Trace fossil nomenclature and the Planolites-Palaeophycus dilemma

A thorough reevaluation of the ichnogenera Planolites Nicholson and Palaeophycus Hall shows that Planolite represents active backfilling of sediment in an ephemeral burrow constructed by a mobile deposit feeder and Palaiophycus represents passive sedimentation within an open dwelling burrow constructing by a predaceous or suspension-feeding animal.