WASHINGTON, July 9 (Xinhua) -- Scientists have discovered the oldest colors in the geological record, 1.1 billion-year-old pigments extracted from rocks deep beneath the Sahara desert in Africa.
A study published on Monday 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 Nur Gueneli from the Australia National University (ANU) Research School of Earth Sciences and the paper's first author.
The fossils range from blood red to deep purple in their concentrated form, and bright pink when diluted, according to the study.
The researchers crushed the billion-year-old rocks to powder, before extracting and analyzing 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," Gueneli said.
The paper's senior lead researcher Jochen Brocks with ANU 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," said 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," said Brocks.