Aszulcicrinus, a new genus of the Triassic crinoid family Dadocrinidae (Articulata; Encrinida) from Poland

Abstract

The new genus and species Aszulcicrinus pentebrachiatus of the family Dadocrinidae from the early Middle Triassic Lower Gogolin Formation of Upper Silesia Upland is described. In contrast to Dadocrinus, the second primibrachial of Aszulcicrinus is not axillary for articulation with two arms but articulates with a third primibrachial and the first pinnule. This character results in five unbranched arms, which is unique in the order Encrinida. The significance of this character is discussed and paedomorphic or ecophe otypic explanations are excluded. The presence of only five unbranched arms predominates through the ontogeneny of Aszulcicrinus from early postlarval to adult stage. Within the family Dadocrinidae (Aszulcicrinus - Dadocrinus - Carnallicrinus), a phylogenetic trend towards size increase coincident with increasing arm number and denser pinnulation is interpreted as an improvement in filter-feeding efficiency. The sedimentological and taphonomic setting of the obrutional conservation lagerstätte of the type locality is described.