Scientists use CT technology to virtually reconstruct Hadropithecus skull

Fossils recovered in a remote cave in the Southeast corner of Madagascar by William L. Jungers, Ph.D., a paleoanthropologist at Stony Brook University Medical Centre, and his colleagues in Hawaii, Oregon, Massachusetts and Madagascar have been reuinted and reconstructed via computed tomography (CT) technology by collaborators at Pennsylvania State University. The team used CT scanning and computerisation to virtually glue newly discovered skull fragments of a rare extinct lemur found in 2003 back into its partial skull, originally discovered in 1899 and housed in Vienna, Austria. An article describing the work will be published in the early edition of the Proceedings of the National Academy of Sciences during the week of 28 July 2008.

The result of the digital manipulation is a nearly complete skull of Hadropithecus stenognathus, which is one of only two known skulls for this extinct lemur. To date scientists have known little about this giant lemur, the size of a large baboon, because few of its fossil remains have been found until recently by Dr Jungers and colleagues. The first specimens, partial skull pieces, found by fossil collector Franz Sikora in Madagascar in 1899 and the early 1900s are in Vienna. The modern finds of frontal skull bone pieces remain in the United States.

'Hadropithecus stenognathus is a poorly known and enigmatic 'monkey lemur' that went extinct in the recent past, but this new virtual restoration offers a fascinating glimpse into the brain and skull of what appears to be one of the most advanced giant lemurs,' said Dr Jungers.

'From the moment we combined the two datasets, it was obvious that the fossils belonged to the same individual,' said Timothy Ryan, Ph.D., anthropologist and lead author of the PNAS paper, titled 'A reconstruction of the Vienna skull of Hadropithecus stenognathus.'

'Because the newly discovered fragments fit into the skull so cleanly, we decided to attempt a more thorough virtual reconstruction,' said Dr Ryan. 'All the work was with the help of computers and neither all the scientists nor all of the specimens were ever in the same room.'

The end result was a beautiful image and three-dimensional print of the skull of the extinct lemur species that opened doors to new findings. For the first time, its cranial capacity (115 ml.) has been measured accurately. The team could also estimate its body size reliably from limb bones, as well as figure out accurate brain measurements. Hadropithecus not only had one of the largest brains relative to its body size of any known prosimian (a group of lemurs, lorises, and other similar animals), it also had a brain as large as that of some large monkeys.

Other members of the research team included D.A. Burney, National Tropical Botanical Garden, Kaleheo, Hawaii; L.R. Godfrey, University of Massachusetts; U.B. Gohlich, National History Museum of Vienna; N.Vasey, Portland State University, Portland, Oregon; Ramilisonia, Musee d'Art Archeologie, in Madagascar; A. Walker, Pennsylvania State University, and G.W. Weber, University of Vienna.

The research was supported by the National Science Foundation, the European Union, and Penn State and Portland State Universities.