Lucy, the oldest and most complete fossil of an early human ever found, still has a few secrets to reveal. Discovered in 1974, the 3.2 million-year-old skeleton stunned archaeologists who unearthed the fossil while digging in an isolated spot in the Afar region of Ethiopia. Now, a new look at the ancient hominin's skeleton suggests one of the bones may, in fact, belong to a baboon. Lucy, the oldest and most complete fossil of an early human ever found, still has a few secrets to reveal. A new look at the ancient hominin's skeleton suggests one of the vertebrae bones may belong to a baboon . Despite being uncovered 40 years ago, Lucy is still being studied to learn more about our ancestors. The skeleton belongs to a species called Australopithecus afarensis and is around 40 per cent complete. When discovered in Ethiopia, Lucy was the only skeleton of the species known; she would've stood 3.5 feet (about a meter) tall. Currently, more than 300 individuals of this species, which lived between about 3.85 million and 2.95 million years ago, have been uncovered . The strange discovery of a baboon bone was made when Gary Sawyer and Mike Smith at the American Museum of Natural History in New York began work on a reconstruction of Lucy's skeleton (right) The strange discovery of a baboon bone was made when Gary Sawyer and Mike Smith at the American Museum of Natural History in New York began work on a reconstruction of Lucy's skeleton. 'Mike pointed out that one of the [vertebra] fragments, which no one, including me, had really paid close attention to, looked fairly small to fit with the rest of Lucy's vertebral column,' Scott Williams at New York University told the New Scientist. The researchers thought one possible explanation was that the fragment was missed up with another, younger member of Lucy's species. A comparative study of vertebrae from other Australopithecus fossils in that region disproved this theory. The researchers analysed 11 rock samples from around the nearly complete Little Foot fossil skeleton from theSterkfontein Caves to gauge its age . Scientists have revealed a sophisticated new dating . technique shows that Little Foot, an important fossil of an . early human forerunner unearthed in the 1990s in South Africa, . is roughly 3.7 million years old. 'The age of Little Foot has been highly debated,' said . geologist Darryl Granger of Purdue University in Indiana, whose . research appears in the journal Nature. The study found Little Foot, a member of the species . Australopithecus prometheus, lived at roughly the same time as . Australopithecus afarensis, the species whose most famous . fossil, known as Lucy, comes from Ethiopia. Both species blended ape-like and human-like traits but with different features. The researchers analysed 11 rock samples from around the . nearly complete Little Foot fossil skeleton from the . Sterkfontein Caves to gauge its age. The findings may have important implications about the . evolutionary relationships among humankind's ancient relatives. The team then compared it to the vertebrae of other creatures living in that region 3.2 million years ago, and found a baboon bone was the closest fit. Williams told New Scientist that the fossil of a gelada baboon thoracic vertebra must have somehow been mixed up with Lucy's remains. The team now plan to present their findings at the Paleoanthropology Society in San Francisco next week. Our species, Homo sapiens, appeared roughly 200,000 years . ago. Earlier members of the human genus, Homo, date back more . than 2 million years. Our genus was predated by other species on . the human family tree including various representatives of Lucy's genus Australopithecus. Dr Simon Underdown, principal lecturer in anthropology at Oxford Brookes University, said: 'The co-mingling of skeletons is quite common in the archaeological record and it can often be difficult to separate out different elements if multiple bodies are mixed together. 'Lucy was not found in association with lots of other different bones and was painstakingly studied during excavation and description. Mistakes can of course be made with 1000s of fragments but that wasn’t the case here. 'Even if one fragment of a bone from the spine turns out to be from a baboon it does not alter the larger picture of what Lucy brings to the story of human evolution.' Our genus was predated by other species on . the human family tree including various representatives of the . genus Australopithecus, of which Lucy (reconstruction pictured) belonged to .
Baboon bone was spotted by the American Museum of Natural History .
Researchers thought one of the vertebra bones was too small to fit Lucy .
They say the baboon bone was somehow mixed up with Lucy's remains .
Lucy is oldest and most complete fossil of an early human ever found .