An unknown scale: Radiocarbon and stable isotope analysis of keratinous pangolin scales

Abstract At least eight species of pangolins, or “scaley anteaters,” are extant today. All are classified as vulnerable, endangered or critically endangered, with the most significant threat coming from the illegal trade in pangolin scales. Radiocarbon analysis is now frequently used help monitor and understand the illegal trade of ivory and rhino horn, and to understand the biology and ecology of certain species. This paper aims to assess whether radiocarbon dating can be used in a similar manner to understand either the trade in keratinous pangolin scales and/or the ecology of these poorly known animals. Pangolin scales grow incrementally in a similar way to human fingernails, although it has been unclear how quickly they grow, whether they fall out and regrow, and if/how they wear down over time. Using a collection of scales from animals accessioned to the Australian Museum in the 1970s/1980s ( Manis pentadactyla and Manis javanica ) and a collection of scale clippings from live Manis culionensis from Palawan, this study suggests that scales grow continuously and the proximal apex wears down over time. Whilst radiocarbon dates from scales of some animals appear to accurately reflect the age of death/capture, this is not always the case. This is likely to be because some animals consume more wood-eating termites, introducing substantial amounts of old carbon. We propose that radiocarbon may best be used as a dietary isotope, aiding in the understanding of the diversity of pangolin diet.