Photosynthesis has possibly been dated at 1.25 billion years ago with a new study claiming that it was during those times that the basis of photosynthesis emerged.
The new study published in journal Geology is based on fossilized algae, Bangiomorpha pubescens, which was found in 1990 from Arctic Canada. Scientists have long tried to date the fossilized algae, but without much success. However, Scientists at McGill University managed to determine the age of the algae and thereby also finding out when photosynthesis was first carried out by plants.
To pinpoint the fossils’ age, the researchers pitched camp in a rugged area of remote Baffin Island, where Bangiomorpha pubescens fossils have been found. Researchers collected samples of black shale from rock layers that sandwiched the rock unit containing fossils of the alga. Using the Rhenium-Osmium (or Re-Os) dating technique, applied increasingly to sedimentary rocks in recent years, they determined that the rocks are 1.047 billion years old.
Scientists at McGill university and colleagues reveal that the organism is believed to be the oldest known direct ancestor of modern plants and animals. Because Bangiomorpha pubescens is nearly identical to modern red algae, scientists have previously determined that the ancient alga, like green plants, used sunlight to synthesize nutrients from carbon dioxide and water.
Scientists have also established that the chloroplast, the structure in plant cells that is the site of photosynthesis, was created when a eukaryote long ago engulfed a simple bacterium that was photosynthetic. The eukaryote then managed to pass that DNA along to its descendants, including the plants and trees that produce most of the world’s biomass today.
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.