Aplicación del Synchrotron X-Ray Tomographic Microscopy al estudio funcional del aparato conodontal

Abstract

Conodonts were eel-shaped soft-bodied organisms, which unique hard-parts were a set of teeth-like elements placed in their oral cavity. Among the different controversies around the group, their biological affinities and the function of those mineralised elements focus most of the attention of the conodont workers. Until recent, conodont functional analysis has been limited to analogy and qualitative analytical approaches, but more recently, novel quantitative computational methods, such as computed tomography, are opening new opportunities to study the function of these elements. Following this, the objective of the present work is to study the function of various taxa belonging to the Epigondolella-Mockina linage from the Upper Triassic of Italy using Synchrotron X-Ray Tomographic Microscopy (SXRTM). Our functional analysis was centred on the development of their occlusal cycle based on the 3D models (digital and physical) obtained from several P1 clusters scanned with the SXRTM, and corroborated by microwear analyses in single specimens of the same taxa. Our results show a bilateral occlusal cycle with an orthogonal approach, model corroborated by the presence of microwear on the predicted functional surfaces. Interestingly, the tomographic study of the inner microstructures has allowed us to identify the same external wear pattern internally, providing strong support of damage regeneration. This damage repair has been identified as well in other related taxa suggesting that this internal damage is not a taphonomical artefact. Therefore, our results allow us to conclude that the P1 elements of several taxa belonging to the Epigondolella-Mockina linage where indeed used as teeth; and more interesting, that they were retained through the whole life of these animals and not shed and replaced as it has been proposed before.