Morphology and ecological setting of the basal echinoid genus Rhenechinus from the early Devonian of Spain and Germany

Based on new material from Germany and Spain, the echinoid “Lepidocentrus” ibericusfrom the Early Devonian (Emsian) of northern Spain is shown to be congeneric with Rhenechinusfrom the Hunsrück Slate of south−western Germany. New information on the lantern, pedicellariae and internal structure of the theca is provided, and confirms this genus as a member of the Echinocystitidae–Proterocidaridae clade and the most primitive of all Devonian echinoids. The two environmental settings in which Rhenechinus is found are very different: the Spanish specimens come from a relatively shallow−water bryozoan meadow setting while the German specimens are preserved in a deep−water setting. We deduce that the rare echinoid specimens from the Hunsrück Slate are all allochthonous, whereas the Spanish material is preserved in situ.