Cambrian - wikipedia Cambrian Not to be confused with Cambria or Cumbria. For other uses, see Cambrian ( disambiguation ). Cambrian Period 541 -- 485.4 million years ago PreЄ Є O Pg Mean atmospheric O content over period duration c. 12.5 vol % ( 63 % of modern level Mean atmospheric CO content over period duration c. 4500 ppm ( 16 times pre-industrial level ) Mean surface temperature over period duration c. 21 ° C ( 7 ° C above modern level ) Sea level ( above present day ) Rising steadily from 30m to 90m Key events in the Cambrian view discuss edit - 550 -- -- - 540 -- -- - 530 -- -- - 520 -- -- - 510 -- -- - 500 -- -- - 490 -- -- o p r o r o z o i l o z o i Ediacaran m r i n Ordovician r r n u i n r i s r i s u r o n g i n Fortunian `` Stage 2 '' `` Stage 3 '' `` Stage 4 '' `` Stage 5 '' Drumian Guzhangian Paibian Jiangshanian `` Stage 10 '' * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Baykonurian glaciation Baykonurian glaciation * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ← Orsten Fauna ← Burgess Shale ← Kaili biota ← Archaeocyatha extinction ← Emu Bay Shale ← Sirius Passet biota ← Chengjiang biota ← First Trilobites ← SSF diversification, first brachiopods & archaeocyatha ← First halkieriids, mollusсs, hyoliths SSF ← Treptichnus pedum trace Large negative peak δ 13C excursion ← First Cloudina & Namacalathus mineral tubular fossils Stratigraphic scale of the ICS subdivisions and Precambrian / Cambrian boundary. The Cambrian Period ( / ˈkæmbriən / or / ˈkeɪmbriən / ) was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago ( mya ) to the beginning of the Ordovician Period 485.4 mya. Its subdivisions, and its base, are somewhat in flux. The period was established ( as `` Cambrian series '' ) by Adam Sedgwick, who named it after Cambria, the Latinised form of Cymru, the Welsh name for Wales, where Britain 's Cambrian rocks are best exposed. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where `` soft '' parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods. The Cambrian marked a profound change in life on Earth ; prior to the Cambrian, the majority of living organisms on the whole were small, unicellular and simple ; the Precambrian Charnia being exceptional. Complex, multicellular organisms gradually became more common in the millions of years immediately preceding the Cambrian, but it was not until this period that mineralized -- hence readily fossilized -- organisms became common. The rapid diversification of lifeforms in the Cambrian, known as the Cambrian explosion, produced the first representatives of all modern animal phyla. Phylogenetic analysis has supported the view that during the Cambrian radiation, metazoa ( animals ) evolved monophyletically from a single common ancestor : flagellated colonial protists similar to modern choanoflagellates. Although diverse life forms prospered in the oceans, the land is thought to have been comparatively barren -- with nothing more complex than a microbial soil crust and a few molluscs that emerged to browse on the microbial biofilm known to have been present. Most of the continents were probably dry and rocky due to a lack of vegetation. Shallow seas flanked the margins of several continents created during the breakup of the supercontinent Pannotia. The seas were relatively warm, and polar ice was absent for much of the period. Contents 1 Stratigraphy 1.1 Subdivisions 1.2 Dating the Cambrian 2 Paleogeography 3 Climate 4 Flora 5 Oceanic life 6 Symbol 7 Gallery 8 See also 9 References 