Feeding in situ: direct proof for Cambrian herbivory and carnivory in the Barrandian area (Czech Republic)  

Several examples of in situ ecological interactions are presented from the Middle Cambrian Jince lagerstätte (Barrandia, Czech Republic). Primary consumption is observed in microbial mats with carbonaceous filaments, retrieved from stratigraphically higher levels of the Jince Formation, which were supposedly deposited in shallow water.  Several of these surfaces contain articulated exoskeletons of the opportunistic polymerid trilobite Ellipsocephalus hoffi, and complete specimens of the tiny hyolithids Jincelites vogeli embedded inside organically preserved microbial mats.  Both the trilobites and hyoliths represent an in situ assemblage of benthic primary consumers.

Hiding or scavenging behaviour is evidenced by several examples of the agnostid Peronopsis integra inside other invertebrates.  Two articulated exoskeletons of P. integra are entombed between the hypostome and the dorsal exoskeleton of the cephalic shield of a complete specimen of Paradoxides (Hydrocephalus) minor; another intact exoskeleton of P. integra is preserved under thorax of a carcass of P. minor. A holaspid specimen of P. integra, with hypostome in situ, occurs inside of the hyolithid conch of J. vogeli. Peronopsis may have fed on deteriorating soft tissue of the containing organism, or dwelt within the host for protection from predation, bad weather or moulting.

Numerous articulated holaspids of P. integra associated with late meraspid to early holaspid specimens of Paradoxides paradoxissimus gracilis cover slabs with partially disarticulated large specimens of the edrioasteroid Stromatocystites pentangularis and/or the cystoids Akadocrinus in lower levels of the P. paradoxissimus gracilis Zone in the Jince Formation.  This may indicate scavenging.

The large flattened thecae of the edrioasteroid S. pentangularis sometimes contain a number of the bradoriid Konicekion; eight to over sixty individuals may be present in a single edrioasteroid, some of which are in the “butterfly position”. This mass occurrence of bradoriids represents the oldest known direct evidence of carnivorous behaviour for these arthropods, reflecting either hunting or opportunistic scavenging.