Fossils from West Africa: Researchers Wanted to Have Discovered the Earliest Evidence of Locomotion
In Africa, researchers have come across strange corridors in petrified seabed. What was creeping through the mud over two billion years ago?
It may be the oldest fossilized traces of living organisms: In Gabon, West Africa, paleontologists have discovered corded appearances in 2.1 billion year old rocks. The fossils come from amoeba-like creatures that have formed into a larger entity, researchers around Abderrazak El Albani from the University of Poitiers (France) believe.
The oldest known such remains are 570 million years old. The study has appeared in the Proceedings of the US Academy of Sciences.
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The fossils are from slate and fine sandstone and were found in the Franceville Basin in Gabon. Here was about 2.1 billion years ago a territorial sea. The deposits from the seabed are preserved today in the rock. The tracks found are one to six millimeters wide and up to 17 inches long.
To investigate their discovery, the researchers used combined microscopic, microtomographic and geochemical analyzes. As a clue to the way of life that caused the traces, a group of today's slime molds, termed Dictyosteliida, serves them.
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In the process, amoebae, ie unicellular organisms, join together to form a larger entity, which can take on the shape of a nudibranch. This happens when the food, mostly bacteria, becomes scarce and the amoebae have to reach new food sources. If the traces were from bacteria, the filamentous deposits would have had to be narrower, the researchers write.
Because of the microbial films found, El Albani and colleagues suggest that a similar process led to the aisles two billion years ago. According to this, amoeba-like protozoans have teamed up in the bottom of a shallow seabed to search for a new microbe film. The mucus lined tunnels are then soon petrified.
In the same rock formation, a team around El Albani had already described in 2010 other fossils, which today are referred to as "Gabonionta". They are also up to 17 inches tall and are considered the oldest form of multicellular organisms. However, the interpretation of these structures is controversial. There are also assumptions that they could have come about in the rock without the action of living things. If the interpretation of El Albani prevailed at the time, multicellular organisms would be 2.1 billion years old, 1.5 billion years older than previously proven.
In the history of the earth, traces of organisms are sometimes difficult to distinguish from purely geochemical deposits. Several times it has come to confusion.