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 .
dinosaur skeleton was discovered 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 skeleton of an early human ever found .