10 Further reading 11 External links Stratigraphy Further information : Stratigraphy of the Cambrian Despite the long recognition of its distinction from younger Ordovician Period rocks and older Precambrian Supereon rocks, it was not until 1994 that this time period was internationally ratified. The base of the Cambrian lies atop a complex assemblage of trace fossils known as the Treptichnus pedum assemblage. The use of Treptichnus pedum, a reference ichnofossil to mark the lower boundary of the Cambrian, is difficult as the occurrence of very similar trace fossils belonging to the Treptichnids group are found well below the T. pedum in Namibia, Spain and Newfoundland, and possibly, in the western USA. The stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, and probably in Spain. Subdivisions The Cambrian Period followed the Ediacaran Period and was followed by the Ordovician Period. The Cambrian is divided into four epochs ( series ) and ten ages ( stages ). Currently only two series and five stages are named and have a GSSP. Because the international stratigraphic subdivision is not yet complete, many local subdivisions are still widely used. In some of these subdivisions the Cambrian is divided into three epochs with locally differing names -- the Early Cambrian ( Caerfai or Waucoban, 541 ± 1.0 to 509 ± 1.7 mya ), Middle Cambrian ( St Davids or Albertan, 509 ± 1.0 to 497 ± 1.7 mya ) and Furongian ( 497 ± 1.0 to 485.4 ± 1.7 mya ; also known as Late Cambrian, Merioneth or Croixan ). Rocks of these epochs are referred to as belonging to the Lower, Middle, or Upper Cambrian. Trilobite zones allow biostratigraphic correlation in the Cambrian. Each of the local epochs is divided into several stages. The Cambrian is divided into several regional faunal stages of which the Russian - Kazakhian system is most used in international parlance : Chinese North American Russian - Kazakhian Australian Regional m r i n Furongian Ibexian ( part ) Ayusokkanian Datsonian Dolgellian ( Trempealeauan, Fengshanian ) Payntonian Sunwaptan Sakian Iverian Ffestiniogian ( Franconian, Changshanian ) Steptoan Aksayan Idamean Maentwrogian ( Dresbachian ) Marjuman Batyrbayan Mindyallan Cambrian Series 3 Maozhangian Mayan Boomerangian Zuzhuangian Delamaran Amgan Undillian Zhungxian Florian Templetonian Dyeran Ordian Cambrian Series 2 Longwangmioan Toyonian Lenian Changlangpuan Montezuman Botomian Qungzusian Atdabanian Terreneuvian Meishuchuan Jinningian Placentian Tommotian Nemakit - Daldynian * Cordubian Precambrian Sinian Hadrynian Nemakit - Daldynian * Sakharan Adeladean * In Russian scientific thought the lower boundary of the Cambrian is suggested to be defined at the base of the Tommotian Stage which is characterized by diversification and global distribution of organisms with mineral skeletons and the appearance of the first Archaeocyath bioherms. Dating the Cambrian Archeocyathids from the Poleta formation in the Death Valley area The International Commission on Stratigraphy list the Cambrian period as beginning at 541 million years ago and ending at 485.4 million years ago. The lower boundary of the Cambrian was originally held to represent the first appearance of complex life, represented by trilobites. The recognition of small shelly fossils before the first trilobites, and Ediacara biota substantially earlier, led to calls for a more precisely defined base to the Cambrian period. After decades of careful consideration, a continuous sedimentary sequence at Fortune