Palaeoecological aspects of an Ordovician Tretaspis fauna

Different isocommunity lineages with successive metaoommunities constitute the Tretaspis fauna of central, north, and west Europe. The fauna is strongly dominated by trilobites. Based on collections from one fossiliferous level in one locality a trial is made to grasp the autecology of some trilobite constituents. Most trilobites in the fauna were obviously benthic. Odontopleurids and Tretaspis show adaptations for a life on a flat surface and the latter probably burrowed shallowly. The food may have consisted of soft-skinned animals. Panderia may have burrowed backwards to form a dwelling burrow. Remopleurides and Cyclopyge have large eyes and large space for appendage muscles and were probably agile hunters, nektobenthic or possifbly pelagic. The excessive development of alimentary caeca in agnostids is a character shared with extant arthropods feeding on fluids, and in combination with the flattened shape this indicates that agnostids, including Trinodus, were ectoparasitic. The sea is judged to have been about 100m deep.