Nimbia
From Wikipedia, the free encyclopedia
| Nimbia Fossil range: Cryogenian-Cambrian |
||||||
|---|---|---|---|---|---|---|
| Scientific classification | ||||||
|
Nimbia occlusa is a form of Ediacaran fossil shaped like a circular or oval disk, with a thick rim around the margin. Within the rim the fossil is usually flat, but may have a central nipple or dimple. These fossils were generally believed to be those of cnidarians, but they have since been reinterpreted as structures made by micriboal colonies (Grazhdankin, see Ediacaran biota for references and discussion.). They can reach up to 6 cm in diameter, with a centimeter-thick rim. Some fossils are distorted.
Nimbia occurs in numerous locations across a large range of time, which lends weight to theories that the fossil does not represent a single animal species. It occurs in the Twitya formation in the Mackenzie Mountains in Canada dated at 610 million years ago, near the end of the Marinoan glaciation. Aspidella also appears in this area. Morania and Beltina carbonaceous film fossils in the Twitya formation are not considered to be animals. Nimbia-like fossils have also been found in the Cambrian period, showing that it was a survivor of the mass extinction at the end of the Precambrian.
[edit] References
- Fedonkin MA. Novye Predstaviteli Dokembriyskikh Kishechnopolostnykh na Severe Russkoy Platformy (New Precambrian Coelenterata in the North of the Russian Platform). Paleontologicheskiy Zhurnal 2: 7-15. (1980)
