White Sea assemblage

White Sea Assemblage
~560 – ~550 Ma [1] PreꞒ Ꞓ O S D C P T J K Pg N
Kimberella fossil from the Ustʹ Pinega Formation near the White Sea in Russia.
Chronology
−575 — – −570 — – −565 — – −560 — – −555 — – −550 — – −545 — – −540 — – N e o p r o t e r o z o i c P Z Ediacaran Cambrian         Avalon Assemblage White Sea Assemblage Nama Assemblage ← Second pulse of the end-Ediacaran extinction ← ~Baykonurian glaciation ← First pulse of the end-Ediacaran extinction ← Avalon Explosion ← Shuram excursion reaches its peak   Major Glacial period   Shuram excursion [2] Stratigraphic scale of the ICS subdivisions and Ediacaran biotic assmblages Vertical axis scale: millions of years ago

The White Sea assemblage, also known as the Ediacaran assemblage, was the second of the three Late Ediacaran biotic assemblages of fossils, following the Avalon assemblage and preceding the Nama assemblage.

Overview

This assemblage is named after Russia's White Sea or Australia's Ediacara Hills, and is marked by much higher diversity than the Avalon or Nama assemblages. ^[3] It spanned from c. 560 Ma to c. 550 Ma. Showing an increase in genus diversity from the Avalon assemblage, it concluded with a faunal turnover often characterized as the first pulse of the end-Ediacaran extinction, with only 20% of White Sea taxa found in the later Nama assemblage despite similar taphonomic processes. ^{[4] [5]}

Most fossils are preserved as imprints in microbial beds, ^[6] but a few are preserved within sandy units. ^[7]

Australia

In Australia, they are typically found in red gypsiferous and calcareous paleosols formed on loess and flood deposits in an arid cool temperate paleoclimate. ^[8] There are many fossil beds of this era in the Ediacara Hills of South Australia, west of the Flinders Ranges.

In the mid-1980s, rich fossil beds were discovered on a cattle station called Nilpena Station, that later became the focus of much research as well as an application for World Heritage listing to help protect the site. ^{[9] [10]} The entire property has now been sold to the state government to become part of the Nilpena Ediacara National Park. ^[11] Since the early 2000s, around 40 fossil surfaces preserving organisms from the White Sea Assemblage have been excavated from the Ediacara Member of the Rawnsley Quartzite in the Ediacara Hills. The fossil bed known as 1T-F has the highest diversity of Ediacaran fossils found so far, which also show significant ecological complexity. The bed includes more than 400 fossils across 16 genera. ^[12]

References

1. Shen, Bing; Dong, Lin; Xiao, Shuhai; Kowalewski, Michal (4 January 2008). "The Avalon explosion: evolution of Ediacara morphospace". Science. 319 (5859): 81–84. Bibcode:2008Sci...319...81S. doi:10.1126/science.1150279. ISSN   1095-9203. PMID   18174439.
2. Shi, Wei; Li, Chao; Luo, Genming; Huang, Junhua; Algeo, Thomas J.; Jin, Chengsheng; Zhang, Zihu; Cheng, Meng (24 January 2018). "Sulfur isotope evidence for transient marine-shelf oxidation during the Ediacaran Shuram Excursion". Geology. 46 (3): 267–270. doi:10.1130/G39663.1.
3. Evans, Scott D.; Tu, Chenyi; Rizzo, Adriana; Surprenant, Rachel L.; Boan, Phillip C.; McCandless, Heather; Marshall, Nathan; Xiao, Shuhai; Droser, Mary L. (15 November 2022). "Environmental drivers of the first major animal extinction across the Ediacaran White Sea-Nama transition". Proceedings of the National Academy of Sciences. 119 (46) e2207475119. Bibcode:2022PNAS..11907475E. doi: 10.1073/pnas.2207475119 . ISSN   0027-8424. PMC   9674242 . PMID   36343248.
4. Evans, Scott D.; Tu, Chenyi; Rizzo, Adriana; Surprenant, Rachel L.; Boan, Phillip C.; McCandless, Heather; Marshall, Nathan; Xiao, Shuhai; Droser, Mary L. (15 November 2022). "Environmental drivers of the first major animal extinction across the Ediacaran White Sea-Nama transition". Proceedings of the National Academy of Sciences. 119 (46) e2207475119. Bibcode:2022PNAS..11907475E. doi: 10.1073/pnas.2207475119 . ISSN   0027-8424. PMC   9674242 . PMID   36343248.
5. Bottjer, David J.; Clapham, Matthew E. (2006). Xiao, Shuhai; Kaufman, Alan J. (eds.). Evolutionary Paleoecology of Ediacaran Benthic Marine Animals. Dordrecht: Springer Netherlands. pp. 91–114. doi:10.1007/1-4020-5202-2_4. ISBN   978-1-4020-5202-6.
6. Retallack G. J. (2012). Criteria for distinguishing microbial mats and earths (Report). Special Paper. Vol. 101. Tulsa: Society of Economic Paleontologists and Mineralogists. pp. 136–152.
7. Grazhdankin, Dima (2004). "Patterns of distribution in the Ediacaran biotas: facies versus biogeography and evolution" (PDF). Paleobiology . 30 (2): 203–221. Bibcode:2004Pbio...30..203G. doi:10.1666/0094-8373(2004)030<0203:PODITE>2.0.CO;2. S2CID   129376371. Archived (PDF) from the original on 26 July 2011. Retrieved 10 April 2007. (Source of data for Timeline synthesis, p. 218. Further citations available in caption to Fig. 8.)
8. Retallack, G. J. (2013). "Ediacaran life on land". Nature. 493 (7430): 89–92. Bibcode:2013Natur.493...89R. doi:10.1038/nature11777. PMID   23235827. S2CID   205232092.
9. Gage, Nicola. Flinders Ranges fossils documented as part of World Heritage listing bid ABC News, 13 February 2017. Retrieved 24 March 2020.
10. Rare fossil sites in the Flinders Ranges one step closer to gaining World Heritage status ABC News, 2 May 2021. Retrieved 3 May 2021.
11. Staight, Kerry (9 August 2025). "Future of world-significant fossil site secured with Nilpena cattle station sale". ABC News .
12. Weyland, W. C.; Droser, M. L. (17 February 2025). "The Ediacaran Aquarium: insights from the Nilpena Ediacara National Park 1T-F Marine Ecosystem (Ediacara Member, Rawnsley Quartzite)". Australian Journal of Earth Sciences . 72 (2): 151–168. doi: 10.1080/08120099.2025.2462660 . ISSN   0812-0099.