Paleoproterozoic
| Aeonothem | Arathem | system | Age ( mya ) |
|---|---|---|---|
| later | later | later | |
|
P r o t e r o z o i k u m Duration: 1959 Ma |
Neoproterozoic Jungproterozoikum Duration: 459 Ma |
Ediacarium | 541 ⬍ 635 |
| Cryogenium | 635 ⬍ 720 |
||
| Tonium | 720 ⬍ 1000 |
||
|
Mesoproterozoic Mittelproterozoikum Duration: 600 Ma |
Stenium | 1000 ⬍ 1200 |
|
| Ectasium | 1200 ⬍ 1400 |
||
| Calymmium | 1400 ⬍ 1600 |
||
|
Paleoproterozoic Altproterozoikum Duration: 900 Ma |
Statherium | 1600 ⬍ 1800 |
|
| Orosirium | 1800 ⬍ 2050 |
||
| Rhyacium | 2050 ⬍ 2300 |
||
| Siderium | 2300 ⬍ 2500 |
||
| earlier | earlier | earlier |
The Paleoproterozoic ( = Old Proterozoic ) is an era in the history of the earth. Within the eon of the Proterozoic it represents the oldest era is, it starts before about 2500 and ends before 1600 million years ago. It is also the longest era in the history of the earth.
Atmosphere in the Paleoproterozoic
In the Paleoproterozoic, the oxygen concentration in the atmosphere increased to> 1%. The strong tectonic activity steadily led to the formation and disintegration of continents. The strong climatic fluctuations caused by the tectonic activities accelerated the erosion of the land masses according to the principle of positive feedback . The erosion in turn created an increased supply of nutrients into the oceans, which led to increased primary production . The primary producers included the ancestors of today's cyanobacteria , whose photosynthetic activity caused the concentration of free oxygen in the atmosphere and in seawater to rise. The increased occurrence of free oxygen in the earth's atmosphere had serious consequences for a large number of the anaerobic microorganisms, the most numerous life forms up to this point in time. The build-up was toxic to many of the microbial species. The rise in oxygen levels led to the first major mass extinction in Earth's history. Since this change was slow compared to the man-made increase in greenhouse gases in the atmosphere, many life forms were able to adapt to the new environmental conditions and even benefit from them. The formation of ozone in the stratosphere made it possible for the first time to colonize the mainland through protection against UV radiation . The consequences of the increasing oxygen content were also the precipitation of iron and thus the formation of strip ores in the sea water and the expansion of large-scale manganese deposits.
biology
Unicellular life continued to develop during the Paleoproterozoic. The first complex single cells with organelles and later also a cell nucleus ( eukaryotes ) developed from simple bacteria . This also included the first green algae and the first single-celled animals. Fossils with characteristics typical of mushrooms have also been found in 2.4 billion year old basalt. These multicellular benthic organisms had filamentous structures that were capable of anastomosis .
Subdivision of the Paleoproterozoic
The subdivision of the Paleoproterozoic:
- Eon : Phanerozoikum (541-0 mya )
-
Eon : Proterozoikum (2500-541 mya)
- Era : Neoproterozoic (1000-541 mya)
- Era: Mesoproterozoic (1600–1000 mya)
- Era: Paleoproterozoic (2500–1600 mya)
- Period : Statherium (1800–1600 mya)
- Period: Orosirium (2050–1800 mya)
- Period: Rhyacium (2300-2050 mya)
- Period: Siderium (2500–2300 mya)
- Eon: Archean (4000-2500 mya)
- Eon: Hadean (4600-4000 mya)
See also
Individual evidence
- ^ Stefan Bengtson, Birger Rasmussen, Magnus Ivarsson, Janet Muhling, Curt Broman: Fungus-like mycelial fossils in 2.4-billion-year-old vesicular basalt. In: Nature ecology & evolution . tape 1 , no. 6 , April 24, 2017, ISSN 2397-334X , p. 141 , doi : 10.1038 / s41559-017-0141 ( escholarship.org [accessed March 29, 2020]).