X-ray microtomography applied to fossils preserved in compression: Palaeoscolescid worms from the Lower Ordovician Fezouata Shale

Abstract

Computed microtomography (XR-μCT) was used to study the three-dimensional morphology of Palaeoscolex cf. tenensis, a palaeoscolecid worm from the Lower Ordovician Fezouata Lagerstätte (Central Anti-Atlas, Morocco). This method revealed important aspects of its internal anatomy such as a pharynx bearing longitudinal rows of tiny teeth. Tubular structures are interpreted as the fragments of a cylindrical gut tract running from mouth to anus. Energy Dispersive X-ray Analysis (EDX) confirm the primary phosphatic composition of the microplates associated with the cuticle of the worm and suggests that the preservation of soft tissues took place via early bacteria-mediated pyritization followed by strong weathering of Fe-rich aluminosilicates during diagenesis.