Rock containing ‘most complete early human skull ever’ discovered… It was on the shelf of a laboratory for three years!
By Ker Than
National Geographic News
Last month a prehistoric tooth protruding from a boulder tipped off researchers to hidden evolutionary treasure: remarkably complete human-ancestor fossils trapped in a rock that had been sitting in their lab for years.
Scans later showed that the rock contains two-million-year-old fossils that will “almost certainly” make one Australopithecus sediba specimen “the most complete early human ancestor skeleton ever discovered,” anthropologist Lee Berger said in a statement Thursday.
(See pictures of Australopithecus sediba fossils.)
The bones are nearly invisible from the outside, and were discovered only after a technician noticed the small tooth in the three-foot-wide (meter-wide) rock, which was retrieved from a South African cave in 2008 and brought to a lab at the University of the Witwatersrand in Johannesburg.
The tooth turned out to be just the tip of the fossil iceberg.
A CT scan revealed other bones inside, including parts of a jaw, a complete thigh bone, ribs, vertebrae, and possibly hand and foot bones.
“What we can see inside of the rock using state-of-the-art scanners,” Berger said, “are some of the most complete bones that we’ve ever discovered in early hominins”—human species and their close evolutionary ancestors.
Scientists think the fossils are the missing remains of “Karabo,” a partial A. sediba skeleton belonging to a male child that Berger’s team had previously unearthed.
“What we found inside of this enormous rock is what appears to be the remainder of either the skeleton of Karabo or another skeleton entirely,” Berger, of the University of the Witwatersrand in Johannesburg, told National Geographic News.
“The More Bones, the Better”
A. sediba is one of the newest additions to the list of early human ancestors and also one of the most enigmatic hominins ever discovered. (See “‘Key’ Human Ancestor Found: Fossils Link Apes, First Humans?”)
Studies have shown that the species possessed an unusual mix of primitive and or humanlike traits. For example, scientists think A. sediba could stand and walk upright but that it still spent some time in trees.
Additionally, the creature had a relatively large brain and surprisingly agile hands, suggesting the species may have been capable of crafting and using stone tools.
But there are still a lot of lingering questions about A. sediba and early hominins in general—questions that paleontologist Scott Simpson thinks the new bones could help resolve.