Head, Newfoundland was settled upon as a formal base of the Cambrian period, which was to be correlated worldwide by the earliest appearance of Treptichnus pedum. Discovery of this fossil a few metres below the GSSP led to the refinement of this statement, and it is the T. pedum ichnofossil assemblage that is now formally used to correlate the base of the Cambrian. This formal designation allowed radiometric dates to be obtained from samples across the globe that corresponded to the base of the Cambrian. Early dates of 570 million years ago quickly gained favour, though the methods used to obtain this number are now considered to be unsuitable and inaccurate. A more precise date using modern radiometric dating yield a date of 541 ± 0.3 million years ago. The ash horizon in Oman from which this date was recovered corresponds to a marked fall in the abundance of carbon - 13 that correlates to equivalent excursions elsewhere in the world, and to the disappearance of distinctive Ediacaran fossils ( Namacalathus, Cloudina ). Nevertheless, there are arguments that the dated horizon in Oman does not correspond to the Ediacaran - Cambrian boundary, but represents a facies change from marine to evaporite - dominated strata -- which would mean that dates from other, more suitable sections, ranging from 544 or 542 Ma, are more suitable. Paleogeography Plate reconstructions suggest a global supercontinent, Pannotia, was in the process of breaking up early in the period, with Laurentia ( North America ), Baltica, and Siberia having separated from the main supercontinent of Gondwana to form isolated land masses. Most continental land was clustered in the Southern Hemisphere at this time, but was drifting north. Large, high - velocity rotational movement of Gondwana appears to have occurred in the Early Cambrian. With a lack of sea ice -- the great glaciers of the Marinoan Snowball Earth were long melted -- the sea level was high, which led to large areas of the continents being flooded in warm, shallow seas ideal for sea life. The sea levels fluctuated somewhat, suggesting there were ' ice ages ', associated with pulses of expansion and contraction of a south polar ice cap. In Baltoscandia a Lower Cambrian transgression transformed large swathes of the Sub-Cambrian peneplain into a epicontinental sea. Climate The Earth was generally cold during the early Cambrian, probably due to the ancient continent of Gondwana covering the South Pole and cutting off polar ocean currents. However, average temperatures were 7 degrees Celsius higher than today. There were likely polar ice caps and a series of glaciations, as the planet was still recovering from an earlier Snowball Earth. It became warmer towards the end of the period ; the glaciers receded and eventually disappeared, and sea levels rose dramatically. This trend would continue into the Ordovician period. Flora Although there were a variety of macroscopic marine plants no land plant ( embryophyte ) fossils are known from the Cambrian. However, biofilms and microbial mats were well developed on Cambrian tidal flats and beaches 500 mya., and microbes forming microbial Earth ecosystems, comparable with modern soil crust of desert regions, contributing to soil formation. Oceanic life Life timeline view discuss edit - 4500 -- -- - 4000 -- -- - 3500 -- -- - 3000 -- -- - 2500 -- -- - 2000 -- -- - 1500 -- -- - 1000 -- -- - 500 -- -- 0 -- water Single - celled life photosynthesis Eukaryotes Multicellular life Arthropods Molluscs Plants