Nama assemblage
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The Nama assemblage was the last of the Ediacaran biotic assemblages, following the Avalon and White Sea assemblages, and spanning from c. 550 Ma to c. 539 Ma.[3] The assemblage was characterized by a faunal turnover, with the decline of the preexisting White Sea biota. The drop of diversity has been compared to the mass extinctions of the Phanerozoic. A second drop of diversity occurred at the Ediacaran–Cambrian boundary, concluding the Nama assemblages with the end-Ediacaran extinction.[4][5][6]
Etymology and definition
The Nama assemblage is named after the Nama Group in Namibia, preserving a Late Ediacaran record of soft-bodied fossils. While the earliest fossils in the Nama Group, known from the Tsaus Mountain environment, date back to before 550.5 Ma, they represent holdover taxa from the earlier Avalon and White Sea assemblages. A proposed definition of the Nama assemblage's lower boundary by Wood Template:Et al refers to the oldest appearance of Cloudina in the fossil record, placing the boundary at 550 Ma.[7]
References
- ^ Shen, Bing; Dong, Lin; Xiao, Shuhai; Kowalewski, Michal (4 January 2008). "The Avalon explosion: evolution of Ediacara morphospace". Science (New York, N.Y.). 319 (5859): 81–84. Bibcode:2008Sci...319...81S. doi:10.1126/science.1150279. ISSN 1095-9203. PMID 18174439.
- ^ 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.
- ^ Wood, Rachel; Bowyer, Fred T.; Alexander, Ruaridh; Yilales, Mariana; Uahengo, Collen-Issia; Kaputuaza, Kavevaza; Ndeunyema, Junias; Curtis, Andrew (September 2023). "New Ediacaran biota from the oldest Nama Group, Namibia (Tsaus Mountains), and re-definition of the Nama Assemblage". Geological Magazine. 160 (9): 1673–1686. Bibcode:2023GeoM..160.1673W. doi:10.1017/S0016756823000638. hdl:20.500.11820/bc8c23b0-d59c-4230-a45b-db854a8ad0f3. ISSN 0016-7568.
- ^ Bowyer, Fred T.; Uahengo, Collen-Issia; Kaputuaza, Kavevaza; Ndeunyema, Junias; Yilales, Mariana; Alexander, Ruaridh D.; Curtis, Andrew; Wood, Rachel A. (15 October 2023). "Constraining the onset and environmental setting of metazoan biomineralization: The Ediacaran Nama Group of the Tsaus Mountains, Namibia". Earth and Planetary Science Letters. 620: 118336. Bibcode:2023E&PSL.62018336B. doi:10.1016/j.epsl.2023.118336. ISSN 0012-821X.
{{cite journal}}: CS1 maint: article number as page number (link) - ^ 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.
{{cite journal}}: CS1 maint: article number as page number (link) - ^ 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.
- ^ Cite error: The named reference
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