Scientists in South Africa have unveiled what they believe is a previously unknown species of early human.
The partial skeletons of a juvenile male and adult female are thought to be 1.9 million years old and have shed further light on the evolution of humans.
The ABC reports they were found in a cave called Malapa in the Cradle of Humankind World Heritage Area.
Two papers published in the journal Science describe the fossils, which have been called Australopithecus sediba.
The skeletons were found close together in sediments dated between 1.78 and 1.95 million years old.
The first bone was picked up by the son of Professor Lee Berger from the University of Witwatersrand.
Matthew, aged nine, says he thought he had discovered an animal bone.
Fossils of at least 25 animals were also found in the cave, including large-toothed cats, a brown hyena, a wild dog, antelopes and a horse.
Dr Andy Herries of the University of New South Wales in Sydney says the new fossils add to an increasingly complicated picture on the evolution of humans (Homo sapiens).
Dr Herries says most scientists believe the genus Homo evolved from the genus Australopithecus and until now the most likely candidate was Australopithecus africanus.
He says Australopithecus sediba had a small brain like the primitive Australopithecus africanus, which died out around 2.1 million years ago.
But other features, especially its pelvis, are similar to Homo erectus which appeared around 1.8 million years ago.
"It would have walked in a very modern way," Dr Herries said.
He says the features of the new species are an intermediate between Australopithecus africanus and Homo erectus, suggesting it provides a link between them.