Dinosaurs Mammals Flowers Birds Primates ← Earliest Earth ( − 4540 ) ← Earliest water ← Earliest life ← LHB meteorites ← Earliest oxygen ← Atmospheric oxygen ← Oxygen crisis ← Earliest sexual reproduction ← Earliest plants ← Ediacara biota ← Cambrian explosion ← Tetrapoda ← Earliest apes h n r o z o i r o r o z o i r h n d n Pongola Huronian Cryogenian Andean Karoo Quaternary ice ages Axis scale : million years Also see : Human timeline and Nature timeline Main article : Cambrian explosion Most animal life during the Cambrian was aquatic. Trilobites were once assumed to be the dominant life form at that time, but this has proven to be incorrect. Arthropods were by far the most dominant animals in the ocean, but trilobites were only a minor part of the total arthropod diversity. What made them so apparently abundant was their heavy armor reinforced by calcium carbonate ( CaCO ), which fossilized far more easily than the fragile chitinous exoskeletons of other arthropods, leaving numerous preserved remains. The period marked a steep change in the diversity and composition of Earth 's biosphere. The Ediacaran biota suffered a mass extinction at the start of the Cambrian Period, which corresponded to an increase in the abundance and complexity of burrowing behaviour. This behaviour had a profound and irreversible effect on the substrate which transformed the seabed ecosystems. Before the Cambrian, the sea floor was covered by microbial mats. By the end of the Cambrian, burrowing animals had destroyed the mats in many areas through bioturbation, and gradually turned the seabeds into what they are today. As a consequence, many of those organisms that were dependent on the mats became extinct, while the other species adapted to the changed environment that now offered new ecological niches. Around the same time there was a seemingly rapid appearance of representatives of all the mineralized phyla except the Bryozoa, which appeared in the Lower Ordovician. However, many of those phyla were represented only by stem - group forms ; and since mineralized phyla generally have a benthic origin, they may not be a good proxy for ( more abundant ) non-mineralized phyla. A reconstruction of Margaretia dorus from the Burgess Shale, which were once believed to be green algae, but are now understood to represent hemichordates. While the early Cambrian showed such diversification that it has been named the Cambrian Explosion, this changed later in the period, when there occurred a sharp drop in biodiversity. About 515 million years ago, the number of species going extinct exceeded the number of new species appearing. Five million years later, the number of genera had dropped from an earlier peak of about 600 to just 450. Also, the speciation rate in many groups was reduced to between a fifth and a third of previous levels. 500 million years ago, oxygen levels fell dramatically in the oceans, leading to hypoxia, while the level of poisonous hydrogen sulfide simultaneously increased, causing another extinction. The later half of Cambrian was surprisingly barren and show evidence of several rapid extinction events ; the stromatolites which had been replaced by reef building sponges known as Archaeocyatha, returned once more as the archaeocyathids became extinct. This declining trend did not change until the Great Ordovician Biodiversification Event. Some Cambrian organisms ventured onto land, producing the trace fossils Protichnites and Climactichnites. Fossil evidence suggests that