Ediacaran
Ediacaran | |
---|---|
Marinoan glaciation |
← | Palaeopascichnids |
← | Lantian biota appears |
Major Glacial period |
Vertical axis scale:
- Worldwide distinct cap carbonates.
- Beginning of a distinctive pattern of secular changes in carbon isotopes.
(16 times pre-industrial)
(3.5 °C above pre-industrial)
The Ediacaran (
The Ediacaran Period is named after the
The Ediacaran marks the first widespread appearance of complex
The supercontinent Pannotia formed and broke apart by the end of the period. The Ediacaran also witnessed several glaciation events, such as the Gaskiers and Baykonurian glaciations. The Shuram excursion also occurred during this period, but its glacial origin is unlikely.
Ediacaran vs. Vendian
The Ediacaran Period overlaps but is shorter than the Vendian Period (650 to 543 million years ago), a name that was earlier, in 1952, proposed by Russian geologist and
Paleontological substantiation of this boundary was worked out separately for the
The Vendian in its type area consists of large subdivisions such as Laplandian,
The Redkino, Kotlin and Rovno regional stages have been substantiated in the type area of the Vendian on the basis of the abundant organic-walled
The lower boundary of the Vendian could have a
Upper and lower boundaries

The Ediacaran Period (c. 635–538.8 Mya) represents the time from the end of global
Although the Ediacaran Period does contain soft-bodied fossils, it is unusual in comparison to later periods because its beginning is not defined by a change in the fossil record. Rather, the beginning is defined at the base of a chemically distinctive carbonate layer that is referred to as a "cap carbonate", because it caps glacial deposits.
This bed is characterized by an unusual depletion of 13
The
Nevertheless, the definitions of the lower and upper boundaries of the Ediacaran on the basis of chemostratigraphy and
Cap carbonates generally have a restricted geographic distribution (due to specific conditions of their precipitation)[vague] and usually siliciclastic sediments laterally replace the cap carbonates in a rather short distance but cap carbonates do not occur above every tillite elsewhere[clarification needed] in the world.
The C-isotope chemostratigraphic characteristics obtained for contemporaneous cap carbonates in different parts of the world may be variable in a wide range owing to different degrees of secondary alteration of carbonates, dissimilar criteria used for selection of the least altered samples, and, as far as the C-isotope data are concerned, due to primary lateral variations of δ l3Ccarb in the upper layer of the ocean.[16][19]
Furthermore, Oman presents in its stratigraphic record a large negative carbon isotope excursion, within the Shuram[20] Formation that is clearly away from any glacial evidence[21] strongly questioning systematic association of negative δ l3Ccarb excursion and glacial events.[22] Also, the Shuram excursion is prolonged and is estimated to last for ~9.0 Myrs.[23]
As to the Treptichnus pedum, a reference ichnofossil for the lower boundary of the Cambrian, its usage for the stratigraphic detection of this boundary is always risky, because of the occurrence of very similar trace fossils belonging to the Treptichnids group well below the level of T. pedum in Namibia, Spain and Newfoundland, and possibly, in the western United States. The stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, and probably in Spain.[16][24]
Subdivisions

The Ediacaran Period is not yet formally subdivided, but a proposed scheme[26] recognises an Upper Ediacaran whose base corresponds with the Gaskiers glaciation, a Terminal Ediacaran Stage starting around 550 million years ago, a preceding stage beginning around 575 Ma with the earliest widespread Ediacaran biota fossils; two proposed schemes differ on whether the lower strata should be divided into an Early and Middle Ediacaran or not, because it is not clear whether the Shuram excursion (which would divide the Early and Middle) is a separate event from the Gaskiers, or whether the two events are correlated.
