A three-million-year-old child's skull discovered in South Africa has no signs of the type of soft spot that would be seen in human children with bigger brains.

The recent study projected that the Taung child skull displays the initial signs of cranial adaptation in a hominin called as Australopithecus Africanus, which lived about 2.1 to 3.3 million years ago.

The findings, published in the Proceedings of the National Academy of Science, are the newest contribution to long-running debate over whether the Taung child fossil may have shown the earliest signs of a fusing skull. Today babies are born with a number of plates in their skull that are loosely connected, forming soft spots that finally come together.

"A recent study has described the fossil as having a persistent metopic suture and open anterior fontanelle, two features that facilitate post-natal brain growth in human infants when their disappearance is delayed", says Dr. Kristian J Carlson of the University of Witwatersrand.

For the study, Carlson and colleagues from Columbia University and Florida Atlantic University made use of high-resolution computed tomography to see at each layer of the skull.

No evidence was found that early Hominin's infant brain growth was like modern humans.

The hypothesis that the features evolved in A. Africanus or early Homo Hominins is not supported by the results and with comparisons with the hominin fossil record and chimpanzee variation.

The latest scans have shown more details about the edges of what some scientists have supposed were skull plates.

According to researchers it is important to note that an open soft spot would be extraordinarily rare if the child was three or four years old and the fossil was beyond the age at which that would usually close in between three and nine months in modern babies.