euthycarcinoids, an extinct group of arthropods, produced at least some of the Protichnites. Fossils of the track - maker of Climactichnites have not been found ; however, fossil trackways and resting traces suggest a large, slug - like mollusc. In contrast to later periods, the Cambrian fauna was somewhat restricted ; free - floating organisms were rare, with the majority living on or close to the sea floor ; and mineralizing animals were rarer than in future periods, in part due to the unfavourable ocean chemistry. Many modes of preservation are unique to the Cambrian, and some preserve soft body parts, resulting in an abundance of Lagerstätten. Symbol The United States Federal Geographic Data Committee uses a `` barred capital C '' ⟨ Ꞓ ⟩ character to represent the Cambrian Period. The Unicode character is U + A792 Ꞓ LATIN CAPITAL LETTER C WITH BAR. Gallery Stromatolites of the Pika Formation ( Middle Cambrian ) near Helen Lake, Banff National Park, Canada Trilobites were very common during this time Anomalocaris was an early marine predator, among the various arthropods of the time. Pikaia was an early chordate from the Middle Cambrian Opabinia was a creature with an unusual body plan ; it was probably related to arthropods Protichnites were the trackways of arthropods that walked Cambrian beaches. Hallucigenia is maybe an early ancestor of the Velvet worms. Reconstructions of H. sparsa, H. hongmeia, and H. fortis Size comparison of different Cambrian species See also Part of a series on The Cambrian explosion Fossil localities Burgess Shale Chengjiang Sirius Passet Doushantuo Key organisms Ediacara biota Kimberella Vernanimalcula Burgess - type Marrella Anomalocaridids Halwaxiids Opabinia Odontogriphus Small shelly fauna Helcionellids Evolutionary concepts Trends Cambrian substrate revolution Themes Cladistics Convergent evolution Stem and crown groups Cambro - Ordovician extinction event -- circa 488 mya Dresbachian extinction event -- circa 502 mya End Botomian extinction event -- circa 517 mya List of fossil sites ( with link directory ) Type locality ( geology ), the locality where a particular rock type, stratigraphic unit, fossil or mineral species is first identified hide Modes of preservation in the Cambrian Exceptional Orsten Doushantuo type Bitter Springs type Burgess Shale type Beecher 's Trilobite Bed type Ediacaran type Conventional Small shelly fossils Acritarchs Trace fossils References Jump up ^ Image : Sauerstoffgehalt - 1000mj. svg Jump up ^ File : OxygenLevel - 1000ma. svg Jump up ^ Image : Phanerozoic Carbon Dioxide. png Jump up ^ Image : All palaeotemps. png Jump up ^ Haq, B.U. ; Schutter, SR ( 2008 ). `` A Chronology of Paleozoic Sea - Level Changes ''. 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Jump up ^ Powell, C.M. ; Dalziel, I.W.D. ; Li, Z.X. ; McElhinny, M.W. ( 1995 ). `` Did Pannotia, the latest Neoproterozoic southern supercontinent, really exist ''. Eos, Transactions, American Geophysical Union. 76 : 46 -- 72. Jump up ^ Scotese, C.R. ( 1998 ). `` A tale of two supercontinents : the assembly of Rodinia, its break - up, and the formation of Pannotia during the Pan-African event ''. Journal of African Earth Sciences. 27 ( 1A ) : 171. Bibcode : 1998JAfES... 27... 1A. doi : 10.1016 / S0899 - 5362 ( 98 ) 00028 - 1. ^ Jump up to : Mckerrow, W.S. ; Scotese, C.R. ; Brasier, M.D. ( 1992 ). `` Early Cambrian continental reconstructions ''. Journal of the Geological Society. 149 ( 4 ) : 599 -- 606. doi : 10.1144 / gsjgs. 149.4. 