This repository contains data and code to replicate the monte-carlo changepoint analysis performed in Lindscott and Wallace et al. (2026), Bomb radiocarbon reveals keratin growth dynamics in loggerhead (Caretta caretta) and green (Chelonia mydas) turtles, published in Marine Biology. Please cite that paper if you use this code.

Changepoint analysis was used to empirically identify shifts in the growth rates of the analysed turtle scute records, whilst accounting for the age uncertainty inherent to the radiocarbon dating used to develop the age models. Stacked probability density functions of the changepoints across multiple individuals were used to identify periods of widespread change across the sampled population.

To use this repository, follow the steps below. For any comments/questions/issues, contact Matt at [email protected]. This guide assumes you have (1) R and Rstudio installed, and (2) a basic understanding of how R and R packages work.

1. Download this repository and unzip it to somewhere that makes sense on your machine.

2. Open the .Rproj file. It should launch into a blank workspace in Rstudio.

3. Open ‘CPT-analysis-script.R’ under /scripts-and-documents/

4. Follow the instructions therein.

5. For more exploratory analysis and method development, open the ‘Turtle-scute-writeup.Rmd’ notebook. It should render to a word document, assuming you have ms office installed.

Note: This repository relies on a helper R package, turtleCPTs, for most of the underlying functions. If you want to get ‘under the hood’ and pick apart the underlying code, you’ll probably need to head over to that repository and pick apart the functions therein.