Computed Tomography as a Method for Age Determination of Carnivora and Odontocetes with Validation from Individuals with Known Age

Sina Baier-Stegmaier; Carsten Gundlach; Mariann Chriél; Mette Sif Hansen; Christina Vedel-Smith; Charlotte Vikkelsø Hansen; Daniel Klingberg Johansson; Louise Birgitte Henriksen; Magnus Wahlberg; Charlotte Bie Thøstesen; Aage Kristian Olsen Alstrup; Kristian Murphy Gregersen; Cino Pertoldi; Sussie Pagh

doi:10.3390/ani13111783

Computed Tomography as a Method for Age Determination of Carnivora and Odontocetes with Validation from Individuals with Known Age

Animals (Basel). 2023 May 27;13(11):1783. doi: 10.3390/ani13111783.

Authors

Sina Baier-Stegmaier¹, Carsten Gundlach¹, Mariann Chriél², Mette Sif Hansen^{2

3}, Christina Vedel-Smith⁴, Charlotte Vikkelsø Hansen⁴, Daniel Klingberg Johansson⁵, Louise Birgitte Henriksen⁶, Magnus Wahlberg⁷, Charlotte Bie Thøstesen⁸, Aage Kristian Olsen Alstrup^{9

10}, Kristian Murphy Gregersen¹¹, Cino Pertoldi¹², Sussie Pagh¹²

Affiliations

¹ Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
² Department of Health Technology Center for Diagnostics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
³ Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark.
⁴ Department of Research and Collections, Natural History Museum Aarhus, 8000 Aarhus, Denmark.
⁵ Natural History Museum of Denmark, University of Copenhagen, 1165 København, Denmark.
⁶ Department of Biology, University of Southern Denmark, 5230 Odense, Denmark.
⁷ Marine Biological Research Center, University of Southern Denmark, 5300 Kerteminde, Denmark.
⁸ The Fisheries and Maritime Museum, 6710 Esbjerg, Denmark.
⁹ Department of Clinical Medicine, Aarhus University, 8200 Aarhus, Denmark.
¹⁰ Department for Nuclear Medicine & PET, Aarhus University Hospital, 8200 Aarhus, Denmark.
¹¹ Institute of Conservation, Royal Danish Academy, 1435 København, Denmark.
¹² Department of Chemistry and Bioscience-Section of Biology and Environmental Science, Aalborg University, 9220 Aalborg, Denmark.

Abstract

Traditional methods for age determination of wildlife include either slicing thin sections off or grinding a tooth, both of which are laborious and invasive. Especially when it comes to ancient and valuable museum samples of rare or extinct species, non-invasive methods are preferable. In this study, X-ray micro-computed tomography (µ-CT) was verified as an alternative non-invasive method for age determination of three species within the order of Carnivora and suborders Odontoceti. Teeth from 13 red foxes (Vulpes vulpes), 2 American mink (Neogale vison), and 2 harbor porpoises (Phocoena phocoena) of known age were studied using µ-CT. The number of visible dental growth layers in the µ-CT were highly correlated with true age for all three species (R² = 96%, p < 0.001). In addition, the Bland-Altman plot showed high agreement between the age of individuals and visible dental layers represented in 2D slices of the 3D µ-CT images. The true age of individuals was on average 0.3 (±0.6 SD) years higher than the age interpreted by the µ-CT image, and there was a 95% agreement between the true age and the age interpreted from visible dental layers in the µ-CT.

Keywords: American mink; Neogale vison; Phocoena phocoena; Vulpes vulpes; X-ray; carnivore age; computed tomography; harbor porpoise; micro-CT; museum collections; red fox; toothed whale age; µ-CT.

Grants and funding

We acknowledge support from the Danish National Facility for Imaging with X-rays (DANFIX) funded by the Danish Agency for Science and Higher Education via grant ID 5072-00030B. S.B.S. is grateful for the financial support from Innovation Fund Denmark via grant 5152-00005B.