Trace fossils on a trace fossil: A vertebrate-bitten vertebrate coprolite from the miocene of Italy

Despite their long history of discoveries and research, of all the vertebrate coprolites currently known worldwide, only a very few have been explicitly recognised as exhibiting bite marks by other vertebrates. These rare specimens represent “compound ichnofossils”, i.e., trace fossils (the lithifie faeces) on which other trace fossils (the tooth incisions) are present. Here we report on an unusual large-sized coprolite from the Miocene “Pietra leccese” formation of southern Italy that displays several superficia bite marks. This specimen is described, f gured, and chemically characterised by means of hand-held energy dispersive X-ray f uorescence – the firs application of this method to the analysis of a vertebrate coprolite. Based on its size, morphology, structure, and major-element composition, the Pietra leccese coprolite is here identifie as the fossilised excreta of a large carnivorous vertebrate, possibly a shark, whereas the tooth incisions are attributed to the biting action of indeterminate f sh, likely including both bony and cartilaginous fish Biting seemingly occurred prior to the eventual deposition of the scat at the seafl or (i.e., when it was still in the water column) and probably ref ects unintentional snagging or aborted exploratory coprophagy aimed at testing the palatability of the faeces. In conclusion, the highly idiosyncratic specimen described in this paper represents a significa t addition to the overly scanty record of vertebrate-bitten vertebrate coprolites and provides an unusual window on the ecological interactions between marine vertebrates in the Miocene central Mediterranean ecosystems witnessed by the remarkable fossil assemblage of the Pietra leccese.