Scientists from the Australian National University (ANU) and overseas have discovered 1.1 billion-year-old bright pink pigments extracted from rocks deep beneath the Sahara desert in Africa. These are reportedly the oldest colours found in the geological record.
A study published on July 9, 2018 in the Proceedings of the National Academy of Sciences revealed that the pigments taken from marine black shales of the Taoudeni Basin in Mauritania, West Africa, were more than half a billion years older than previous pigment discoveries.
“The bright pink pigments are the molecular fossils of chlorophyll that were produced by ancient photosynthetic organisms inhabiting an ancient ocean that has long since vanished,” said Dr Gueneli from the ANU Research School of Earth Sciences in a statement.
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According to the study, the fossils range from blood red to deep purple in their concentrated form, and bright pink when diluted.
The billion-year-old rocks had to be crushed to powder before researchers could extract and analyse molecules of ancient organisms from them.
“The precise analysis of the ancient pigments confirmed that tiny cyanobacteria dominated the base of the food chain in the oceans a billion years ago, which helps to explain why animals did not exist at the time,” said Dr Gueneli, who had discovered the molecules as part of her PhD studies.
Senior lead researcher Dr Jochen Brocks from the ANU Research School of Earth Sciences said that the emergence of large, active organisms was likely to have been restrained by a limited supply of larger food particles, such as algae.
“Algae, although still microscopic, are a thousand times larger in volume than cyanobacteria, and are a much richer food source,” explained Dr Brocks.
“The cyanobacterial oceans started to vanish about 650 million years ago, when algae began to rapidly spread to provide the burst of energy needed for the evolution of complex ecosystems, where large animals, including humans, could thrive on Earth,” he added.
This research was carried out by ANU with support from Geoscience Australia and researchers in Japan and the United States.