Structural density of the leopard tortoise (Stigmochelys pardalis) shell and its implications for taphonomic research

Sharon Holt, Liora Kolska Horwitz, Jakobus Hoffman, Daryl Codron

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

We investigated bone mineral density values of the shell (carapace and plastron) of a modern leopard tortoise (Stigmochelys pardalis Bell, 1828) to assess its impact on survivorship of the different skeletal elements. We found significant differences among elements for bone mineral density and density volume, but not for bone mineral content. We then compared these findings with those obtained using computed tomography (CT) scans of shells of three modern tortoise species that differ in size and shape; the leopard tortoise, greater padloper (Homopus femoralis) and angulate tortoise (Chersina angulata). Results indicate that the patterning of bone density is similar across shell elements and scan sites in all species, although all values were lower in the greater padloper, which we attributed to shape differences – a flat rather than domed shell. Finally, we correlated the frequency of shell elements from the Holocene leopard tortoises recovered at the site of Wonderwerk Cave (South Africa) using, as a proxy, the densitometry values obtained from the modern leopard tortoise. For most strata there was a significant association with skeletal element survivorship demonstrating the role played by bone mineral density in determining the skeletal composition of this assemblage.

Original languageEnglish
Article number101819
JournalJournal of Archaeological Science: Reports
Volume26
DOIs
StatePublished - Aug 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd

Funding

This work was supported by a grant from the Palaeontological Scientific Trust (PAST) towards SH's PhD research; Special thanks to: the Centre of Excellence for Nutrition at the North West University for permission to undertake the bone density scans and Magda Uys who undertook the scanning; David Morris (Department of Archaeology, McGregor Museum, Kimberley) for permission to study the Wonderwerk Cave fauna; Michael Chazan (co-director of the Wonderwerk Cave project) for his ongoing and generous support of this research; Beryl Wilson (Department of Zoology, McGregor Museum, Kimberley) who collected the modern leopard tortoise used in this study and for the loan of the greater padloper specimen analysed here; The National Museum, Bloemfontein that facilitated aspects of this research; Rian Horn who photographed the tortoise skeletal elements. We thank the two anonymous reviewers for their insightful comments which helped to improve this paper.

FundersFunder number
Department of Archaeology
National Museum
North West University
Palaeontological Scientific Trust

    Keywords

    • Bone mineral density
    • CT scanning
    • Densitometry
    • Leopard tortoise
    • Taphonomy
    • Wonderwerk Cave

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