Uncovering the hidden diversity of Mississippian crinoids (Crinoidea, Echinodermata) from Poland.

Partial crinoid crowns and aboral cups are reported from the Mississippian of Poland for the first time. Most specimens are partially disarticulated or isolated plates, which prevent identification to genus and species, but regardless these remains indicate a rich diversity of Mississippian crinoids in Poland during the Mississippian, especially during the late Viséan. ? sp. is described from the late Tournaisian of the Dębnik Anticline region. A high crinoid biodiversity occurred during late Viséan of the Holy Cross Mountains, including the camerate crinoids ? sp., Platycrinitidae Indeterminate; one flexible crinoid; and numerous eucladid crinoids, including (Phillips), three taxa represented by partial cups left in open nomenclature, and numerous additional taxa known only from isolated radial plates, brachial plates, and columnals. To date, the youngest occurrence of was the early Viséan of the United States, thus the present finding in upper Viséan extends this genus range. Furthermore, the occurrence of ? sp. expands the Western European range of this genus into the Tournaisian. A single partially disarticulated crown, Crinoidea Indeterminate B, is described from the Serpukhovian of the Upper Silesian Coal Basin. In addition, several echinoid test plates and spines are also reported.