acritarch

acritarch
noun Etymology: Greek akritos uncertain (from a- + kritos, verbal of krinein to decide) + archē beginning — more at certain, arch- Date: 1963 any of a group of fossil one-celled marine planktonic organisms of uncertain and possibly various taxonomic affinities held to represent the earliest known eukaryotes

New Collegiate Dictionary. 2001.

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  • Acritarch — DefinitionIn general, any small, non acid soluble (i.e. non carbonate, non siliceous) organic structure that can not otherwise be accounted for is classified as an acritarch. Acritarchs include the remains of a wide range of quite different kinds …   Wikipedia

  • acritarch — acritarchous, adj. /ak ri tahrk /, n. Paleontol. any of various microfossils, of unknown biological affinities, having a central cavity enclosed by a wall of chiefly organic composition. [1963; < NL Acritarcha (neut. pl.), irreg. < Gk ákrit(os)… …   Universalium

  • acritarch — noun Any small, non acid soluble (i.e. non carbonate, non siliceous) organic fossil that cannot be classified …   Wiktionary

  • acritarch — ac·ri·tarch …   English syllables

  • acritarch — ˈakrəˌtärk noun ( s) Etymology: Greek akritos confused, uncertain (from a a (II) + kritos, verbal of krinein to separate, decide) + archē beginning more at certain archi : any of a group of fossil one celled marine planktonic organism …   Useful english dictionary

  • Cambrian explosion — The Cambrian explosion or Cambrian radiation was the seemingly rapid appearance of most major groups of complex animals around Ma|530, as evidenced by the fossil record. [http://www.ucmp.berkeley.edu/cambrian/camb.html The Cambrian Period] ]… …   Wikipedia

  • Acritarcha — Die Acritarcha (gr. ἄχριτος unsicher; αρχη Ursprung), auch Acritarchen (Sing.: ‚das Acritarch‘) stellen eine künstlich definierte Gruppe von Mikrofossilien dar, deren genaue systematische Einordnung weitgehend unbekannt ist. Zu den Acritarchen… …   Deutsch Wikipedia

  • Proterozoic — The Proterozoic (pronEng|ˌproʊtərəˈzoʊɪk) is a geological eon representing a period before the first abundant complex life on Earth. The Proterozoic Eon extended from 2500 Ma to 542.0 ± 1.0 Ma (million years ago), and is the most recent part of… …   Wikipedia

  • Doushantuo Formation — Stratigraphic range: 635–551 Ma[1] …   Wikipedia

  • Acraman crater — is a deeply eroded impact crater in the Gawler Ranges of South Australia. Its location is marked by Lake Acraman, a circular ephemeral playa lake about 20 km in diameter. The discovery of the crater and independent discovery of its ejecta were… …   Wikipedia

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