Identifying Ranid urostyle, ilial and anomolous bones from a 15th century London well

The accurate identification of bones from archaeological excavations is critical for the understanding of past faunas. In the United Kingdom, remains from East Anglian fens suggest that more anuran species existed in Saxon times than is the case today. Here, novel methods have been devised to determine the identity of anuran ilia and urostyle bones. These methods were used on remains from a 15th century archaeological site 200 metres north of St Paul's Cathedral, London, originally assumed to be common frog (Rana temporaria) with one possible water frog (Pelophylax sp.) imported as human food. The results suggest that the majority of the ca. 500 year old urostyle remains can be attributed to (in order of likelihood) P. lessonae, R. arvalis or R. dalmatina. The approaches described here complement existing methods and allow for more robust future identifications from zooarchaeological remains. A method is also suggested for taking the effect of growth on different parts of the same bone into account, thereby making bones of various sizes more comparable.