Phanerozoic


Phanerozoic

The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the geologic timescale, and the one during which abundant animal life has existed. It covers roughly 545 million years and goes back to the time when diverse hard-shelled animals first appeared. Its name derives from the Greek meaning "visible life", referring to the large size of organisms since the Cambrian explosion. The time previous to the start of the Phanerozoic was formerly called the "Precambrian" (now divided into the Hadean, Archaean and Proterozoic eons). The exact time of the boundary between the Phanerozoic and the Proterozoic is slightly uncertain. In the 19th Century, the boundary was set at the first abundant metazoan fossils. But several hundred taxa of Proterozoic metazoa have been identified since systematic study of those forms started in the 1950s. Most geologists and paleontologists would probably set the Proterozoic-Phanerozoic boundary either at the classic point where the first trilobites and archaeocyatha appear; at the first appearance of a complex feeding burrow called "Trichophycus pedum"; or at the first appearance of a group of small, generally disarticulated, armored forms termed 'the small shelly fauna'. The three different dividing points are within a few million years of each other.

The Phanerozoic is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic. In the older literature, the term "Phanerozoic" is generally used as a label for the time period of interest to paleontologists, but that use of the term seems to be falling into disuse in more modern literature.

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. During the period covered, continents drifted about, eventually collected into a single landmass known as Pangea and then split up into the current continental landmasses.

ee also

* Geologic time scale
* Paleoclimatology
* Plate tectonics

References

*cite journal |last=Markova |first=Alexander V. |authorlink= |coauthors=Korotayev, Andrey V. |year=2007 |month= |title=Phanerozoic marine biodiversity follows a hyperbolic trend |journal=Palaeoworld |volume=16 |issue=4 |pages=311–318 |doi=10.1016/j.palwor.2007.01.002 |url= |accessdate= |quote=
*cite journal |last=Miller |first=K. G. |authorlink= |coauthors="et al." |year=2005 |month= |title=The Phanerozoic record of global sea-level change |journal=Science |volume=310 |issue=5752 |pages=1293–1298 |doi=10.1126/science.1116412 |url= |accessdate= |quote= |pmid=16311326


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  • Phanerozoic — [fan΄ər ə zō′ik] adj. [< Gr phaneros (see PHANEROGAM) + ZOIC] [sometimes p ] designating or of the geologic eon usually subdivided into the Paleozoic, Mesozoic, and Cenozoic eras designating or of the geologic eon usually subdivided into the… …   English World dictionary

  • phanerozoic — fanerozojus statusas T sritis ekologija ir aplinkotyra apibrėžtis Žemės geologijos istorijos laikotarpis, apimantis 3 geologijos eras: paleozojų, mezozojų ir kainozojų; per tą laikotarpį susidariusių uolienų kompleksas. Tęsėsi phanerozoic 570 mln …   Ekologijos terminų aiškinamasis žodynas

  • Phanerozoic — noun the period from about 5,400 million years ago until the present • Syn: ↑Phanerozoic eon, ↑Phanerozoic aeon • Instance Hypernyms: ↑eon, ↑aeon • Part Meronyms: ↑Cenozoic, ↑Cenozoic era …   Useful english dictionary

  • Phanerozoic — adjective Etymology: Greek phaneros + English 2 zoic Date: 1930 of, relating to, or being an eon of geologic history that comprises the Paleozoic, Mesozoic, and Cenozoic or the corresponding systems of rocks see geologic time table • Phanerozoic… …   New Collegiate Dictionary

  • Phanerozoic — 1. adjective Of, or relating to the geologic eon from about 570 million years ago to the present; comprises the Paleozoic, Mesozoic and Cenozoic eras. 2. noun The Phanerozoic eon …   Wiktionary

  • Phanerozoic — adj. pertaining to the Phanerozoic era (Geology) …   English contemporary dictionary

  • Phanerozoic — /fan euhr euh zoh ik/, Geol. n. 1. the eon comprising the Paleozoic, Mesozoic, and Cenozoic eras. adj. 2. of or pertaining to this eon. [1925 30; < Gk phaneró(s) manifest, visible + ZO + IC] * * * …   Universalium

  • phanerozoic —   the current eon of geologic time that began 2500m years ago …   Geography glossary

  • Phanerozoic — [ˌfan(ə)rə(ʊ) zəʊɪk] adjective Geology relating to or denoting the aeon covering the whole of time since the beginning of the Cambrian period about 570 million years ago (comprising the Palaeozoic, Mesozoic, and Cenozoic eras). Origin C19: from… …   English new terms dictionary

  • phanerozoic — phan·er·o·zo·ic …   English syllables


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