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Precambrian Life |
| Updated: 4/9/98 |
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Following its origins, the record of life on earth is limited to stromatilites and bacterial microfossils until development of the metazoans in the late Precambrian. From 3.5 billion years to around 1.8 billion years the fossil record is dominated by prokaryotes. Between 2.5 and 1.8 billion years ago, major changes in the hydrosphere and atmosphere paved the way for the development of eukaryote cells. The rise of free O2 produced through bacterial photosynthesis is recorded in the changing nature of sedimentary rocks. Through Banded-Iron Formations, uraninite deposits, and terrestrial red-beds, we see oxidation of ocean waters and atmosphere. As the atmosphere and hydrosphere changed, so did the biosphere. Development of complex eukaryote cells allowed increasing differentiation of cell types and led to the development of multicellular plants and animals. By the late Precambrian (Proterozoic), soft-bodied metazoans begin to dominate the fossil record. Lecture Notes: Study Guide:
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