0599. Jump up ^ Mitchell, R.N. ; Evans, D.A.D. ; Kilian, T.M. ( 2010 ). `` Rapid Early Cambrian rotation of Gondwana ''. Geology. 38 ( 8 ) : 755. Bibcode : 2010Geo... 38... 755M. doi : 10.1130 / G30910. 1. Jump up ^ Smith, A.G. ( 2008 ). `` Neoproterozoic time scales and stratigraphy ''. Geol. Soc. ( Special publication ). Jump up ^ Brett, C.E. ; Allison, P.A. ; Desantis, M.K. ; Liddell, W.D. ; Kramer, A. ( 2009 ). `` Sequence stratigraphy, cyclic facies, and lagerstätten in the Middle Cambrian Wheeler and Marjum Formations, Great Basin, Utah ''. Palaeogeography, Palaeoclimatology, Palaeoecology. 277 : 9 -- 33. doi : 10.1016 / j. palaeo. 2009.02. 010. Jump up ^ Nielsen, Arne Thorshøj ; Schovsbo, Niels Hemmingsen ( 2011 ). `` The Lower Cambrian of Scandinavia : Depositional environment, sequence stratigraphy and palaeogeography ''. Earth - Science Reviews. 107 ( 3 -- 4 ) : 207 -- 310. doi : 10.1016 / j. earscirev. 2010.12. 004. Jump up ^ Schieber et al., 2007, pp. 53 -- 71. Jump up ^ Retallack, G.J. ( 2008 ). `` Cambrian palaeosols and landscapes of South Australia ''. Alcheringa. 55 ( 8 ) : 1083 -- 1106. Bibcode : 2008AuJES... 55.1083 R. doi : 10.1080 / 08120090802266568. Jump up ^ `` Greening of the Earth pushed way back in time ''. Jump up ^ `` Cambrian HSU NHM ''. Jump up ^ `` 3 Evolving Respiratory Systems as a Cause of the Cambrian Explosion - Out of Thin Air : Dinosaurs, Birds, and Earth 's Ancient Atmosphere - The National Academies Press ''. doi : 10.17226 / 11630. Jump up ^ Perkins, Sid ( 23 September 2013 ). `` As the worms churn ''. Jump up ^ Taylor, P.D. ; Berning, B. ; Wilson, M.A. ( 2013 ). `` Reinterpretation of the Cambrian ' bryozoan ' Pywackia as an octocoral ''. Journal of Paleontology. 87 ( 6 ) : 984 -- 990. doi : 10.1666 / 13 - 029. Jump up ^ Budd, G.E. ; Jensen, S. ( 2000 ). `` A critical reappraisal of the fossil record of the bilaterian phyla ''. Biological Reviews of the Cambridge Philosophical Society. 75 ( 2 ) : 253 -- 95. doi : 10.1111 / j. 1469 - 185X. 1999. tb00046. x. PMID 10881389. Jump up ^ Nanglu, Karma ; Caron, Jean - Bernard ; Conway Morris, Simon ; Cameron, Christopher B. ( 2016 ). `` Cambrian suspension - feeding tubicolous hemichordates ''. BMC Biology. 14. doi : 10.1186 / s12915 - 016 - 0271 - 4. Jump up ^ The Ordovician : Life 's second big bang Jump up ^ Marshall, Michael. `` Oxygen crash led to Cambrian mass extinction ''. Jump up ^ Collette & Hagadorn, 2010. Jump up ^ Collette, Gass & Hagadorn, 2012 Jump up ^ Yochelson & Fedonkin, 1993. Jump up ^ Getty & Hagadorn, 2008. ^ Jump up to : Munnecke, A. ; Calner, M. ; Harper, D.A.T. ; Servais, T. ( 2010 ). `` Ordovician and Silurian sea - water chemistry, sea level, and climate : A synopsis ''. Palaeogeography, Palaeoclimatology, Palaeoecology. 296 ( 3 -- 4 ) : 389 -- 413. doi : 10.1016 / j. palaeo. 2010.08. 001. Jump up ^ Federal Geographic Data Committee, ed. ( August 2006 ). FGDC Digital Cartographic Standard for Geologic Map Symbolization FGDC - STD - 013 - 2006 ( PDF ). U.S. Geological Survey for the Federal Geographic Data Committee. p. A -- 32 -- 1. Retrieved 23 August 2010. Jump up ^ Priest, Lorna A. ; Iancu, Laurentiu ; Everson, Michael ( October 2010 ). `` Proposal to Encode C WITH BAR '' ( PDF ). Retrieved 6 April 2011. Jump up ^ Unicode Character ' LATIN CAPITAL LETTER C WITH BAR ' ( U + A792 ). fileformat.info. Accessed 15 Jun 2015 Further reading Wikisource has original works on the topic : Paleozoic # Cambrian Amthor, J.E. ; Grotzinger, John P. ; Schröder, Stefan ; Bowring, Samuel A. ; Ramezani, Jahandar ; Martin, Mark W. ; Matter, Albert ( 2003 ). `` Extinction of Cloudina and Namacalathus at the Precambrian - Cambrian boundary in Oman ''. Geology. 