Swedish scientists have found fossils dating back to 1.6 billion-year-old resembling red algae in Chitrakoot rocks, by far the oldest plant-like fossils ever found, suggesting that the early life form belonged here on earth and the advanced multicellular life evolved much earlier than previously thought.
The scientists found two kinds of fossils in sedimentary rocks at Chitrakoot in central India – one is thread-like and the other is of fleshy colonies. The scientists were able to see distinct inner cell structures and cell fountains that form the fleshy forms of red algae.
"You cannot be a 100% 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," says Stefan Bengtson, Professor of palaeozoology at the Swedish Museum of Natural History.
The earliest known fossil evidence of life on Earth are at least 3.5 billion years old. These single-celled organisms, unlike eukaryotes, lack nuclei. The oldest known red algae before the present discovery are 1.2 billion years old. "The ‘time of visible life’ seems to have begun much earlier than we thought," said Stefan Bengtson.
The presumed red algae was found in the form of fossil mats of cyanobacteria, called stromatolites, in 1.6 billion-year-old Indian phosphorite. The thread-like forms were discovered first by Therese Sallstedt, then doctoral student who investigated the stromatolites and found them more complex, fleshy.
"I got so excited I had to walk three times around the building before I went to my supervisor to tell him what I had seen!" she said. The research group was able to look inside the algae with the help of synchrotron-based X-ray tomographic microscopy.
X-ray tomographic picture (false colors) of fossil thread-like red algae.CREDIT: Stefan Bengtson