At 1.6bn years old, could red algae be the oldest plant-like fossil?

15 Mar 2017

Red algae. Image: Dudarev Mikhail/Shutterstock

Scientists in Sweden claim to have discovered the oldest known plant-like fossil, with red algae the probable candidate.

From India to Sweden, a new archaeological discovery could overhaul previous conceptions of life on Earth.

Scientists at the Swedish Museum of Natural History have found 1.6bn-year-old plant-like fossils, something they consider to most likely be red algae.

The scientists found two kinds of fossils in well-preserved sedimentary rocks at Chitrakoot in central India. One type is thread-like, the other one consists of fleshy colonies.

“You cannot be 100pc 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 Stefan Bengtson of the Swedish Museum of Natural History, who led the study.

Discoveries of this type of fossil – early multicellular eukaryotes – are difficult to understand and prove, meaning that the oldest strands of Earth’s tree of life are not the easiest thing to pin down.

Before this discovery, the oldest known red algae were thought to be 1.2bn years old – 400m years younger than this development. This, in turn, means that the history of life on this planet must be re-evaluated.

“The ‘time of visible life’ seems to have begun much earlier than we thought,” said Bengtson.

X-ray tomographic picture (false colors) of fossil thread-like red algae. Image: Stefan Bengston

X-ray tomographic picture (false colours) of fossil thread-like red algae. Image: Stefan Bengston

The earliest traces of life on Earth are at least 3.5bn years old, though a recent discovery in Canada hints at something far older.

Earlier this month, scientists from University College London landed the find of their lifetimes, with fossils potentially dating back between 3.77bn and 4.28bn years ago.

Earth’s oldest rocks are more than 4bn years old. Earth itself is 4.5bn years old.

The fossils are tiny (1cm in size) filaments and tubes, which the research team claims were formed by bacteria that lived on iron. They were found encased in quartz layers in the Nuvvuagittuq Supracrustal Belt in Quebec.

The location is important as Nuvvuagittuq is home to some of the oldest sedimentary rocks ever known, likely part of an iron-rich deep-sea hydrothermal vent system, which helped to create life on the planet.

Gordon Hunt was a journalist with Silicon Republic