Pedigree of primates. Credit: MA Klingler / Carnegie Museum of Natural History
A tiny creature flopped into a lake in present-day China - 55 million years later, its remains are now becoming a scientific sensation: its well-preserved fossil represents the oldest known representative of the primate pedigree, including humans. According to research by an international team of researchers, this is a primeval species from the lineage of today's leprechaun mackerel. As a result, the primate pedigree branched 55 million years ago. The fossil comes from a site in Hubei Province, China, near the Yangtze River. There was a lake around 55 million years ago, in whose sediments fossils have been particularly well preserved. They are embedded in the layers of sedimentary rock as in a puff pastry - including the remains of the early primate. As a result, not only has his skeleton been preserved, but there is also a two-sided imprint of the being in the rock.

Researchers led by Xijun Ni of the Chinese Academy of Sciences in Beijing recorded the structure of the fossil by means of extensive X-ray images. In this way, the filigree skeleton did not have to be completely freed from the rock - so a nondestructive investigation was possible. From the images, the researchers were finally able to create a three-dimensional computer model of the tiny creature that allowed accurate anatomical analysis. "The three-dimensional scans literally brought the creature back to life, " says co-author Paul Tafforeau of the European Synchrotron Radiation Facility in Grenoble.

An exciting little thing

The 3D model finally revealed the features of the primal primate that the researchers christened Archicebus achilles. He was only about 71 mm tall and his estimated weight was 20-30 grams. The sharp teeth and the construction of his extremities suggest that Archicebus hopped from branch to branch to grapple with insects. Presumably he was not a hunter of the night, but diurnal, the researchers suspect the properties of his eye sockets. Certain aspects of his anatomy suggest that it was an early representative of the lineage of the goblin mackerel (Tarsiidae), the scientists report. Today's species occur on the Southeast Asian islands, where they look for night insects with their huge eyes. This primate group forms a sub-branch of the branch of the so-called dry-nasal primates. This forks between Tarsiidae and the Anthropoidea, to which the apes and also humans belong. display

According to the researchers' findings, the newly discovered creature has characteristics that suggest that the split between these two lines of development had already taken place some 55 million years ago. "Although Archicebus appears to be a member of the Tarsiidae lineage, it also has some features that link it to the anthropoidea, including its comparatively small eyes and the anatomy of its feet, explains co-author Marian Dagosto of Northwestern University in Chicago, Its small size also indicates that the early ancestors in the primate pedigree were all tiny, say the researchers.
The oldest known representatives of the evolutionary history of primates are seven million years younger than Archicebus achilles. In addition, these earlier finds were entities associated with the Lemurs lineage. This had split off earlier in the history of development from the pedigree of the primates - Archicebus is evolutionarily closer to us. That makes the little thing so exciting and now the subject of many other analyzes, the researchers say.

Xijun Ni (Chinese Academy of Sciences, Beijing) et al .: Nature, doi: 10.1038 / nature12200 © science.de - Martin Vieweg

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