Island rule and bone metabolism in fossil murines from Timor

Miszkiewicz, JJ; Louys, J; Beck, RMD; Mahoney, P; Aplin, K; O’Connor, S

Abstract

Skeletal growth rates reconstructed from bone histology in extinct insular hippopotamids, elephants, bovids and
sauropods have been used to infer dwarfism as a response to island conditions. Limited published records of osteocyte
lacunae densities (Ot.Dn), a proxy for living osteocyte proliferation, have suggested a slower rate of bone metabolism
in giant mammals. Here, we test whether insularity might have affected bone metabolism in a series of small
to giant murine rodents from Timor. Ten adult femora were selected from a fossil assemblage dated to the Late
Quaternary (~5000–18 000 years old). Femur morphometric data were used in computing phylogenetically informed
body mass regressions, although the phylogenetic signal was very low (Pagel’s λ = 0.03). Estimates of body weight
calculated from these femora ranged from 75 to 1188 g. Osteocyte lacunae densities from histological sections of the
midshaft femur were evaluated against bone size and estimated body weight. Statistically significant (P < 0.05) and
strongly negative relationships between Ot.Dn, femur size and estimated weight were found. Larger specimens were
characterized by lower Ot.Dn, indicating that giant murines from Timor might have had a relatively slow pace of
bone metabolic activity, consistent with predictions made by the island rule.

Citation

Miszkiewicz, J., Louys, J., Beck, R., Mahoney, P., Aplin, K., & O’Connor, S. (2020). Island rule and bone metabolism in fossil murines from Timor. Biological Journal of the Linnean Society, 129(3), 570-586. https://doi.org/10.1093/biolinnean/blz197

• Journal Article Type: Article
• Acceptance Date: Dec 12, 2019
• Online Publication Date: Jan 18, 2020
• Publication Date: Mar 1, 2020
• Deposit Date: Jan 20, 2020
• Publicly Available Date: Jan 18, 2021
• Journal: Biological Journal of the Linnean Society
• Print ISSN: 0024-4066
• Electronic ISSN: 1095-8312
• Publisher: Oxford University Press
• Volume: 129
• Issue: 3
• Pages: 570-586
• DOI: https://doi.org/10.1093/biolinnean/blz197
• Publisher URL: https://doi.org/10.1093/biolinnean/blz197
• Related Public URLs: https://academic.oup.com/biolinnean