Cambrian Period ( /ˈkæmbriən/ or /ˈkeɪmbriən/) was the first
geological period of the
Paleozoic Era, and of the Phanerozoic
Cambrian lasted 55.6 million years from the end of
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 Latin name of 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
surpasses that of some later periods.
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
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 life forms 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
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. 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.
1.2 Dating the Cambrian
5 Oceanic life
8 See also
10 Further reading
11 External links
Further information: Stratigraphy of the Cambrian
Despite the long recognition of its distinction from younger
Ordovician rocks and older
Precambrian rocks, it was not until 1994
Cambrian system/period was internationally ratified. The base
Cambrian lies atop a complex assemblage of trace fossils known
Treptichnus pedum assemblage.
The use of Treptichnus pedum, a reference ichnofossil to mark the
lower boundary of the Cambrian, is difficult since 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
Cambrian Period followed the
Ediacaran Period and was followed by
Ordovician Period. The
Cambrian is divided into four epochs
(series) and ten ages (stages). Currently only three series and six
stages are named and have a GSSP (an internationally agreed-upon
stratigraphic reference point).
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 series (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 series 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:
Dolgellian (Trempealeauan, Fengshanian)
Ffestiniogian (Franconian, Changshanian)
Cambrian Series 2
*Most Russian paleontologists define the lower boundary of the
Cambrian at the base of the Tommotian Stage, characterized by
diversification and global distribution of organisms with mineral
skeletons and the appearance of the first Archaeocyath
Dating the Cambrian
Archeocyathids from the
Poleta formation in the
Death Valley area
International Commission on Stratigraphy list the
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
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
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
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 sections, ranging from 544 or 542 Ma,
are more suitable.
Plate reconstructions suggest a global supercontinent, Pannotia, was
in the process of breaking up early in the
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
Gondwana appears to have occurred in the Early
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.
Baltoscandia a Lower
Cambrian transgression transformed large
swathes of the
Sub-Cambrian peneplain into an epicontinental
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
Although there were a variety of macroscopic marine
plants[which?] 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.
Life timelineThis box:
viewtalkedit-4500 —–-4000 —–-3500 —–-3000 —–-2500 —–-2000 —–-1500 —–-1000 —–-500 —–0 —waterSingle-celled
lifephotosynthesisEukaryotesMulticellular lifeArthropods and
(−4540)←Earliest water←Earliest life←Earliest
AgesAxis scale: million years
(See also: Human timeline, and Nature timeline.)
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
(CaCO3), which fossilized far more easily than the fragile chitinous
exoskeletons of other arthropods, leaving numerous preserved
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.[clarification needed] 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
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
While the early
Cambrian showed such diversification that it has been
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.
Cambrian organisms ventured onto land, producing the trace
Protichnites and Climactichnites. Fossil evidence suggests
that euthycarcinoids, an extinct group of arthropods, produced at
least some of the Protichnites. Fossils of the
Climactichnites have not been found; however, fossil
trackways and resting traces suggest a large, slug-like
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.
The United States
Federal Geographic Data Committee
Federal Geographic Data Committee uses a "barred
capital C" ⟨Ꞓ⟩ character to represent the Cambrian
Unicode character is .mw-parser-output .monospaced
font-family:monospace,monospace U+A792 Ꞓ .mw-parser-output
.smallcaps font-variant:small-caps LATIN CAPITAL LETTER C WITH
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
Hallucigenia is maybe an early ancestor of the Velvet worms.
Reconstructions of H. sparsa, H. hongmeia, and H. fortis
Size comparison of different
Part of a series onThe
Small shelly fauna
Cambrian substrate revolution
Stem and crown groups
Ordovician extinction event – circa 488 mya
Dresbachian extinction event—circa 502 mya
End Botomian extinction event—circa 517 mya
List of fossil sites
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
vteModes of preservation in the CambrianExceptional
Bitter Springs type
Burgess Shale type
Trilobite Bed type
Small shelly fossils
Phanerozoic Carbon Dioxide.png
^ Image:All palaeotemps.png
^ Haq, B. U.; Schutter, SR (2008). "A Chronology of Paleozoic
Sea-Level Changes". Science. 322 (5898): 64–8.
PMID 18832639..mw-parser-output cite.citation font-style:inherit
.mw-parser-output .citation q quotes:"""""""'""'" .mw-parser-output
.citation .cs1-lock-free a
.1em center .mw-parser-output .citation .cs1-lock-limited
a,.mw-parser-output .citation .cs1-lock-registration a
.1em center .mw-parser-output .citation .cs1-lock-subscription a
.1em center .mw-parser-output .cs1-subscription,.mw-parser-output
.cs1-registration color:#555 .mw-parser-output .cs1-subscription
span,.mw-parser-output .cs1-registration span border-bottom:1px
dotted;cursor:help .mw-parser-output .cs1-ws-icon a
.1em center .mw-parser-output code.cs1-code
.mw-parser-output .cs1-hidden-error display:none;font-size:100%
.mw-parser-output .cs1-visible-error font-size:100% .mw-parser-output
.cs1-registration,.mw-parser-output .cs1-format font-size:95%
.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left
padding-left:0.2em .mw-parser-output .cs1-kern-right,.mw-parser-output
^ a b Chisholm, Hugh, ed. (1911). "
Cambrian System" .
