Acta Geologica Polonica, Vol. 68 (2018), No. 4, pp. 571–596 DOI: 10.1515/agp-2018-0032 A new Danian echinoid assemblage from the Greensand in the Kazimierz Dolny area, central Poland: taxonomy, taphonomy and sedimentological implications MARCIN MACHALSKI1 and JOHN W.M. JAGT2 1 Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warszawa, Poland. E-mail:
[email protected] 2 Natuurhistorisch Museum Maastricht, De Bosquetplein 6-7, 6211 KJ Maastricht, The Netherlands. E-mail:
[email protected] ABSTRACT: Machalski, M. and Jagt, J.W.M. 2018. A new Danian echinoid assemblage from the Greensand in the Kazimierz Dolny area, central Poland: taxonomy, taphonomy and sedimentological implications. Acta Geologica Polonica, 68 (4), 571–596. Warszawa. We describe a new echinoid assemblage, composed of specimens of Bolbaster sp., Cyclaster danicus (Schlüter, 1897), Diplodetus vistulensis (Kongiel, 1950) and Linthia? sp. in a distinctive phosphatic preservation, from the so-called Greensand, a marly glauconitic sandstone horizon at the base of the Danian succession in the Kazimierz Dolny area (central Poland). This assemblage presumably is of early Danian age, with Cyclaster dan- icus occurring in the lower Danian of Denmark and southern Sweden. The specimens are preserved as internal moulds, composed of phosphatised glauconitic sandstone, occasionally with some test material adhering. The genesis of these moulds involved the following steps: (1) infilling of tests of dead echinoids with glauconitic sand; (2) penetration of the infills by coelobiotic deposit-feeding organisms that produced burrows along the inner test surface; (3) early-diagenetic cementation of infills by calcium phosphate; and (4) exhumation and intraformational reworking of specimens, leading to abrasion, fragmentation and loss of test material in some individuals.