Bone histology in a fossil elephant (Elephas maximus) from Pulau Bangka, Indonesia

ABSTRACT

Analyses of Pleistocene fossil proboscideans have long been used as indirect evidence for climactic and environmental shifts in the Sunda shelf of Southeast Asia. Reconstructing the biological effects of rainforest expansion at the Last Glacial Maximum on elephants can be enhanced by a better understanding of fossil proboscidean palaeobiology. We studied fragmented post-cranial fossil remains of an Asian elephant (Elephas maximus) from Pulau Bangka, an island to the east of Sumatra, hypothesised to be within the Late Pleistocene Sundaland savannah corridor. Bone histology of the humerus, rib, and vertebrae from the Bangka fossil were examined and compared with modern conspecifics to reconstruct remodelling. We measured secondary osteon population density, osteon area, diameter, and infill ratios in Haversian bone. Intra-skeletally, we found that the histology of the largely weight-bearing humerus indicated slower remodelling than that of the ribs and vertebrae, which are less biomechanically constrained. Inter-skeletally, the fossil rib histology showed relatively smaller osteons and Haversian canals when compared to the modern samples. Differences in lifestyles, including range-expansion, may have influenced micro-morphometric differences in elephant rib histology. Our results contribute indirect evidence of the effects of climactic variability in the Sunda palaeoenvironment on Pleistocene fauna.

KEYWORDS:

• Haversian system
• mammalian histology
• Pleistocene elephant
• Proboscidea
• Sunda palaeoenvironment

Acknowledgments

Permission for the research was granted by the Indonesian government – RISTEK Foreign Research Permit (Louys 2483/FRP/E5/Dit.KI/V/2018). The authors would like to thank Gerrit van den Bergh for comments on an earlier draft, David McGregor for technical support, and two anonymous reviewers for their constructive suggestions.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and/or its supplementary materials.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/08912963.2022.2092850

Additional information

Funding

Research and fieldwork were supported by an Australian Research Council Future Fellowship to JL (FT160100450). Laboratory facilities at the Australian National University (ANU) are funded by the Australian Research Council to JM (DE190100068) and the ANU College of Arts and Social Sciences. PB is funded through the Griffith University International Postgraduate Research Scholarship.