South African scientists claimed Thursday to have uncovered the most complete skeleton yet of an ancient relative of man, hidden in a rock excavated from an archaeological site three years ago. The remains of a juvenile hominid skeleton, of the newly identified Australopithecus (southern ape) sediba species, are the \"most complete early human ancestor skeleton ever discovered,\" according to University of Witwatersrand paleontologist Lee Berger. \"We have discovered parts of a jaw and critical aspects of the body including what appear to be a complete femur (thigh bone), ribs, vertebrae and other important limb elements, some never before seen in such completeness in the human fossil record,\" said Berger, a lead professor in the finding. The latest discovery was made in a one-metre-wide rock that lay unnoticed for years in a laboratory until a technician incidentally saw a tooth sticking out of the black stone last month. It was then scanned to reveal significant parts of A.sediba, whose other parts were discovered in 2009 in the world-famous Cradle of Humankind north of Johannesburg. It is not certain whether the species, which had long arms, a small brain and a thumb, was a direct ancestor of humans\' genus, Homo, or simply a close relative. \"It appears that we now have some of the most critical and complete remains of the skeleton,\" said Berger. Other team members were equally enthusiastic. \"It\'s like putting together the pieces of a puzzle,\" university laboratory manager Bonita De Klerk told AFP. The skeleton is thought to be around two million years old and would have been aged between nine and 13 years when the upright-walking tree climber died. De Klerk said: \"It was in packing this (stone) up in the vehicle to go and be scanned that one of our technicians actually noticed a tooth sticking out on the surface and he called Lee over and said, \'Oh, I think this is a hominid tooth\', and he was right.\" The Cradle of Humankind, now a World Heritage Site, is the oldest continuous palaeontological dig in the world.