Bengaluru: Scientists have discovered a new species of multicellular green algae that is a billion-year-old and believed to be one of the oldest known fossils of green algae.
Named Proterocladus antiquus, the fossilised remains of the plant were found in a 1,000-million-year-old rock formation in China. This new species is only about 1-2 millimetres in size.
The discovery was made by a team of researchers from Virginia Tech and the results were published in the Nature Ecology and Evolution.
The new discovery is likely to bring scientists one step closer to understanding when photosynthesising plants had first evolved. One of the biggest mysteries in palaeoscience is when exactly the first green plant (or algae) came into being.
The birth and multiplication of multicellular green algae that can perform photosynthesis had set off a cataclysmic change in the earth’s ecosystem, by giving rise to plants and trees.
Until then, the planet only had single-cell microbes and cyanobacteria — the organisms that first performed photosynthesis and filled the environment with oxygen.
The team of scientists also discovered that the new algae were in abundant quantities — there were 1,028 individual specimens found. This is significant since the survival of such a tiny organism in the fossil record is considered difficult. Abundant quantities of the algae implies that it had thrived when it existed.
The researchers have argued that this new algae species died in the shallow ocean and were “cooked” under a layer of sediment which ultimately helped preserve them.
New algae is a sea weed
The researchers have said that the new algae, essentially a sea weed, stood upright on the sea floor by using its root and branch-like structures. The study also states that an existing algae belonging to a modern green seaweed group called siphonocladaleans are very similar to the fossils.
Genetic analysis of the kinds of algae suggest that green algae is much older than red algae. But red algae fossils that have been discovered till date are older than those of the Proterocladus antiquus.
The oldest red algae fossils that have been found are over 50 million years older than the newly-discovered green algae.
Scientists have earlier discovered 1.6 billion-year-old fossils of red algae in Uttar Pradesh’s Chitrakoot. But it is likely that an older green algae may be discovered some time in the future.
Red and brown algae also perform photosynthesis but by using different parts of the light spectrum.
It is thought that multicellular organisms evolved around 600 million years ago, the first vertebrates 470 million years ago and the first plants only 430 million years ago. Until then, algae were the only multicellular plants on earth.