Up to 800 million years ago, the Earth’s oceans were deprived of oxygen. It was only when marine planktonic cyanobacteria colonised the oceans – covering two thirds of our planet – that production of oxygen at a massive scale was made possible. This evolutionary event set the stage for a fundamental transformation of our planet – linking the evolution of complex life, extreme glaciation events (e.g., Snowball Earth) and the beginning of our modern Earth System. This research has been published in Scientific Reports (Sánchez-Baracaldo, P 2015; doi: 10.1038/srep17418).
Figure 2: Timing and trends in cell diameter, loss of filamentous forms and habitat preference within cyanobacteria.
The diagram in Figure 2 illustrates that oxygenic photosynthesis originated in freshwater habitats. For most of the Precambrian cyanobacteria were restricted to freshwater/terrestrial and costal marine habitats.
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