Dating a fossil
The centerpiece of a treasure trove of new fossils, the skeleton—assigned to a species called Ardipithecus ramidus—belonged to a small-brained, 110-pound (50-kilogram) female nicknamed "Ardi." (See pictures of Ardipithecus ramidus.) The fossil puts to rest the notion, popular since Darwin's time, that a chimpanzee-like missing link—resembling something between humans and today's apes—would eventually be found at the root of the human family tree.
Ardi instead shows an unexpected mix of advanced characteristics and of primitive traits seen in much older apes that were unlike chimps or gorillas (interactive: Ardi's key features).
As such, the skeleton offers a window on what the last common ancestor of humans and living apes might have been like.
Radiometric dating of two layers of volcanic ash that tightly sandwiched the fossil deposits revealed that Ardi lived 4.4 million years ago.
Older hominid fossils have been uncovered, including a skull from Chad at least six million years old and some more fragmentary, slightly younger remains from Kenya and nearby in the Middle Awash.
Until recently, remains of the diminutive Homo floresiensis had been found at a single locality only — in Liang Bua cave on the island of Flores in Indonesia.
prepared the manuscript, with contributions from other authors.
The find reveals that our forebears underwent a previously unknown stage of evolution more than a million years before Lucy, the iconic early human ancestor specimen that walked the Earth 3.2 million years ago.
Scientists today announced the discovery of the oldest fossil skeleton of a human ancestor.
Here we describe the age and context of the Mata Menge hominin specimens and associated archaeological findings.