A unique occurrence of stalked crinoids in the Eocene Popiele Beds (Outer Carpathians, Poland)

The Eocene Popiele Beds of the Skole Nappe (Outer Carpathians, Poland) are exceptional among the predominantly deep-water lithofacies of Outer Carpathians because of their proximal origin and subsequent mass resedimentation into deeper parts of the flysch basin. Consequently, this lithostratigraphic unit contains unusually rich macrofossil assemblages within otherwise generally fossil-poor flysch successions. During a multidisciplinary study of the fossiliferous mudstone matrix from the Koniusza locality, we identified, in addition to abundant foraminifera, molluscs, bryozoans, other marine organisms, and abundant palynological organic matter, rare remains of stalked crinoids, including isocrinids, and bourgueticrinids. These echinoderms are represented by small columnals that show minimal abrasion, and in some cases little disarticulation indicating rapid burial and limited transport. Their rarity and small size may suggest the presence of a relict population inhabiting environments already strongly affected by post-Mesozoic ecological restructuring. At Koniusza, this setting was most likely a nearshore, nutrient-rich marine environment influenced by strong terrestrial input. Sedimentological and palynological evidence indicates a shallow-neritic setting with normal salinity and elevated productivity. The occurrence of stalked crinoids in such a proximal, probably shallow-marine environment provides new insight into the palaeoenvironmental preferences of these echinoderms and their ecological persistence during the Palaeogene.