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| Cambrian | ||||||||||||||||||||||||||||||||||||||
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 A map of Earth as it appeared 510 million years ago during the Cambrian Period, Series 2 epoch | ||||||||||||||||||||||||||||||||||||||
| Chronology | ||||||||||||||||||||||||||||||||||||||
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| Etymology | ||||||||||||||||||||||||||||||||||||||
| Name formality | Formal | |||||||||||||||||||||||||||||||||||||
| Usage information | ||||||||||||||||||||||||||||||||||||||
| Celestial body | Earth | |||||||||||||||||||||||||||||||||||||
| Regional usage | Global (ICS) | |||||||||||||||||||||||||||||||||||||
| Time scale(s) used | ICS Time Scale | |||||||||||||||||||||||||||||||||||||
| Definition | ||||||||||||||||||||||||||||||||||||||
| Chronological unit | Period | |||||||||||||||||||||||||||||||||||||
| Stratigraphic unit | System | |||||||||||||||||||||||||||||||||||||
| First proposed by | Adam Sedgwick, 1835 | |||||||||||||||||||||||||||||||||||||
| Time span formality | Formal | |||||||||||||||||||||||||||||||||||||
| Lower boundary definition | Appearance of the Ichnofossil Treptichnus pedum | |||||||||||||||||||||||||||||||||||||
| Lower boundary GSSP | Fortune Head section, Newfoundland, Canada 47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W | |||||||||||||||||||||||||||||||||||||
| Lower GSSP ratified | 1992[2] | |||||||||||||||||||||||||||||||||||||
| Upper boundary definition | FAD of the Conodont Iapetognathus fluctivagus. | |||||||||||||||||||||||||||||||||||||
| Upper boundary GSSP | Greenpoint section, Green Point, Newfoundland, Canada 49°40′58″N 57°57′55″W / 49.6829°N 57.9653°W | |||||||||||||||||||||||||||||||||||||
| Upper GSSP ratified | 2000[3] | |||||||||||||||||||||||||||||||||||||
| Atmospheric and climatic data | ||||||||||||||||||||||||||||||||||||||
| Sea level above present day | Rising steadily from 4 m to 90 m[4] | |||||||||||||||||||||||||||||||||||||
| Part of a series on |
| The Cambrian explosion |
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The Cambrian ( /ˈkæmbri.ən, ˈkeɪm-/ KAM-bree-ən, KAYM-) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon.[5] The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma.[1]
Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean.[6] The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures.[7] Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean.[6]
The Cambrian marked a profound change in life on Earth; prior to the Period, the majority of living organisms were small, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it was not until the Cambrian that fossil diversity seems to rapidly increase, known as the Cambrian explosion, produced the first representatives of most modern animal phyla.[8] The Period is also unique in its unusually high proportion of lagerstätte deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells.[9]
- ^ a b "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. December 2024. Retrieved 2 January 2025.
- ^ Brasier, Martin; Cowie, John; Taylor, Michael (March–June 1994). "Decision on the Precambrian-Cambrian boundary stratotype" (PDF). Episodes. 17 (1–2): 3–8. doi:10.18814/epiiugs/1994/v17i1.2/002. Archived (PDF) from the original on 9 October 2022.
- ^ Cooper, Roger; Nowlan, Godfrey; Williams, S. H. (March 2001). "Global Stratotype Section and Point for base of the Ordovician System" (PDF). Episodes. 24 (1): 19–28. doi:10.18814/epiiugs/2001/v24i1/005. Archived (PDF) from the original on 9 October 2022. Retrieved 6 December 2020.
- ^ Haq, B. U.; Schutter, SR (2008). "A Chronology of Paleozoic Sea-Level Changes". Science. 322 (5898): 64–8. Bibcode:2008Sci...322...64H. doi:10.1126/science.1161648. PMID 18832639. S2CID 206514545.
- ^ Howe 1911, p. 86.
- ^ a b Cite error: The named reference
Torsvik-2017was invoked but never defined (see the help page). - ^ Cite error: The named reference
Myrow-2024was invoked but never defined (see the help page). - ^ Butterfield, N. J. (2007). "Macroevolution and macroecology through deep time". Palaeontology. 50 (1): 41–55. Bibcode:2007Palgy..50...41B. doi:10.1111/j.1475-4983.2006.00613.x.
- ^ 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.