Life habit and enrolment in Calymenacea (Trilobita) and their significance for classification

Abstract

The life habit of Neseuretus is reconstructed on the basis of functional analysis and compared with that of other Calymenacea. Neseuretus, like all Calymenidae, was probably a filter feeder, burrowing downward into the sediment, where it rested hidden in a U-shaped attitude. Homalonotidae developed frontal burrowing and Bathycheilidae probably lived on the sediment. These calymenid families have different enrolment and behavioural patterns. Enrolment structures are developed, analysis of which leads to an understanding of phylogeny. Bathycheilidae maintained an unspecialised spiral enrolment. Flexicalymeninae and Calymeninae developed an advanced spiral enrolment, while a pseudosphaeroidal enrolment was achieved along independent lines in Kerfornellinae and Homalonotidae.