New data on the trace fossil, Cruziana semiplicata (Furongian, Wiśniówka Sandstone Formation, Poland) : origin, ethology and producer

Cruziana semiplicata Salter is a well known ichnospecies, ascribed to trilobites. Despite that, there are still contradicting views on its origin (infaunal vs. epifaunal), the ethology represented (crawling vs. feeding) and the identity of its producer (a few trilobite genera were proposed). In this paper, new data are presented and com- bined to create a coherent interpretative model for Cruziana semiplicata. According to this new model, Cruziana semiplicata is a fossilized version of an epifaunal, pascichnial (feeding) trace produced by an organism, positioned above the seabed with only a few frontal appendages touching the depositional surface and processing the sedi- ment below. This model is based on observations of trace fossil morphology and neoichnological observations of the feeding behaviour of Triops australiensis. Also, a short geometrical comparison with the co-occurring Rusophycus polonicus is made to show that these trace fossils most likely had different trace makers.