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U.S. GEOLOGICAL SURVEY
Open-File Report 2008-1209

A Protocol for Aging Anurans Using Skeletochronology

By Brome McCreary, Christopher A. Pearl, and Michael J. Adams

Abstract

Age distribution information can be an important part of understanding the biology of any population. Age estimates collected from the annual growth rings found in tooth and bone cross sections, often referred to as Lines of Arrested Growth (LAGs), have been used in the study of various animals. In this manual, we describe in detail all necessary steps required to obtain estimates of age from anuran bone cross sections via skeletochronological assessment. We include comprehensive descriptions of how to fix and decalcify toe specimens (phalanges), process a phalange prior to embedding, embed the phalange in paraffin, section the phalange using a microtome, stain and mount the cross sections of the phalange and read the LAGs to obtain age estimates.

Contents

Abstract
Introduction
Fixation and Decalcification
Processing
Embedding
Facing and Sectioning
Staining
Mounting
Reading Sections
Acknowledgements
References
Appendix 1. Selected Literature Review of Key Steps in Skeletochronology Procedure
Appendix 2. List of Materials
Appendix 3. Chemical Replacement Schedules
Appendix 4. Definitions for the Sample Datasheet
Appendix 5. Definitions for the Sectioning Datasheet
Appendix 6. Processing by Contractor
Appendix 7. Definitions for the Aging Datasheet

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