From BBC News:
Fossil hunters have found remains of a probable direct ancestor of humans that lived more than four million years ago. The specimens of this ancient creature are helping bridge a long gap during a crucial phase of human evolution. Professor Tim White of the University of California, Berkeley, and colleagues unearthed the cache of fossils in the Middle Awash region of Ethiopia. They describe the finds, which belong to the species Australopithecus anamensis, in the journal Nature.
Our own genus, Homo, is widely thought to have evolved from this group. So the relationship of Australopithecus to even earlier bipedal hominids is crucial to understanding where we all ultimately come from. When placed together with other fossils from the same general area of Ethiopia, the 4.1-million-year-old anamensis specimens appear to establish an evolutionary succession between earlier and later species. “The fact anamensis is sandwiched between earlier and later hominids is what is really significant about this Ethiopian sequence,” Tim White told the BBC News website.
More here.