Enamel thickness in South African australopithecines: noninvasive evaluation by computed tomography

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dc.contributor.authorConroy, Glenn C
dc.date.accessioned2015-01-06T07:18:45Z
dc.date.available2015-01-06T07:18:45Z
dc.date.issued1991
dc.description.abstractUntil recently, it has not been possible to systematically study enamel thickness in fossil hominids except by physically sectioning the teeth. Because sectioning studies destroy original specimens, sample sizes will always be low. For this reason, anthropologists have had to devise other methods for acquiring these data such as by measuring enamel in naturally fractured teeth or where it is exposed in worn teeth. It is clearly important to develop and apply non-invasive techniques to augment and expand the data base of early hominid enamel thickness. This is a first attempt to provide such data for a sample of South African australopithecines by utilizing high-resolution computed tomography (CT). This study is based on over 130 CT scans taken at 1 mm slice thickness on a sample of 22 original Australopithecus africanus and A. robustus lower molars from Sterkfontein, Kromdraai, Makapansgat, Swartkrans and Taung. Mean values of absolute and relative enamel thickness between A. africanus and A. robustus are significantly different, confirming that robust australopithecines have thicker enamel than their gracile counterparts. CT sections were taken in the buccolingual plane through the mesial cusps (protoconid, metaconid). While the mean value of enamel thickness at the buccal cusp (protoconid) is greater in A. robustus than in A. africanus, the difference is not statistically significant. The difference in enamel thickness at the lingual cusp (metaconid) is statistically significant, however. This study represents an important, albeit preliminary, first step in establishing a methodology for the non-invasive evaluation of enamel thickness in fossil hominids by computed tomography. It demonstrates the viability of the technique and the type of problem oriented approach that can be tackled using computed tomography in modem anthropological research. Measurements derived from CT cannot, of course, be expected to have the same degree of precision as those taken directly from sectioned teeth; nevertheless, important insights into the functional morphology of early hominid teeth are still easily decipherable from the CT data. Given that the alternative to CT is the physical destruction of original hominid fossils, the slight loss in mensurational accuracy seems well worth the price.en_ZA
dc.description.sponsorshipNational Science Foundationen_ZA
dc.identifier.issn0078-8554
dc.identifier.urihttp://hdl.handle.net/10539/16163
dc.language.isoenen_ZA
dc.publisherBERNARD PRICE INSTITUTE FOR PALAEONTOLOGICAL RESEARCHen_ZA
dc.subjectenamel-dentin junctionen_ZA
dc.subjectnon-invasiveen_ZA
dc.subjectAustralopithecus africanusen_ZA
dc.subjectAustralopithecus robustusen_ZA
dc.titleEnamel thickness in South African australopithecines: noninvasive evaluation by computed tomographyen_ZA
dc.typeArticleen_ZA
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Volume 28 1991