Revision of the rudist genus Orestella Lupu, 1982 (Bivalvia, Order Hippuritida) from the Upper Cretaceous of Romania Sacit € Ozer a, * , Liana S  as  aran b a Dokuz Eylül University, Engineering Faculty, Department of Geological Engineering, Tınaztepe Campus, Buca, TR-35160 _ Izmir, Turkey b Babes ¸-Bolyai University, Department of Geology, 1 Mihail Kog alniceanu Street, 400084 Cluj-Napoca, Romania article info Article history: Received 22 June 2013 Accepted in revised form 3 September 2014 Available online Keywords: Rudist Bivalvia Orestella Revision Upper Cretaceous Romania abstract Re-examination of the Orestella Lupu, 1982 (formerly Orestia Lupu, 1972) type material in the Geological Institute, Bucharest, Romania, revealed the need for revision of its taxonomic status. The holotype and paratypes of this taxon show the diagnostic characteristics of the Family Hippuritidae, not the Radio- litidae as previously indicated. This genus should therefore be transferred to the Hippuritidae. The structure of the pillars, the ligamental ridge and the outer shell layer of the right valve as illustrated by the type material point to an affiliation either with Hippurites or with Hippuritella. We discuss this assignment by taking into account the similarities with Hippurites organisans (de Montfort), Hippuritella lapeirousei Goldfuss and Hippuritella variabilis (Munier-Chalmas). The stratigraphic framework of the study material is also discussed with respect to the Upper Cretaceous successions in the Central-Eastern Carpathians of Romania. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction The new rudist genus Orestia was described and assigned to the Radiolitidae by Lupu (1972) based on her interpretation of the outer shell layer of the right valve in five specimens recorded by Mir aut ¸  a and Mir aut ¸  a (1964) from the bioclastic breccia of Campa- nianeMaastrichtian age (Lower Hangu Beds) from the Cuejdiu Valley, north of the town of Piatra Neamt in the central area of the East Carpathians (Fig. 1). Later, Lupu (1982) replaced the genus name by Orestella due to preoccupation of the former name by Orestia Chevrolat in Dejean, 1836, p. 440 (Insecta, Order Coleop- tera). Subsequently, no additional specimens of this taxon were recorded either in the Romanian Upper Cretaceous rudist-bearing formations or in the Mediterranean Tethys area in general (cf. Steuber, 2002). Nevertheless, the assignment of Orestella to the Family Radiolitidae was carried over in the classification of rudists proposed for the revised Bivalvia volumes of the ‘Treatise on Invertebrate Paleontology’ (Carter et al., 2011), and also more recently by Skelton (2013). The main aim of our study is the taxonomic revision of Orestella Lupu, 1982 based on re-investigation of the holotype and paratypes housed in the Geological Institute of Romania collection in Bucharest. The age and stratigraphic assignment of the study ma- terial are also discussed. A new taxonomic status of Orestella is proposed for inclusion in the revision of the Bivalvia volumes of the ‘Treatise on Invertebrate Paleontology’. 2. Geological setting The specimens were collected by Mir aut ¸  a and Mir aut ¸  a (1964) from the Cuejdiu Valley, north of Piatra-Neamt ¸ . Stratigraphically, the deposits belong to the Leps ¸ a Formation from the Vrancea Nappe (Marginal Folds Nappe, sensu S andulescu, 1984) represent- ing the external tectonic units of the Outer Moldavidian domain of the Romanian Carpathians (Fig. 1). The sedimentary succession of the Vrancea Nappe (Marginal Folds) range in age from the Early Cretaceous to the Early Miocene (Dumitrescu, 1952; B ancil a, 1958; Grasu et al., 1988; Guerrera et al., 2012) and the following units crop out in ascending stratigraphic order: the S arata, Leps ¸ a, Piatra Uscat a, Jgheabu Mare, Doamna Limestone, Bisericani, Globigerina Marls and Luc aces ¸ ti Sandstone, Lower Menilite, Bituminous Marl, Lower Dysodilic Shale with Kliwa Sandstones, Upper Dysodilic Shale and Menilite and, finally, Gura S ¸ oimului formations (Micl aus ¸ et al., 2010). In our study area from the Cuejdiu basin, the Vrancea Nappe crops out in the Bistrit ¸ a tectonic half-window (B ancil a, 1958; Grasu et al., 1988) and the EarlyeLate Cretaceous deposits belong to the S arata and Leps ¸a Formations (Guerrera et al., 2012). The specimens of Orestella under review originate from the * Corresponding author. E-mail address: sacit.ozer@deu.edu.tr (S. € Ozer). Contents lists available at ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes http://dx.doi.org/10.1016/j.cretres.2014.09.003 0195-6671/© 2014 Elsevier Ltd. All rights reserved. Cretaceous Research 52 (2015) 73e82