bambach, R. K., Raup, D. M., and Valentine, J. Phanerozoic marine diversity and the fossil record: Nature, v.
www.talkorigins.org /origins/biblio/phanerozoic.html   (68 words)

  
 Phanerozoic Sea-Level Changes:0231074247:Hallam, Anthony:eCampus.com
In order to undertand the current state of the oceans, researchers turn to the origins of our global waters in the beginning of the Phanerozoic Eon, from 590 million years ago to the present.
Sea-level change is a prevailing topic in view of drastic climate shifts, and the greenhouse effect, which causes sea-level change by diminishing or increasing world glacier mass.
The world's major scholar in the field, Anthony Hallam brings his expertise to the subject of sea-level change in the Phanerozoic Eon in the first book exclusively devoted to the subject.
www.ecampus.com /bk_detail.asp?isbn=0231074247   (106 words)

  
 Nat' Academies Press, Tempo and Mode in Evolution: Genetics and Paleontology 50 Years After Simpson (1995)
Thus, Simpson's views of the evolutionary process were based necessarily on Phanerozoic life—the familiar progression from seaweeds to flowering plants, from trilobites to humans—a history of relatively rapidly evolving, sexually reproducing plants and animals successful because of their specialized organ systems (flowers, leaves, teeth, limbs) used to partition and exploit particular environments.
In Phanerozoic evolution, bradytelic stasis is notable principally because of its rarity (Simpson, 1944; Ruedemann, 1918, 1922a,
In contrast with Phanerozoic evolution, much of the earlier and decidedly longer Precambrian history of life was typified by the hypobradytelic evolution of dominantly microscopic, asexual, metabolically diverse, and commonly ecologically versatile prokaryotes, especially cyanobacteria.
www.nap.edu /books/0309051916/html/41.html   (6020 words)

  
 Paleoclimate | Palaeoclimate | Phanerozoic Climates
The Phanerozoic covers the last 570 Ma of Earth history, made up of three Eras, the Palaeozoic (570 to 225Ma), Mesozoic (225 to 65Ma) and Cenozoic (65Ma to present) (see appendix).
The growth of mountain ranges may affect atmospheric circulation patterns; movement of land masses into high latitude region may initiate strong ice-albedo feedbacks; variations in the rate of sea-floor spreading may alter ocean bathymetry and global carbon dioxide emissions.
The Phanerozoic has witnessed the evolution of a major tectonic cycle, involving the coming together of land masses to form a single super-continent known as Pangea (about 220Ma), followed by its disintegration, resulting in the configuration of continents that exist today.
www.global-climate-change.org.uk /5-2-2.php   (234 words)

  
 THE PHANEROZOIC SULFUR CYCLE AND ATMOSPHERIC OXYGEN   (Site not responding. Last check: 2007-09-11)
The long term Phanerozoic sulfur cycle involves the exchange of sulfur between rocks and the oceans.
Principlal processes are the weathering of pyrite, organic sulfur and CaSO4, the formation and burial of these substances in sediments, and their thermal decomposition, via metamorphism and volcanism after deep burial, with the release of sulfur-containing gases to the surface.
Reasonable results for O2 over time are obtained only if the fractionation of C and S isotopes during photosynthesis and bacterial sulfate reduction,are assumed to be a function of the level of atmospheric O2, an idea bolstered by laboratory photosynthesis experiments and by diagenetic reasoning.
gsa.confex.com /gsa/2001AM/finalprogram/abstract_17311.htm   (473 words)

  
 Special Publication 72   (Site not responding. Last check: 2007-09-11)
The prime fossil record of Phanerozoic reefs offers the opportunity to trace these patterns through space and time.
Phanerozoic Reef Patterns presents a comprehensive and up-to-date review on the history of reef building in the last 540 million years.
Reef patterns and environmental influences in the Cambrian and earliest Ordovician.
www.sepm.org /publishing/toc/SP72TOC.htm   (279 words)

  
 Lundin NGS 2004
We are sceptical to a number of plume aspects and have investigated the possible relationship between Atlantic volcanic passive margins and reactivation of pre-existing late Neoproterozoic/Phanerozoic fold belts (referred to as Phanerozoic hereafter).
Atlantic volcanic margin segments developed along reopened Phanerozoic sutures, while non-volcanic margins formed where: a) cratons were separated, b) Phanerozoic fold belts were transacted at a high angle, or c) Archean mobile belts were followed.
Thus, it appears that the natural outcome of the Wilson Cycle, when applied to the reactivation of Phanerozoic belts, is volcanic passive margins.
www.mantleplumes.org /Abstracts/Lundin_NGS_2004.html   (783 words)

  
 Gibson, L. J. --- Polyphyly and the Cambrian Explosion
Perhaps the most compelling feature of the fossil record is the sudden appearance of a wide diversity of fossils at and near the base of the Phanerozoic sediments.
First appearances of phyla and classes of metazoans (multicellular animals) are not distributed evenly throughout the geologic column, but are largely clustered at the lower end of the Phanerozoic, predominantly from the uppermost Precambrian to the Ordovician, peaking in the Cambrian.
The greatest morphological differences appear in the lower Phanerozoic rocks, while the rest of the fossil record consists largely of variations of familiar themes.
www.grisda.org /origins/52003.htm   (1273 words)