Absolute dating
The dating of the rock type section of the Ediacaran Period in South Australia has proven uncertain due to lack of overlying igneous material. Therefore, the age range of 635 to 538.8 million years is based on correlations to other countries where dating has been possible. The base age of approximately 635 million years is based on U–Pb (uranium–lead) and Re–Os (rhenium–osmium) dating from Africa, China, North America, and Tasmania.[27][28][29][30][31]
Biota
The fossil record from the Ediacaran Period is sparse, as more easily fossilized hard-shelled animals had yet to evolve. The Ediacaran biota include the oldest definite
Most members of the Ediacaran biota bear little resemblance to modern lifeforms, and their
Four different biotic intervals are known in the Ediacaran, each being characterised by the prominence of a unique ecology and faunal assemblage. The first spanned from 635 to around 575 Ma and was dominated by acritarchs known as large ornamented Ediacaran microfossils.[39] The second spanned from around 575 to 560 Ma and was characterised by the Avalon biota. The third spanned from 560 to 550 Ma; its biota has been dubbed the White Sea biota due to many fossils from this time being found along the coasts of the White Sea. The fourth lasted from 550 to 539 Ma and is known as the interval of the Nama biotic assemblage.[40]
There is evidence for a mass extinction during this period from early animals changing the environment,[41] dating to the same time as the transition between the White Sea and the Nama-type biotas.[42][43] Alternatively, this mass extinction has also been theorised to have been the result of an anoxic event.[40]
Astronomical factors
The relative proximity of the Moon at this time meant that tides were stronger and more rapid than they are now. The day was 21.9 ± 0.4 hours, and there were 13.1 ± 0.1 synodic months/year and 400 ± 7 solar days/year.[44]
Documentaries
A few English language documentaries have featured the Ediacaran Period and biota:
- ABC Science; Part 1 of 4).[45]
- The Geological History of Canada, as part of The Nature of Things series, CBC-SRC; 2011; Eastern Canada.
- The first episode of a BBC documentary titled Life on Earth, with David Attenborough as narrator.
- Another documentary narrated by David Attenborough titled First Life featuring Charnia, Dickinsonia, Spriggina, Funisia, and Kimberella animated in CGI.
See also
- List of fossil sites (with link directory)
- Avalon explosion
- End-Ediacaran extinction
References
- . Retrieved 6 December 2020.
- ^ Brasier, Martin; Cowie, John; Taylor, Michael. "Decision on the Precambrian-Cambrian boundary stratotype" (PDF). Episodes. 17. Retrieved 6 December 2020.
- ^ "Ediacaran". Dictionary.com Unabridged (Online). n.d.
- ^ "Stratigraphic Chart 2022" (PDF). International Stratigraphic Commission. February 2022. Retrieved 20 April 2022.
- ^ Sprigg, Reg. C. (1947). "Early Cambrian (?) jellyfishes from the Flinders Ranges, South Australia". Transactions of the Royal Society of South Australia. 71 (2): 212–224.
- ^ a b 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.
- S2CID 32763298.
- doi:10.1080/00241160500409223. Archived from the original(PDF) on 21 February 2007.
- ^ "Geological time gets a new period: Geologists have added a new period to their official calendar of Earth's history—the first in 120 years". London: BBC. 17 May 2004. Accessed 27 December 2010.
- ^ South Australian Museum Newsletter April 2005 Archived 17 February 2011 at the Wayback Machine Accessed 9 August 2010.
- PMID 11538690. Archived from the originalon 22 May 2011. Retrieved 19 July 2008.
- ^ B. M. Sokolov (1952). "On the age of the old sedimentary cover of the Russian Platform". Izvestiya Akademii Nauk SSSR, Seriya Eologicheskaya. 5: 21–31.
- ^ a b c Sokolov, B.S. (1997). "Essays on the Advent of the Vendian System." 153 pp. KMK Scientific Press, Moscow. (in Russian)
- ^ Sokolov B. S. (1965) "Abstracts of All-Union Symposium on Paleontology of the Precambrian and Early Cambrian." Nauka, Novosibirsk.
