Mark of ectoparasitic activity on a bothremydid (Pleurodira) turtle shell from the Lo Hueco site (Upper Cretaceous, Central Spain)

Abstract

Shell pitting is relatively abundant but with unclear character and etiology in extinct turtles, since reports on extant turtles with similar condition do not usually include morphological descriptions, illustrations, or data concerning etiology or pathogenesis. Therefore, the available interpretations on shell pitting in the fossil record of turtles are generally speculative or poorly justified. We analyze herein a mark identified in a partial carapace of a bothremydid turtle from the Upper Cretaceous (upper Campanian–lower Maastrichtian) fossil site of Lo Hueco (Cuenca, Central Spain). This mark has been analyzed both through physical examination and by the use of computerized axial tomography scan. The discussion has been established following a differential diagnosis procedure, a presumptive diagnosis was made on the basis of analogy and total or partial similarities with other cases previously documented both in extinct and extant turtle specimens. As a result, information regarding the possible etiology, pathogenesis, and stages of healing of the mark studied here are provided. An ectoparasitic origin is suggested as the most parsimonious hypothesis explaining its etiology, this mark being considered as a pathology. This study represents to the first report of a pathology of ectoparasitic origin in the shell of a bothremydid turtle.