WASHINGTON, March 14 (Xinhua) -- Two fossils believed to the world's oldest known plant-like life have been found in India, indicating that advanced multicellular life evolved much earlier than previously thought, a new study said Tuesday.
The fossils resembling probable red algae were unearthed in 1.6-billion-year-old sedimentary rocks at Chitrakoot in central India, according to the study published in the open access journal PLOS Biology.
The oldest known red algae before the present discovery are 1.2 billion years old.
The researchers said that one of the fossils is thread-like while the other one has complex, fleshy structures.
The scientists were also able to see distinct inner cell structures and so-called cell fountains, the bundles of packed and splaying filaments that form the body of the fleshy forms and are characteristic of red algae.
"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," said study author Stefan Bengtson, professor of the Swedish Museum of Natural History.
The earliest traces of life on Earth are at least 3.5 billion years old and these single-celled organisms, unlike eukaryotes, lack nuclei and other organelles.
Large multicellular eukaryotic organisms became common much later, about 600 million years ago, near the transition to the Phanerozoic Era, the "time of visible life."
The Indian fossils, by far the oldest plant-like fossils ever found, suggested that the early branches of the tree of life need to be recalibrated.
"The 'time of visible life' seems to have begun much earlier than we thought," Bengtson added.