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Ankle fossil says our ancestors were great at leaping

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Our pre-human ancestors had legs that allowed them to jump long distances, a 52-million-year-old ankle fossil suggests.

The first primates spent most of their time in the trees rather than on the ground, but just how nimble they were as they moved around in the treetops has been a topic of dispute.

For years, scientists thought the ancestors of today’s humans, monkeys, lemurs, and apes were relatively slow and deliberate animals, using their grasping hands and feet to creep along small twigs and branches to stalk insects or find flowers and fruits.

But a fossil study published in the Journal of Human Evolution suggests the first primates were actually masters at leaping through the trees.

ankle fossil

“Being able to jump from one tree to another might have been important, especially if there were ground predators around waiting to snag them.” (Credit: Douglas Boyer/Duke)

The quarter-inch-long bone, the lower part of the ankle joint—found in a quarry in southeastern France—matched up best with a chipmunk-sized creature called Donrussellia provincialis.

Previously only known from jaws and teeth, Donrussellia is thought be one of the earliest members of the primate family tree, on the branch leading to lemurs, lorises, and bush babies.

Researchers studied scans of Donrussellia’s ankle and compared it to other animals, using computer algorithms to analyze the 3D digital shape of each tiny bone and were surprised to find that it was not like those of other primates, but was more similar to those of treeshrews and other nonprimate species.

The analyses also suggest the animal didn’t just clamber or scurry along small branches. Instead, it may have been able to leap between trunks and branches, using its grasping feet to stick the landing.

Contrary to what many scientists thought, the first primates may have evolved their acrobatic leaping skills first, while anatomical changes that allowed them to cling to slender branch tips and creep from tree to tree came later, says Doug Boyer, an assistant professor at Duke University.

“Being able to jump from one tree to another might have been important, especially if there were ground predators around waiting to snag them.”


This text is published here under a Creative Commons License.
Author: Robin Smith-Duke University
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