Trilobites offer the opportunity to explore postembryonic development within the fossil record of arthropod evolution. In contrast to most trilobites, the Silurian proetid Aulacopleura konincki from the Czech Republic exhibits marked variation in the mature number of thoracic segments, with five morphs with 18-22 thoracic segments. The combination of abundant articulated specimens available fro...

The Trilobita were characterized by a cephalic region in which the biomineralized exoskeleton showed relatively high morphological differentiation among a taxonomically stable set of well defined segments, and an ontogenetically and taxonomically dynamic trunk region in which both exoskeletal segments and ventral appendages were similar in overall form. Ventral appendages were homonomous biramo...

The Cambrian 'Orsten' fauna comprises exceptionally preserved and phosphatised microscopic arthropods. The external morphology of these fossils is well known, but their internal soft-tissue anatomy has remained virtually unknown. Here, we report the first non-biomineralised tissues from a juvenile polymerid trilobite, represented by digestive structures, glands, and connective strands harboured...

Abstract The cosmopolitan genus Gondwanaspis is one of two post-Taghanic (late Givetian to Frasnian) odontopleurid genera and the only Odontopleurida surviving Lower Kellwasser Event, finally disappearing at Upper Event. Although it known from Frasnian Australia, Germany, France, Morocco, Russia, findings are comparatively rare. Here we present eisbornensis n. sp. probable lower Beul section ne...