• Scientists in India have uncovered a pair of 1.6 billion-year-old fossils that appear to contain red algae, which may be the oldest plant-like life discovered on Earth.
• Until now, the oldest known red algae was 1.2 billion years old, said the paper in the journal PLOS Biology .
• Scientists often debate the question of when complex life began on Earth, but they generally agree that large multicellular organisms became common about 600 million years ago.
• This discovery could lead experts to rewrite the tree of life, said lead author Stefan Bengtson, Professor Emeritus of palaeo-zoology at the Swedish Museum of Natural History.

Findings:

• “The ‘time of visible life’ seems to have begun much earlier than we thought.
• No DNA remains in the fossils to be analysed but the material structurally resembles red algae, embedded in fossil mats of cyanobacteria inside a 1.6 billion-year-old phosphorite, a kind of sedimentary rock.
• “You cannot be a hundred percent sure about material this ancient, as there is no DNA remaining, but the characters agree quite well with the morphology and structure of red algae.
• Advanced tools — such as synchrotron-based X-ray tomographic microscopy — allowed scientists to observe regularly recurring platelets in each cell, which they believe are parts of chloroplasts, the organelles within plant cells where photosynthesis takes place.
• Distinct structures at the centre of each cell wall are also apparent, and are typical of red algae.
• The fossils were discovered in sedimentary rocks in the Chitrakoot region of Uttar Pradesh and Madhya Pradesh.
• The earliest traces of life on Earth — in the form of single-celled organisms — go back some 3.5 billion years.