Artistic reconstruction of Archicebus achilles in its natural habitat of trees.
The creature is around 55 million years old and seems to be the earliest and most primitive known relative of the tarsiers. As tarsiers are related to anthropoids — the primates that include monkeys, apes and humans — the discovery shows that the lineage leading ultimately to humans was distinct at a very early date.
The primitive primate skeleton unearthed by Xijun Ni and colleagues is from the early Eocene (55.8–54.8 million years ago) of China. Analysis of the skeleton reveals a mixture of features — some that resemble anthropoids and some that resemble tarsiers. Its name, Archicebus achilles, roughly translates as ‘ancient monkey’ and also makes a cheeky reference to the animal’s anthropoid-like heel bone. These findings show that the age of the split between the Tarsiiformes and anthropoids, from which humans descend, is earlier than previously thought.
The tiny primate has a body that is around 71 mm long and its estimated weight is around 20–30 grams, as small as a modern pygmy mouse lemur. Certain features of the skeleton suggest that the creature was a frequent leaper, favouring four-limbed grasp-leaping as a mode of transport. Small pointy teeth indicate that it ate insects. Large eye sockets indicate that the creature had good vision for hunting, but evidence points towards a diurnal rather than nocturnal activity pattern.
CONTACT
Xijun Ni (Chinese Academy of Sciences, Beijing, China)
Tel: +86 10 8836 9270; E-mail: [email protected]
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Neda Afsarmanesh, Nature New York
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Caption: Illustration of an evolutionary tree, showing how Archicebus fits with respect to primate phylogeny.
Reconstruction of the fossil of Archicebus achilles, based on microtomography scanning.
