Origins Of Photosynthesis





Science, 21 Dec - 2017 ,

Origins Of Photosynthesis
The Angmaat Formation above Tremblay Sound on the Baffin Island coast. Bangiomorpha pubescens fossils occur in this roughly 500-meter thick rock formation. Credit: Timothy Gibson

The world's oldest algae fossils are a billion years old, according to a new analysis by earth scientists at McGill University. Based on this finding, the researchers

The world's oldest algae fossils are a billion years old, according to a new analysis by earth scientists at McGill University. Based on this finding, the researchers also estimate that the basis for photosynthesis in today's plants was set in place 1.25 billion years ago.

The study, published in the journal Geology, could resolve a long-standing mystery over the age of the fossilized algae, Bangiomorpha pubescens, which were first discovered in rocks in Arctic Canada in 1990. The microscopic organism is believed to be the oldest known direct ancestor of modern plants and animals, but its age was only poorly dated, with estimates placing it somewhere between 720 million and 1.2 billion years.

The new findings also add to recent evidence that an interval of Earth's history often referred to as the Boring Billion may not have been so boring, after all. From 1.8 to 0.8 billion years ago, archaea, bacteria and a handful of complex organisms that have since gone extinct milled about the planet's oceans, with little biological or environmental change to show for it. Or so it seemed. In fact, that era may have set the stage for the proliferation of more complex life forms that culminated 541 million years ago with the so-called Cambrian Explosion.

Origins of the chloroplast

Once the researchers had gauged the fossils' age at 1.047 billion years, they plugged that figure into a "molecular clock," a computer model used to calculate evolutionary events based on rates of genetic mutations. Their conclusion: the chloroplast must have been incorporated into eukaryotes roughly 1.25 billion years ago.


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