First studies of fossil of new human ancestor take place at the ESRF

Prof. Lee Berger of the University of the Witwatersrand (South Africa) has discovered a new species of early human ancestor. The fossil’s extraordinary state of preservation encouraged scientists to exploit a non-destructive tool called X-ray synchrotron microtomography, which has revolutionised palaeontology and palaeoanthropology in the last decade. Preliminary, not-yet-published results show the presence of what could be fossilised insect eggs and hints of a potential brain remnant of the hominid.

The use of X-ray synchrotron microtomography for studying fossils has been developed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, by Paul Tafforeau. The ESRF synchrotron light enables scientists to visualise the inside of a fossil block, sometimes up to the micron scale, without breaking it open, with contrast, sensitivity and resolution far above those of conventional X-ray machines.

The skull of Australopithecus sediba at ESRF beamline ID19, where the skull’s teeth were investigated. The transparent plastic tube provided a stable support during the movements of the table at the scans. Credits:I. Montero.	Lee Berger inspects virtual slice through the skull, from a set of many thousand such frames, on a large screen in the control hutch of beamline ID17. Credits:I. Montero.	A vertebra of the backbone of Australopithecus sediba ready for scan at sub-micron resolution. Credits:I. Montero.

Prof. Lee Berger teamed up with Paul Tafforeau and took the fossil to the ESRF in February 2010 for an extensive two-week long investigation. In addition to the skull, many fragments of the skeleton, representing nearly forty percent of an entire body, were also analysed.

They also analysed in detail the teeth of the fossil. Studying their internal growth lines and structure to the daily level could provide the age at death of the individual. By comparing his real age and his developmental level, scientists would gain insights about his life history 1.9 million years ago.

Prof. Lee Berger pushed the investigation further by using the ESRF to look at possible remnants of soft parts of the body that normally do not fossilise, such as brain tissue. He did not carve out entirely the stone matrix from the skull, a procedure carried out for all other hominid skulls in the past to prepare for examination. The X-rays delved deep into the rock to find any fossilised traces of what had been there 1.9 million years ago.

3D reconstruction of the A. Sediba's skull carried out at the ESRF. Credits: P. Tafforeau.

The analysis of the data has only just started, but the preliminary visualisation of the complete skull already available shows fossilised insect eggs whose larvae could have fed on the flesh of the hominid after death. Researchers also noticed an extended low density area that could point towards a remnant of the brain after its bacterial decay.
 
It is only the second time ever that a complete skull of a hominid is examined using powerful synchrotron radiation. This kind of analysis is currently only possible at the ESRF.

Wits University is the curator of the fossils which belong to the people of South Africa.

Top image: Rendering of the 3-D scan of the skull of Australopithecus sediba child. Credits: P. Tafforeau