| Ediacaran | ||
| Proterozoic: Neoproterozoic Era |
Ediacaran – Cambrian Geological Column |
The column on this page shows the temporal distribution of some important fossil finds from the Ediacaran (Vendian) and Terreneuvian. Start and end dates for the boundary and Cambrian stages are those published by the International Subcommission on Cambrian Stratigraphy; ages of the fossil beds mostly follow Martin et al. (2000).
The period from around the Ediacaran age Varanger and Marinoan Glaciations and the, now famous, Cambrian age "Burgess Shale" - type Lagerstätten is pivotal to understanding the fossil record, and to the broader interpretation of metazoan evolution. In the space of 100 million years – probably less – metazoan fossils make their first unqualified appearance and diversify to occupy a morphospace equalling if not exceeding that of today. During this time, also, we observe the appearance and possibly the demise of the enigmatic Ediacaran forms.
Chengjiang and Sirius Passet faunas are estimated at approximately 515 Ma (cf. the more widely known and considerably younger Burgess Shale fauna, which is Middle Cambrian, approximately 505 Ma).
Ediacaran assemblages from near Aus, in Namibia, are approximately 545 Ma.
Ediacaran assemblages from Zimnie Gory on the White Sea coast of Russia are approximately 555 Ma.
Previously, the oldest of the 'classic' Ediacaran assemblages were thought to be from Mistaken Point, Newfoundland, dated at approximately 565 Ma. Recent discoveries from the Drook Formation, much lower in the same series, suggest that metazoan communities in Newfoundland may have originated 20-30 My earlier.
Microfossils, including possible bilaterian metazoan embryos, are reported from the 580+ Ma Doushantuo Phosphate deposit.
One researcher has reported Ediacaran-type taxa from Sonora, Mexico, and proposed an age of 600 Ma. McMenamin 1996).
The earliest, widely accepted, metazoan fossils are circular impressions from the Twitya Formation in the Mackenzie Mountains, northwest Canada, approximately 610 Ma.
Further Reading
Wonderful Life – Stephen Jay Gould
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