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Nama Assemblage
The Nama assemblage was the last of the Ediacaran biotic Faunal assemblage, assemblages. Following the Avalon assemblage, Avalon and White Sea assemblages, it spanned from 550 megaannum, Ma to 539 Ma, coinciding with the Terminal Ediacaran biozone. 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. Etymology and definitions The Nama assemblage is named after the Nama Group from the Tsaus Mountains of Namibia, which preserves a Late Ediacaran record of soft-bodied fossils. The Biota (ecology), biota of the Namibian sites clusters with similar biotas found in the Southwestern United States, South China and British Columbia, leading to a Nama assemblage being first defined by Gehling in 2001. This def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloudina Carinata
The cloudinids, an early metazoan Family (biology), family containing the genus, genera ''Acuticocloudina'', ''Cloudina'' and ''Conotubus'', lived in the late Ediacaran Period (geology), period about 550 million years ago and became extinct at the base of the Cambrian. They formed millimetre-scale conical fossils consisting of calcareous cones nested within one another; the appearance of the organism itself remains unknown. The name ''Cloudina'' honors the 20th-century geologist and paleontologist Preston Cloud. Cloudinids comprise two genera: ''Cloudina'' itself is mineralized, whereas ''Conotubus'' is at best weakly mineralized, whilst sharing the same "funnel-in-funnel" construction. Cloudinids had a wide geographic range, reflected in the present distribution of localities in which their fossils are found, and are an abundant component of some deposits. They never appear in the same layers as soft-bodied Ediacaran biota, but the fact that some sequences contain cloudinids and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
