Nature is providing free, unrestricted access to an important new paper about 'Toumai', an ancient human skull found in Africa.

From NYT Week In Review: The known history of human origins took a vaulting leap back in time: French scientists announced that a seven-million-year-old skull found in the central African country of Chad is the oldest member of the human family yet discovered, by as much as a million years.

Paleontologists think this is the most important fossil find in decades. The skull comes from a region beyond the usual track of fossil hunters and affords a glimpse into the little-known period when human precursors and chimpanzees diverged from a common ancestor. One surprise is the skull's mosaic of apelike and advanced characteristics, suggesting a pattern of evolution more tangled than the usual linear family trees.

From Nature: At between 6 and 7 million years old, this skull is the earliest known record of the human family. Discovered in Chad in Central Africa, the new find, nicknamed 'Toumaï', comes from the crucial yet little-known interval when the human lineage was becoming distinct from that of chimpanzees. Because of this, the new find will galvanize the field of human origins like no other in living memory -- perhaps not since 1925, when Raymond Dart described the first 'ape-man', Australopithecus africanus, transforming our ideas about human origins forever. A lifetime later, Toumaï raises the stakes once again and the consequences cannot yet be guessed. Dart's classic paper was published in Nature, as have most of the milestones in human origins and evolution. To celebrate the new find, we are proud to offer a selection of ten of the very best from Nature's archives, including Dart's classic paper.