  
 Amazon.ca: Books: An Australian Phanerozoic Timescale   (Site not responding. Last check: 2007-09-11)
For the first time, correlations are established between Australian and European biozonal schemes for the entire Phanerozoic, by integrating local and international biozones, isotopic ages, and magnetic polarity intervals.
It is the first Phanerozoic scale whose time calibration is heavily weighted by modern application of isotopic dating of the 1980s and 1990s, especially variants of 40 Ar/39Ar and U/Pb zircon-dating, which have radically rescaled some parts of geologic time.
An Australian Phanerozoic Timescale gives the essential framework for resource exploration, geologic modelling, and reconstruction of past environments and land-sea configurations during the last 545 million years of earth history.
www.amazon.ca /exec/obidos/ASIN/0195539516   (318 words)

  
 Untitled Document
All geologic time prior to the Phanerozoic is often refered to as the "Precambrian." The diagram in the following link shows the Geologic Time Scale.
The Phanerozoic Eon is drawn to scale, whereas the Precambrian, because of its immensity, is not.
The Phanerozoic Eon is divided into Eras, which are further subdivided into periods (Geologic Time Scale).
www.depauw.edu /acad/geosciences/fsoster/GeoTime.htm   (1181 words)

  
 A SIGNIFICANT RELATIONSHIP BETWEEN MACROEVOLUTIONARY ORIGINATION RATES AND PHANEROZOIC PCO2 LEVELS   (Site not responding. Last check: 2007-09-11)
Phanerozoic rates of diversification of the marine fauna and modeled levels of atmospheric CO are closely correlated.
Phanerozoic rates of marine animal extinction are also correlated with atmospheric CO2 (p < 0.01).
All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
gsa.confex.com /gsa/2002AM/finalprogram/abstract_40680.htm   (347 words)

  
 Phanerozoic Geological Column
This page provides a simple stratigraphic column depicting the Phanerozoic, with a few points of interest recorded.
The end of the period is marked by one of the more profound mass extinction events of the Phanerozoic; many groups of living things died out, most famously the dinosaurs.
A meterorite impact at the end of the period may have been a contributing factor, though to what extent is still unknown.
www.peripatus.gen.nz /paleontology/colPhanerozoic.html   (533 words)

  
 Rates of Plate Movement During the Phanerozoic
Paleomagnetic evidence can be used to estimate rates of plate motion throughout the Phanerozoic, provided we accept radiometric dating and the assumption that the earth during the Phanerozoic possessed an axial dipole magnetic field more or less coinciding with the rotational poles as it does today.
Actually, this assumption seems quite well founded, since Phanerozoic APW paths seem to agree with the same sequence of rifting/drifting events inferred on other geological evidence.
YEC tectonic models in which Pangaea is rifted apart and its fragments displaced to more or less their present positions during Noah's Flood, about 4500 years ago, are not consistent with presently measured motions, with rates indicated for the Phanerozoic by radiometric data, or with the distribution of deep sea sediments.
www.geocities.com /pgspears/plate2.htm   (1613 words)

  
 CONTRASTING CHARACTERISTICS OF PROTEROZOIC AND PHANEROZOIC MANTLE TYPES: PRELIMINARY RESULTS.   (Site not responding. Last check: 2007-09-11)
Fundamental differences in the composition of Archean and Phanerozoic lithospheric mantle have been well documented over the last decade, but little attention has been paid to the nature of Proterozoic mantle and how it compares with mantle of different ages.
To establish a basis for comparison of Phanerozoic and Proterozoic mantle in Australia sampling was carried out at several localities across Tasmania.
Sampling was carried out on either side of the Tasman Line, which delineates the surface expression of the younger Palaeozoic Tasman Fold Belt in the east from the older Proterozoic Central Australia Mobile Belt in the west, to determine any differences in mantle composition beneath the two tectonic regimes.
www.es.mq.edu.au /gemoc/annrep_1997/abs97/beyer198.htm   (639 words)

  
 MICROBIAL CONTRIBUTIONS TO PHANEROZOIC REEF DEVELOPMENT   (Site not responding. Last check: 2007-09-11)
Substantial evidence from many sites suggests that stromatolites had a persistent presence in many reef (and level-bottom) habitats throughout the Phanerozoic and were not restricted to the intertidal zone nor did they function primarily as "disaster" taxa following times of global ecologic crisis.
Demise of the stromatolite reefs occurred during the Klakas orogeny, which induced catastrophic collapse of the platform and progradation of a clastic wedge in the Early Devonian.
These and other post-Cryptozoic stromatolites demonstrate the importance of microbial components in many marine environments past and present, and they contribute to a paleobiogeographic database for elucidating the conditions that were conducive (or detrimental) to Phanerozoic stromatolite growth.
gsa.confex.com /gsa/2001ESP/finalprogram/abstract_6474.htm   (349 words)

  
 Tiering at the Ohio State University
Phanerozoic tiering in suspension feeding communities on soft substrata: implications for diversity.
Echinoderm role in the history of Phanerozoic tiering in suspension feeding communities.
Early Phanerozoic development of infaunal metazoans: trace fossil evidence from the Great Basin.
www.geology.ohio-state.edu /tiering/ref.php   (3815 words)

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