New Scientist reports on a presentation at the Paleoanthropology Society meeting, in which Marc Meyer and Scott Williams describe one of the vertebral elements attributed to A.L. 288-1, the famous “Lucy” skeleton, as the vertebra of a gelada: “Baboon bone found in famous Lucy skeleton”.
One possible explanation was that the vertebra fragment came from a second, juvenile member of Lucy's species. So Williams and Meyer did a comparative study that included vertebrae from other Australopithecus fossils. To satisfy a personal hunch, Williams also added vertebrae from other animals known to have lived in the Hadar region 3.2 million years ago, such as porcupines and pigs. The results showed, surprisingly, that the fragment may not have belonged to Australopithecus at all.
"Baboons were a close match, both in shape and size," says Williams. "So we think we've solved this mystery. It seems that a fossil gelada baboon thoracic vertebra washed or was otherwise transported in the mix of Lucy's remains."
Mistakes in field identification of fossil remains are inevitable. It is rare for such misidentifications to persist for long under laboratory analysis, although it has happened with fossil hominins before. Most notably, the initial publications of the OH 7 type specimen of Homo habilis included a few bones amid the hominin hand remains, which were later identified as belonging to a large fossil monkey. Subtle anatomical mismatches, like a vertebra that is slightly wrong, require some detailed analysis to discover.
One thing that helps is greater access: As more and more specialists come to study fossil hominins, they bring a breadth of experience with different species and anatomical elements that no single expert can match.