The cover of the November issue of National Geographic Magazine shows a reconstruction of the face of a three-year-old Australopithecus afarensis. The remains - no bigger than a cantaloupe - are 3.3 million years old, making them the oldest known skeleton of such a youthful human ancestor. ((AP Photo/National Geographic, JBALLAY))

A nearly intact skeleton of a three-year-old female human ancestor, the same species as the famed Lucy skeleton, has been found in Ethiopia.

The juvenile skeleton of Australopithecus afarensis will fill an important gap in the understanding of the species, thought to be an early human ancestor, said William Kimbel, a paleoanthropologist at Arizona State University.

Kimbel said a complete skeleton of Australopithecus is "extraordinarily rare."

"It's unprecedented to have such a complete skeleton of a young child," said Kimbel in a statement.

The skeleton was discovered in Dikika, Ethiopia, by Zeresenay Alemseged, a former postdoctoral researcher at Arizona State, now at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Kimbel was part of the team that studied the 3.3-million-year-old fossilized skeleton, which included scientists in the U.S., U.K. and France.

Their research is published in Thursday's issue of the journal Nature.

The remains include a skull and jaws, including teeth, and parts of the shoulders, spinal column, ribs, right arm, fingers, legs and left foot.

They also include a hyoid, a bone located in the voice-boxthat supports the muscles involved in speech. It is the first time the bone has been found this early in the homonin fossil record.

Fred Spoor of University College London said the fossil hyoid was more similar to bones found in apes than those found in humans.

In their analysis of the skeleton, Alemseged and his team said the skeleton's lower body is adapted for walking, but the upper body shows some gorilla-like qualities.

Some researchers say the ape-like shoulder blade shows that the species spent some time climbing trees, while others say the upper-body features are retained from an ancestor but aren't functional.

"The mix of features in this skeleton is going to stir up the debate about locomotion in early Australopithecus," Kimbel said in statement.