Hyžný M., Hudáčková N. & Szalma Š., 2015: Taphonomy and differential diversity of the Middle Miocene decapod crustaceans from the Plášťovce Member of the Sebechleby Formation (Novohrad-Nógrad Basin, Slovakia), with remarks on palaeobiogeography. Acta Geologica Slovaca, 7, 2, 139–154.

Taphonomy and differential diversity of the Middle Miocene decapod crustaceans from the Plášťovce Member of the Sebechleby Formation (Novohrad-Nógrad Basin, Slovakia), with remarks on palaeobiogeography

Tafonómia a diverzita desaťnožcov stredného miocénu plášťovských vrstiev sebechlebskej formácie (Novohradská panva, Slovenská Republika) a ich paleobiogeografický význam

Matúš Hyžný^1,2, Natália Hudáčková² & Štefan Szalma³

¹Naturhistorisches Museum Wien, Geologisch-Paläontologische Abteilung, Burgring 7, 1010 Vienna, Austria; hyzny.matus@gmail.com
²Department of Geology and Palaeontology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia; hudackova@fns.uniba.sk
³935 82 Plášťovce 87, Slovakia; szalma.istvan7@gmail.com

Abstract

Decapod crustacean assemblages from the Middle Miocene (lower ‘Badenian’=Langhian) volcanoclastic Plášťovce Beds (Sebechleby Formation) in the Slovakian part of the Novohrad-Nógrad Basin comprise five species in five families (Callianassidae, Laomediidae, Munididae, Cancridae and Retroplumidae) and are dominated by the cancrid crab Tasadia carniolica (Bittner, 1884). Munida sp. constitutes the first record of this genus from Slovakia and the second from the European Neogene. Burrowing shrimp (Jaxea kuemeli Bachmayer, 1954) are associated with burrows tentatively attributed to this species. The occurrence of Retropluma slovenica Gašparič & Hyžný, 2014, previously recorded from the Lower Miocene of Slovenia, extends both the geographical distribution and stratigraphical range of the species. Differential decapod diversity at four localities in the Plášťovce area can be explained by collecting bias and palaeoenvironmental factors. The palaeosetting is interpreted as a muddy-bottom, nearshore zone with a water depth of approximately 100 m. Abundant articulated crabs suggest rapid burial. Third maxillipeds in open posture in some specimens may indicate respiratory stress of the animals, suggesting episodic events of rapid volcanoclastic flows responsible for killing crabs and promoting their preservation. Species composition of the decapod fauna of the Plášťovce Beds further strengthens similarities with Miocene faunas from the North Sea Basin.

Key words: Decapoda, Middle Miocene, Novohrad-Nógrad Basin, Sebechleby Formation, Plášťovce Member, volcanoclastics, taphonomy, diversity, palaeobiogeography

Manuscript received: 2015-03-13

Revised version accepted: 2015-09-14