Encyclopædia Britannica (11th ed.). Cambridge University Press.
^ "Stratigraphic Chart 2012" (PDF). International Stratigraphic
Commission. Archived from the original (PDF) on 20 April 2013.
Retrieved 9 November 2012.
^ Sedgwick and R. I. Murchison (1835) "On the
Silurian and Cambrian
systems, exhibiting the order in which the older sedimentary strata
succeed each other in England and Wales," Notices and Abstracts of
Communications to the British Association for the Advancement of
Science at the Dublin meeting, August 1835, pp. 59-61, in: Report of
the Fifth Meeting of the British Association for the Advancement of
Science; held in Dublin in 1835 (1836). From p. 60: "Professor
Sedgwick then described in descending order the groups of slate rocks,
as they are seen in
Wales and Cumberland. To the highest he gave the
name of Upper
Cambrian group. ... To the next inferior group he gave
the name of Middle Cambrian. ... The Lower
Cambrian group occupies the
S.W. coast of Cærnarvonshire,"
^ Sedgwick, A. (1852). "On the classification and nomenclature of the
Paleozoic rocks of England and Wales". Q. J. Geol. Soc. Lond. 8
(1–2): 136–138. doi:10.1144/GSL.JGS.1852.008.01-02.20.
^ Chambers 21st Century Dictionary.
Chambers Dictionary (Revised ed.).
New Dehli: Allied Publishers. 2008. p. 203.
^ Orr, P. J.; Benton, M. J.; Briggs, D. E. G. (2003). "Post-Cambrian
closure of the deep-water slope-basin taphonomic window". Geology. 31
(9): 769–772. Bibcode:2003Geo....31..769O. doi:10.1130/G19193.1.
^ Butterfield, N. J. (2007). "Macroevolution and macroecology through
deep time". Palaeontology. 50 (1): 41–55.
^ a b Schieber, 2007, pp. 53–71.
^ Seilacher, A.; Hagadorn, J.W. (2010). "Early Molluscan evolution:
evidence from the trace fossil record" (PDF). PALAIOS (Submitted
manuscript). 25 (9): 565–575. Bibcode:2010Palai..25..565S.
^ A. Knoll, M. Walter, G. Narbonne, and N. Christie-Blick (2004) "The
Ediacaran Period: A New Addition to the Geologic Time Scale."
Submitted on Behalf of the Terminal
Proterozoic Subcommission of the
International Commission on Stratigraphy.
^ M.A. Fedonkin, B.S. Sokolov, M.A. Semikhatov, N.M.Chumakov (2007).
"Vendian versus Ediacaran: priorities, contents, prospectives.
Archived 4 October 2011 at the Wayback Machine" In: edited by M. A.
Semikhatov "The Rise and Fall of the Vendian (Ediacaran) Biota. Origin
of the Modern Biosphere. Transactions of the International Conference
on the IGCP Project 493, August 20–31, 2007, Moscow." Moscow: GEOS.
^ A. Ragozina, D. Dorjnamjaa, A. Krayushkin, E. Serezhnikova (2008).
Treptichnus pedum and the Vendian-
Cambrian boundary". 33 Intern.
Geol. Congr. 6–14 August 2008, Oslo, Norway. Abstracts. Section HPF
07 Rise and fall of the
Ediacaran (Vendian) biota. P. 183.
^ A.Yu. Rozanov; V.V. Khomentovsky; Yu.Ya. Shabanov; G.A. Karlova;
A.I. Varlamov; V.A. Luchinina; T.V. Pegel’; Yu.E. Demidenko; P.Yu.
Parkhaev; I.V. Korovnikov; N.A. Skorlotova (2008). "To the problem of
stage subdivision of the Lower Cambrian". Stratigraphy and Geological
Correlation. 16 (1): 1–19. Bibcode:2008SGC....16....1R.
^ B. S. Sokolov; M. A. Fedonkin (1984). "The Vendian as the Terminal
System of the Precambrian" (PDF). Episodes. 7 (1): 12–20. Archived
from the original (PDF) on 25 March 2009.
^ V. V. Khomentovskii; G. A. Karlova (2005). "The Tommotian Stage Base
Cambrian Lower Boundary in Siberia". Stratigraphy and
Geological Correlation. 13 (1): 21–34.
