La Trobe

Isotopic variation within Tasmanian bare-nosed wombat tooth enamel: Implications for archaeological and palaeoecological research

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posted on 2025-01-30, 05:40 authored by Georgia RobertsGeorgia Roberts, Jacqueline Towers, Michael Gagan, Richard CosgroveRichard Cosgrove, Colin SmithColin Smith
Archaeologists and palaeoecologists are increasingly turning to stable isotope analysis (δ 13 C, δ 18 O) of fossil bioapatite to examine interactions of human and animal populations. However, relatively few investigations have focussed on the identification of natural variation in comparable modern populations, particularly within the Australian context. In this paper, we present the first modern isotopic reference dataset for Tasmanian bare-nosed wombat teeth (Vombatus ursinus tasmaniensis). Samples for δ 13 C bioapatite and δ 18 O bioapatite measurements were recovered sequentially at sub-monthly resolution from all tooth types. δ 13 C bioapatite showed little variation within a seasonal sinusoidal pattern within the sample set (n = 24 wombats; 35 teeth) due to the homogeneous C 3 distribution of plants in Tasmania. In contrast, δ 18 O bioapatite profiles varied seasonally, representing time periods of between 0.9 and 2.1 years in 95% of the sample. Significant differences between tooth types were found from intra-individual to inter-regional scales for both dental growth rates and isotopic values. The accuracy of season-of-death assessments differed across the island; those in eastern Tasmania were accurate in all instances whereas those in the west showed substantial inaccuracies. We suggest that this may be due to the elodont form of wombat dentition and the ecologically influenced seasonally varied diet in western Tasmania. As the rate of dental growth is positively correlated with the proportion of coarse vegetation within the diet, this seasonal variation is therefore likely to change how annual isotopic signals are incorporated into the enamel. These results highlight the need to understand the degree of species-specific isotopic variation at a range of scales before applying this technique to archaeological or palaeontological assemblages.

Funding

This work was supported by La Trobe University (FHUSS Internal Research Grant Scheme – grant #2013-2-HDR-9); the Australian Geographic Society (2014); the Linnean Society of NSW (Joyce W. Vickery Scientific Research Fund 2014); and the Australian Archaeological Association (Student Research Grant Scheme 2014). GLR acknowledges an Australian Postgraduate Award. CS acknowledges an ARC Future Fellowship (FT0992258).

History

Publication Date

2019-06-01

Journal

Palaeogeography, Palaeoclimatology, Palaeoecology

Volume

523

Pagination

19p. (p. 97-115)

Publisher

Elsevier

ISSN

0031-0182

Rights Statement

© 2019 Crown. Published by Elsevier B.V. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

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