31 ( 5 ) : 431 -- 434. Bibcode : 2003Geo... 31... 431A. doi : 10.1130 / 0091 - 7613 ( 2003 ) 031 < 0431 : EOCANA > 2.0.CO ; 2. Collette, J.H. ; Gass, K.C. ; Hagadorn, J.W. ( 2012 ). `` Protichnites eremita unshelled ? Experimental model - based neoichnology and new evidence for a euthycarcinoid affinity for this ichnospecies ''. Journal of Paleontology. 86 ( 3 ) : 442 -- 454. doi : 10.1666 / 11 - 056.1. Collette, J.H. ; Hagadorn, J.W. ( 2010 ). `` Three - dimensionally preserved arthropods from Cambrian Lagerstatten of Quebec and Wisconsin ''. Journal of Paleontology. 84 ( 4 ) : 646 -- 667. doi : 10.1666 / 09 - 075.1. Getty, P.R. ; Hagadorn, J.W. ( 2008 ). `` Reinterpretation of Climactichnites Logan 1860 to include subsurface burrows, and erection of Musculopodus for resting traces of the trailmaker ''. Journal of Paleontology. 82 ( 6 ) : 1161 -- 1172. doi : 10.1666 / 08 - 004.1. Gould, S.J. ; Wonderful Life : the Burgess Shale and the Nature of Life ( New York : Norton, 1989 ) Ogg, J. ; June 2004, Overview of Global Boundary Stratotype Sections and Points ( GSSPs ) https://web.archive.org/web/20060423084018/http://www.stratigraphy.org/gssp.htm Accessed 30 April 2006. Owen, R. ( 1852 ). `` Description of the impressions and footprints of the Protichnites from the Potsdam sandstone of Canada ''. Geological Society of London Quarterly Journal. 8 : 214 -- 225. doi : 10.1144 / GSL. JGS. 1852.008. 01 - 02.26. Peng, S. ; Babcock, L.E. ; Cooper, R.A. ( 2012 ). `` The Cambrian Period ''. The Geologic Time Scale ( PDF ). Schieber, J. ; Bose, P.K. ; Eriksson, P.G. ; Banerjee, S. ; Sarkar, S. ; Altermann, W. ; Catuneau, O. ( 2007 ). Atlas of Microbial Mat Features Preserved within the Clastic Rock Record. Elsevier. pp. 53 -- 71. Yochelson, E.L. ; Fedonkin, M.A. ( 1993 ). `` Paleobiology of Climactichnites, and Enigmatic Late Cambrian Fossil '' ( Free full text ). Smithsonian Contributions to Paleobiology. 74 ( 74 ) : 1 -- 74. doi : 10.5479 / si. 00810266.74. 1. External links Wikimedia Commons has media related to Cambrian. Cambrian period on In Our Time at the BBC. Biostratigraphy -- includes information on Cambrian trilobite biostratigraphy Dr. Sam Gon 's trilobite pages ( contains numerous Cambrian trilobites ) Examples of Cambrian Fossils Paleomap Project Report on the web on Amthor and others from Geology vol. 31 Weird Life on the Mats Geologic history of Earth Cenozoic era1 ( present -- 66.0 Mya ) Quaternary ( present -- 2.588 Mya ) Holocene ( present -- 11.784 kya ) Pleistocene ( 11.784 kya -- 2.588 Mya ) Neogene ( 2.588 -- 23.03 Mya ) Pliocene ( 2.588 -- 5.333 Mya ) Miocene ( 5.333 -- 23.03 Mya ) Paleogene ( 23.03 -- 66.0 Mya ) Oligocene ( 23.03 -- 33.9 Mya ) Eocene ( 33.9 -- 56.0 Mya ) Paleocene ( 56.0 -- 66.0 Mya ) Mesozoic era1 ( 66.0 -- 251.902 Mya ) Cretaceous ( 66.0 -- 145.0 Mya ) Late ( 66.0 -- 100.5 Mya ) Early ( 100.5 -- 145.0 Mya ) Jurassic ( 145.0 -- 201.3 Mya ) Late ( 145.0 -- 163.5 Mya ) Middle ( 163.5 -- 174.1 Mya ) Early ( 174.1 -- 201.3 Mya ) Triassic ( 201.3 -- 251.902 Mya ) Late ( 201.3 -- 237 Mya ) Middle ( 237 -- 247.2 Mya ) Early ( 247.2 -- 251.902 Mya ) Paleozoic era1 ( 251.902 -- 541.0 Mya ) Permian ( 251.902 -- 298.9 Mya ) Lopingian ( 251.902 -- 259.8 Mya ) Guadalupian ( 259.8 -- 272.3 Mya ) Cisuralian ( 272.3 -- 298.9 Mya ) Carboniferous ( 298.9 -- 358.9 Mya ) Pennsylvanian ( 298.9 -- 323.2 Mya ) Mississippian ( 323.2 -- 358.9 Mya ) Devonian ( 358.9 -- 419.2 Mya ) Late ( 358.9 -- 382.7 Mya ) Middle ( 382.7 -- 393.3 Mya ) Early ( 393.3 -- 419.2 Mya ) Silurian ( 419.2 -- 443.8 Mya ) Pridoli ( 419.2 -- 423.0 Mya ) Ludlow ( 423.0 -- 427.4 Mya ) Wenlock ( 427.4 -- 433.4 Mya ) Llandovery ( 433.4 -- 443.8 Mya ) Ordovician ( 443.8 -- 485.4 Mya ) Late ( 443.8 -- 458.4 Mya ) Middle ( 458.4 -- 470.0 Mya ) Early ( 470.0 -- 485.4 Mya ) Cambrian ( 485.4 -- 541.0 Mya ) Furongian ( 485.4 -- 497 Mya ) Series 3 ( 497 -- 509 Mya ) Series 2 ( 509 -- 521 Mya ) Terreneuvian ( 521 -- 541.0 Mya ) Proterozoic eon2 ( 541.0 Mya -- 2.5 Gya ) Neoproterozoic era ( 541.0 Mya -- 1 Gya ) Ediacaran ( 541.0 -- ~ 635 Mya ) Cryogenian ( ~ 635 -- ~ 720 Mya ) Tonian ( ~ 720 Mya -- 1 Gya ) Mesoproterozoic era ( 1 -- 1.6 Gya ) Stenian ( 1 -- 1.2 Gya ) Ectasian ( 1.2 -- 1.4 Gya ) Calymmian ( 1.4 -- 1.6 Gya ) Paleoproterozoic era ( 1.6 -- 2.5 Gya ) Statherian ( 1.6 -- 1.8 Gya ) Orosirian ( 1.8 -- 2.05 Gya ) Rhyacian ( 2.05 -- 2.3 Gya ) Siderian ( 2.3 -- 2.5 Gya ) Archean eon2 ( 2.5 -- 4 Gya ) Eras Neoarchean ( 2.5 -- 2.8 Gya ) Mesoarchean ( 2.8 -- 3.2 Gya ) Paleoarchean ( 3.2 -- 3.6 Gya ) Eoarchean ( 3.6 -- 4 Gya ) Hadean eon2 ( 4 -- 4.6 Gya ) kya = thousands years ago. Mya = millions years ago. Gya = billions years ago. 1 = Phanerozoic eon. 2 = Precambrian supereon. Source : ( 2017 / 02 ). International Commission on Stratigraphy. Retrieved 13 July 2015. Divisions of Geologic Time -- Major Chronostratigraphic and Geochronologic Units USGS Retrieved 10 March 2013. GND : 4163142 - 0 NDL : 00564856 Cambrian portal Retrieved from `` https://en.wikipedia.org/w/index.php?title=Cambrian&oldid=833228671 '' Categories : Cambrian Geological periods Paleozoic Hidden categories : Wikipedia articles incorporating a citation from the 1911 Encyclopaedia Britannica with Wikisource reference Webarchive template wayback links Use dmy dates from February 2013 Periods with timeline in infobox Articles containing Welsh - language text Articles containing German - language text All articles with specifically marked weasel - worded phrases Articles with specifically marked weasel - worded phrases from September 2016 All articles with unsourced statements Articles with unsourced statements from September 2016 Wikipedia articles needing clarification from September 2016 Wikipedia articles with GND identifiers Wikipedia articles with NDL identifiers Talk Contents About Wikipedia Afrikaans Alemannisch Asturianu বাংলা Bahasa Banjar Bân - lâm - gú Беларуская Беларуская ( тарашкевіца ) ‎ Български Brezhoneg Català Čeština Cymraeg Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 हिन्दी Hrvatski Bahasa Indonesia Íslenska Italiano עברית Basa Jawa ქართული Қазақша Кыргызча Latina Latviešu Lëtzebuergesch Lietuvių Limburgs Magyar Македонски مازِرونی Bahasa Melayu Mìng - dĕ̤ng - ngṳ̄ Nederlands 日本 語 Nordfriisk Norsk Norsk nynorsk Occitan Oʻzbekcha / ўзбекча پنجابی Piemontèis Polski Português Română Русский Саха тыла Scots Simple English Slovenčina Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் ไทย Türkçe Українська اردو Tiếng Việt Volapük 文言 Winaray Yorùbá 粵語 中文 72 more Edit links This page was last edited on 30 March 2018, at 10 : 50 ( UTC ). 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Question: where did the cambrian period get its name from
Answer: Cambria, the Latinised form of Cymru, the Welsh name for Wales, where Britain's Cambrian rocks are best exposed