^ a b c d e Geyer, Gerd; Landing, Ed (2016). "The
Phanerozoic and Ediacaran–
Cambrian boundaries: A
historical approach to a dilemma". Geological Society, London, Special
Publications. 448 (1): 311–349. Bibcode:2017GSLSP.448..311G.
^ Landing, Ed; Geyer, Gerd; Brasier, Martin D.; Bowring, Samuel A.
Cambrian Evolutionary Radiation: Context, correlation, and
chronostratigraphy—Overcoming deficiencies of the first appearance
datum (FAD) concept". Earth-Science Reviews. 123: 133–172.
^ Gradstein, F.M.; Ogg, J.G.; Smith, A.G.; et al. (2004). A Geologic
Time Scale 2004. Cambridge University Press.
^ 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:
^ 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):
^ a b Mckerrow, W. S.; Scotese, C. R.; Brasier, M. D. (1992). "Early
Cambrian continental reconstructions". Journal of the Geological
Society. 149 (4): 599–606. Bibcode:1992JGSoc.149..599M.
^ Mitchell, R. N.; Evans, D. A. D.; Kilian, T. M. (2010). "Rapid Early
Cambrian rotation of Gondwana". Geology. 38 (8): 755.
^ Smith, A.G. (2008). "
Neoproterozoic time scales and stratigraphy".
Geol. Soc. (
^ 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 (1–2): 9–33. doi:10.1016/j.palaeo.2009.02.010.
^ Nielsen, Arne Thorshøj; Schovsbo, Niels Hemmingsen (2011). "The
Cambrian of Scandinavia: Depositional environment, sequence
stratigraphy and palaeogeography". Earth-Science Reviews. 107 (3–4):
^ Retallack, G.J. (2008). "
Cambrian palaeosols and landscapes of South
Australia". Alcheringa. 55 (8): 1083–1106.
^ University of Oregon (22 July 2013). "Greening of the Earth pushed
way back in time". Phys.org.
^ Paselk, Richard (28 October 2012). "Cambrian". Natural History
Museum. Humboldt State University.
^ Ward, Peter (2006). 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.
^ Perkins, Sid (23 September 2013). "As the worms churn".
^ Taylor, P.D.; Berning, B.; Wilson, M.A. (2013). "Reinterpretation of
Cambrian 'bryozoan' Pywackia as an octocoral". Journal of
Paleontology. 87 (6): 984–990. doi:10.1666/13-029.
^ 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.
^ Nanglu, Karma; Caron, Jean-Bernard; Conway Morris, Simon; Cameron,
Christopher B. (2016). "
Cambrian suspension-feeding tubicolous
hemichordates". BMC Biology. 14: 56. doi:10.1186/s12915-016-0271-4.
PMC 4936055. PMID 27383414.
^ The Ordovician: Life's second big bang
^ Marshall, Michael. "
Oxygen crash led to
Cambrian mass extinction".
^ Collette & Hagadorn, 2010.
^ Collette, Gass & Hagadorn, 2012
^ Yochelson & Fedonkin, 1993.
^ Getty & Hagadorn, 2008.
^ a b Munnecke, A.; Calner, M.; Harper, D. A. T.; Servais, T. (2010).
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.
^ 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.
^ Priest, Lorna A.; Iancu, Laurentiu; Everson, Michael (October 2010).
"Proposal to Encode C WITH BAR" (PDF). Retrieved 6 April 2011.
Unicode Character 'LATIN CAPITAL LETTER C WITH BAR' (U+A792).
fileformat.info. Accessed 15 Jun 2015
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).
Namacalathus at the Precambrian-Cambrian
boundary in Oman". Geology. 31 (5): 431–434.
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.
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)
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 (1–2): 214–225.
Peng, S.; Babcock, L.E.; Cooper, R.A. (2012). "The
(PDF). The Geologic Time Scale.
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". Smithsonian
Contributions to Paleobiology. 74 (74): 1–74.
Wikimedia Commons has media related to Cambrian.
Cambrian period on In Our Time at the BBC
Biostratigraphy – includes information on
Dr. Sam Gon's trilobite pages (contains numerous
Report on the web on Amthor and others from Geology vol. 31
Life on the Mats
Chronostratigraphy scale v.2018/08 Cambrian
vteGeological history of EarthCenozoic
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 era(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 era(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)
Miaolingian (497–509 Mya)
Series 2 (509–521 Mya)
Terreneuvian (521–541.0 Mya)
Proterozoic eon(541.0 Mya–2.5 Gya)
Neoproterozoic era (541.0 Mya–1
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 eon (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 eon (4–4.6 Gya) kya = thousands years ago. Mya =
millions years ago. Gya = billions years ago.
See also: Geologic time scale, Geology Portal