Diskagma buttonii
| Diskagma buttonii | ||||||||||
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Holotype of the fossil Diskagma buttonii from 2.2 billion old paleosoils in South Africa |
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| Temporal occurrence | ||||||||||
| Paleoproterozoic | ||||||||||
| 2200 million years | ||||||||||
| Locations | ||||||||||
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| Systematics | ||||||||||
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| Scientific name of the genus | ||||||||||
| Discagma | ||||||||||
| Retallack et al., 2013 | ||||||||||
| Scientific name of the species | ||||||||||
| Diskagma buttonii | ||||||||||
| Retallack et al., 2013 | ||||||||||
Diskagma buttonii was a small, urn-shaped creature whose fossil remains, which are very common locally, were found on a paleo soil from the Paleoproterozoic in South Africa . It was found in the 2.2 billion year old Hekpoort Formation near Waterval Onder in eastern South Africa. The fossils were found there during a highway construction.
features
Diskagma buttonii reached a height of about 0.3 to 1.8 mm. Investigations on hundreds of thin section samples showed significant differences in growth and decay. The best preserved specimens were urn-shaped with an enlarged rim and closed at the bottom. The interior was hollow and elliptical. Diskagma bears some resemblance to lichens of the genus Cladonia and mushrooms of the genus Geosiphon .
meaning
With an age of 2.2 billion years, Diskagma buttonii is much older than the oldest known fossils of unicellular eukaryotes (1.9 billion years), older than the oldest mushrooms (1.5 billion years) and also older than that Age of eukaryotes (1.6 billion years) and fungi (1.1 billion years) determined with the help of the molecular clock . In the first description one assumes a mycorrhizal fungus from the group of Archaeosporales or a related group. This is not compatible due to the younger age of fungi, which was calculated with the help of the molecular clock . However, the method of the molecular clock is not yet fully understood. The relationship and identity of Diskagma thus remains uncertain, but the fossils show the general appearance of rural life during the Paleoproterozoic and shift the landfall of living beings, previously limited to a period from 400 to 600 million years ago, far into the past to a time when in which the oxygen content in the earth's atmosphere was only 0.9 to 5%.
literature
- Gregory J. Retallack, Evelyn S. Krull, Glenn D. Thackray, Dula Parkinson: Problematic urn-shaped fossils from a Paleoproterozoic (2.2 Ga) paleosol in South Africa. Precambrian Research, Volume 235, September 2013, pp. 71-87, doi: 10.1016 / j.precamres.2013.05.015
Individual evidence
- ↑ Michael Krings, Thomas N. Taylor, Carla J. Harper: Early fungi: Evidence from the fossil record. in The Fungal Community, Its Organization and Role in the Ecosystem , Edition: 4, Chapter: 3, Publisher: CRC taylor and Francis, Editors: J. Dighton, JF White, pp. 37-52
- ^ L. Paul Knauth: Not all at sea. In: Shuhai Xiao, L. Paul Knauth: Forum Palaeontology: Fossils come in to land. In: Nature . Volume 493, No. 7430, 2013, pp. 28-29, doi: 10.1038 / nature11765
- ^ Gregory J. Retallack: Ediacaran life on land. In: Nature. Volume 493, No. 7430, 2013, pp. 89-92, doi: 10.1038 / nature11777
Web links
- Science Daily: Greening of the Earth Pushed Way Back in Time
- sci-news.com: Two Billion Year Old Fossils Point to Early Terrestrial Life