The search to find what caused one of the most important evolutionary events in the tale of life on our planet has taken an unexpected turn. A team of researchers has come with new ideas regarding the cause of the ‘Cambrian Explosion,’ a period of quick expansion of several animal life forms that happened about 500 million years ago.
There were numerous theories put forward, but the most credible one is that the expansion was fueled by a high rise in oxygen levels, which enabled a large variety of animals to thrive. New research implies that such an increase in oxygen levels was the outcome of incredible changes in the global plate tectonics.
While the supercontinent ‘Gondwana’ was forming, there was a considerable increase in ‘continental arc volcanism,’ namely chains of volcanoes thousands of miles long which formed where continental and oceanic tectonic plates crashed. This conducts to increased ‘degassing’ of CO2 from ancient, subducted sedimentary rocks.
Therefore, the scientists calculated, this conducted to a rise in atmospheric CO2 and warming of the planet, which then increased the erosion of continental rocks, which provided the nutrient phosphorus to the ocean to lead photosynthesis and oxygen production.
Cambrian Explosion triggered by global tectonic plates
The research was led by Josh Williams, who is now studying for a Ph.D. at the University of Edinburgh. In his previous project, Williams used a complex biogeochemical model to generate the first quantification of changes in atmospheric oxygen levels just before this outburst of life.
Professor Tim Lenton, co-author and project supervisor from the University of Exter’s Global Systems Institute, said that one of the greatest mysteries initially mentioned by Darwin is the reason why sophisticated life, in the shape of fossil animals, showed up so suddenly in the Cambrian Explosion.
The model used in the study predicts a marked increase in oxygen levels because of changes in plate tectonic activity. However, that rise passed the critical levels thought to be needed by the animals observed in the Cambrian Explosion.
Williams explained that the model also shows a steady connection to the existing geochemical evidence. A tectonically driven Ediacaran oxygenation event by Joshua Williams, Benjamin Mills and Tim Lenton is issued in the journal Nature Communications on June the 19th, 2019.