A lower Maastrichtian (Upper Cretaceous) concentration Lagerstatte of bourgueticrinid crinoids from the Miechow Trough (southern Poland)

Literature data have been reporting the exposures of Campanian-Maastrichtian sediments in the area between Ksiaz Wielki and Jedrzejow, southern Poland. Current studies showed that the upper Santonian sediments, at least locally, are also outcropping there, as evidenced by the occurrence of the stalkless crinoid Marsupites testudinarius. 88 bourgueticrinid cups and over 115 columnals of Bourgueticrinus sp. cf. ellipticus and Bourgueticrinus sp. were also found in the lower Maastrichtian deposits. In the newly exposed outcrop, many specimens of these taxa are occurring in a single layer forming a bourgueticrinid Konzentrat-Lagerstatte. The under-and overlying sediments only delivered disarticulated and relatively small ossicles (cups, columnals, radicular cirri). The state of preservation of crinoidal elements indicates that the material had been undergone a long post-mortem transportation, or is a result of repeated episodes of transportation for short distances. Other crinoids (e.g., isocrinids or roveacrinids) were not found associated with the bourgueticrinids, most likely because of taphonomic sorting or due to their small sizes enabled their washing out. Some of the recorded cups display bite marks, suggesting they had been victims of predators, probably teleost fishes or sea urchins. In contrast to other Mesozoic crinoids, the overall frequency of predation traces in this Lagerstatte level is relatively low.