Paleontology: When early humans got up on their feet

Sahelanthropus tchadensis, one of the oldest known hominins (Sahelanthropus tchadensis) was bipedal 700 million years ago, according to analysis of fossils of the thigh and forearm.The findings build on previous analyzes that reached similar conclusions.A paper reporting on the research is published in Nature.

In 2001, a large amount of fossils was discovered in Chad's Talos Menara, leading to the naming of a new species of early hominin (a taxon that includes extinct species closely related to modern humans), Sahelanthropus tchadensis, which was dated to approximately Turned out to be a 700 million year old hominin race.Analysis of the nearly intact skull also suggests that Sahelanthropus may have walked on two legs, a defining hominin trait of "upright bipedal locomotion".Regarding this hypothesis, a research report on arm and leg bones excavated in the same area around the same time has already been reported, and we had an opportunity to verify it using it.

Guillaume Daver, Franck Guy and colleagues present the results of an analysis of a left thighbone (femur) and a pair of forearm bones (ulnae) from the site where the Sahelanthropus fossil was found in 2001. made itThe anatomy of the femur indicates that Sahelanthropus was bipedal on land about 1 million years ago, corroborating the predictions made by evidence from the skull.In addition, the authors cautiously emphasize that ulnar features are consistent with traits that are characteristic of tree-climbing adaptations.For example, the functional pattern of the ulna suggests that Sahelanthropus climbed and descended trees, possibly by some form of grasping or erratic limb movement.

Together, the evidence suggests that soon after humans and chimpanzees diverged, early humans acquired the ability to walk on two legs and retained the skeletal features that enabled them to climb trees. Daver et al. conclude that they do.

doi: 10.1038 / s41586-022-04901-z
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Reprinted from: "Palaeontology: When early humans began walking on two legs'

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