(CNN) -- Scientists in Spain announced Thursday that they've unearthed a 13 million-year-old fossilized skeleton of an ape that is possibly a common ancestor of humans and great apes, including orangutans, bonobos, chimps and gorillas.
The find could add a yet another branch to the human family tree and fill in a gap in our knowledge of hominoid evolution.
"It's very special," said Frans de Waal of the Yerkes Primate Center at Emory University in Atlanta. "It's almost as if we will have to redraw the (evolutionary) tree if these discoveries keep coming out."
Salvador Moya-Sola of the Miguel Crusafont Institute of Paleontology in Barcelona, Spain, and his colleagues describe the species, which they have named Pierolapithecus catalaunicus, in the November 19 issue of the journal Science.
"The importance of this new fossil is that for the first time all the key areas that define modern great apes are well-preserved," Moya-Sola said in a statement. Fossils of apes are extremely rare and do not fossilize well because they are often in forests, where bones tend to decay.
Yet de Waal cautioned against making conclusions about whether this new fossil is a route on the road to human evolution.
"It's spectacular to have new information on this," he said. "But (human evolution) is not a straight line, it's has an enormous number of side branches."
Researchers think great apes diverged from lesser apes, which are gibbons and siamangs, about 11 million to 16 million years ago. Fossils from that geological epoch, called the middle Miocene, are fairly rare. Scientists believe humans diverged from the living great apes about 6 million years ago.
The searchers say it could be that Pierolapithecus is not itself the last common ancestor of the great apes, but rather a close relative of that animal.
Study of the fossilized bones suggest Pierolapithecus was a tree climber, with a stiff lower spine, and a specially adapted rib cage and wrist bones. However, its short fingers suggest it did not do a lot of hanging from branches.
The bones were found near Barcelona after a bulldozer clearing land at a dig site turned up a tooth. Study of the fossils suggests the ape was male, weighed about 75 pounds, and ate fruit.
And while the bones were found in Spain, Moya-Sola suspects the species also lived in Africa.
Only four species of great apes -- orangutans, bonobos, gorillas and chimpanzees -- exist today. All of them are endangered due to hunting and habitat loss.
