
Cast of the Sahelanthropus tchadensis skull
Didier Descouens CC BY-SA 4.0
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The period between 7 million and 4 million years ago is a bit of a nebulous phase in the story of human evolution. There are basically four data points: Sahelanthropus tchadensis from 7 million years ago, Orrorin tugenensis from 6 million years ago and the two species of Ardipithecus from 5.6 million and 4.4 million years ago. Each is known…


![Australopithecus sediba silhouette showing the newly-found vertebrae along with other skeletal remains from the species. The enlarged detail (a photograph of the fossils in articulation on the left; micro-computed tomography models on the right) shows the newly discovered fossils, in colour on the right between previously known elements in grey. Right: Life reconstruction of Australopithecus sediba com-missioned by the University of Michigan Museum of Natural History. [? Sculpture: Elisabeth Daynes / Photograph: S. Entres?sangle]](https://images.newscientist.com/wp-content/uploads/2021/11/23130516/PRI_211648445.jpg)
