WASHINGTON — Scientists at the Swedish Museum of Natural History have discovered fossils of 1.6 billion-year-old which look like red algae may represent the earliest-known plants, a discovery that could force scientists to reassess the timing of when major lineages in the tree of life first appeared on Earth.
The spectacular findings, published on Tuesday (14 March 2017) in the open access journal PLOS Biology, indicate that advanced multicellular life evolved much earlier than previously thought.
The scientists found two kinds of fossils resembling red algae in uniquely well-preserved sedimentary rocks at Chitrakoot in central India. One type is thread-like, the other one consists of fleshy colonies.
“We almost could have had sushi 1.6 billion years ago,” joked Swedish Museum of Natural History geobiologist Therese Sallstedt, who helped lead the study.
The researchers said cellular structures preserved in the fossils and their overall shape match red algae, a primitive kind of plant that today thrives in marine settings such as coral reefs but also can be found in freshwater environments. A type of red algae known as nori is a common sushi ingredient.
“You cannot be a hundred per cent 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 emeritus of palaeozoology at the Swedish Museum of Natural History.
The earliest traces of life on Earth are at least 3.5 billion years old. 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 oldest known red algae before the present discovery are 1.2 billion years old. The Indian fossils, 400 million years older and by far the oldest plant-like fossils ever found, suggest that the early branches of the tree of life need to be recalibrated.Follow @gorkhapost