A team of researchers announces they have discovered what appears to be the oldest known evidence of plant life on Earth: two fossils of what appear to be 1.6 billion-year-old red algae suggesting that advanced multicellular life originated much sooner than we thought.
The fossils were discovered in sedimentary rocks in Chitrakoot, central India according to the study published in the journal PLoS One. The traces, dated to 1.6 billion years ago, predate the oldest known sample of red algae dated to 1.2 billion years by 400 million years, suggesting that multicellular life evolved much earlier. earlier than previously thought and calling into question the Great Cambrian Explosion that gave rise to most of the major groups of animals present on Earth today.
» You cannot be 100% sure about the nature of these fossils, as there is no DNA remaining. But the characteristics correspond quite well to the morphology and structure of red algae says study author Stefan Bengtson, a professor at the Swedish Museum of Natural History. The oldest traces of life on Earth date back at least 3.5 billion years. But these single-celled organisms do not have nuclei or other organelles unlike eukaryotes.
The researchers say they have studied the fossils using tomography, an X-ray microscopy imaging technique that allows them to identify internal cell structures that they suspect are parts of the chloroplast where photosynthesis occurs in plants. In particular, they identified bundles of filaments that form the characteristic fleshy part of red algae, leading scientists to suspect that these creatures are the oldest samples of red algae ever discovered.
If verified, the discovery also challenges our a priori assumptions about the Cambrian explosion which is thought to have started between 550 to 545 million years ago. This unique period in Earth’s history gave rise to most of the major animal phyla on the planet, but this discovery suggests that the event began much earlier than we thought, developing gradually. Of course, without DNA evidence to back up these claims, we’ll never know for sure if these fossils represent the earliest evidence of plant life on Earth.