What's my age again? On the ambiguity of histology-based skeletochronology

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 288; no. 1955; p. 20211166
• Main Authors: Schucht, Pia J, Klein, Nicole, Lambertz, Markus
• Format: Journal Article
• Language: English
• Published: England The Royal Society 28.07.2021
• Subjects: Animals; Bone and Bones; Bone Development; Morphology and Biomechanics; Reproducibility of Results; age determination; bone histology; skeletochronology; life history
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.2021.1166

Histology-based skeletochronology is a widely used approach to determine the age of an individual, and is based on the assumption that temporal cessations or decelerations of bone growth lead to incremental growth marks (GM), reflecting annual cycles. We studied the reliability of histology-based skeletochronology in a variety of extant tetrapods by comparing two different approaches: petrographic ground sections versus stained microtomized sections. Each bone was cut into two corresponding halves at its growth centre in order to apply both approaches to one and the same sample. None of the samples unequivocally revealed the actual age of the specimens, but truly concerning is the fact that the majority of samples even led to conflicting age estimates between the two approaches. Although the microtomized sections tended to yield more GM and thus indicated an older age than the ground sections, the contrary also occurred. Such a pronounced ambiguity in skeletochronological data strongly challenges the value of the respective age determinations for both extant and extinct animals. We conclude that much more research on the fundamental methodological side of skeletochronology-especially regarding the general nature and microscopic recognition of GM-is required.