- ^ Rozanov, A.Y.; Missarzhevskij, V.V.; Volkova, N.A.; Voronova, L.G.; Krylov, I.N.; Keller, B.M.; Korolyuk, I.K.; Lendzion, K.; Michniak, R.; Pykhova, N.G. & Sidorov, A.D. (1969). "The Tommotian Stage and the problem of the lower boundary of the Cambrian". Trudy Geologičeskogo Instituta AN SSSR. 206: 1–380.
- ^ a b c d e M. A. Fedonkin; B. S. Sokolov; M. A. Semikhatov; N. M. Chumakov (2007). "Vendian versus Ediacaran: priorities, contents, prospectives". Archived from the original on 4 October 2011. In: "The Rise and Fall of the Vendian (Ediacaran) Biota" (PDF). Origin of the Modern Biosphere. Transactions of the International Conference on the IGCP Project 493n Moscow: GEOS. 20–31 August 2007. Archived from the original (PDF) on 22 November 2012. (82mb)
- S2CID 128966206.
- ^ Comments By B. S. Sokolov, M. A. Semikhatov, And M. A. Fedonkin. (2004) Appendix 2 in: "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. pp. 32–34
- doi:10.1130/G24968A.1. Archived from the original(PDF) on 7 May 2020. Retrieved 5 May 2007.
- .
- S2CID 140710102. Archived from the originalon 5 January 2013.
- S2CID 128910191. Archived from the originalon 5 January 2013.
- .
- ^ A. Ragozina, D. Dorjnamjaa, A. Krayushkin, E. Serezhnikova (2008). "Treptichnus pedum and the Vendian-Cambrian boundary Archived 4 October 2011 at the Wayback Machine". 33 Intern. Geol. Congr. August 6–14, 2008, Oslo, Norway. Abstracts. Section HPF 07 Rise and fall of the Ediacaran (Vendian) biota. P. 183.
- ^ B. Laumonier et al., Notice explicative de la feuille Prats-de-Mollo-La-preste (1099) à 1/50 000, BRGM Éditions, Orléans, 2015, pages 22-23 (bC1 - « ...niveau de marbres calcaires et dolomitiques M1...(dans les) hautes vallées de la Ribérole et de la Carança M1 est formé de 2 ou 3 niveaux décamétriques très continus. », ficheinfoterre.brgm.fr.
- .
- ISSN 1943-2682.
- S2CID 218815302.
- ISSN 0091-7613.
- ISBN 978-0-444-59425-9, retrieved 2 April 2022
- ISSN 1943-2682.
- ISBN 9780801886799. Retrieved 7 August 2022 – via Google Books.
- PMID 35879540.
- ^ Amos, Jonathan (25 July 2022). "Ancient fossil is earliest known animal predator". BBC News. Retrieved 7 August 2022.
- PMID 18952316. Retrieved 10 November 2022.
- S2CID 59945361. Retrieved 10 November 2022.
- ISSN 1068-7971.
- PMID 32817471.
- PMID 19366668.
- ^ PMID 36343248. Retrieved 24 November 2023.
- ISSN 1342-937X. Retrieved 24 November 2023.
- PMID 26336166.
- ^ Evidence that Earth's first mass extinction was caused by critters not catastrophe, ScienceDaily
- S2CID 51948507.
- ^ Celebrating 50 years of ABC Science Retrieved 18 March 2023.
External links
- "Geological time gets a new period: Geologists have added a new period to their official calendar of Earth's history—the first in 120 years". London: BBC. 17 May 2004.
- "Ediacaran Period". GeoWhen Database. Archived from the original on 16 October 2019. Retrieved 5 January 2006.
- Introduction to the Vendian Period
- transcript – Catalyst (Australian Broadcasting Corporation)
- Mistaken Point Fauna: The Discovery
- Earth's oldest animal ecosystem held in fossils at Nilpena Station in SA outback ABC News, 5 August 2013. Accessed 6 August 2013.
- Australia: The Time Traveller's Guide (2012) at IMDb
- In Our Time – Ediacara Biota, BBC Radio, 9 July 2009. Accessed 1 February 2025.