Pseudopolyconites slovenicus n . sp . resedimented to Paleocene flysch breccia of the So ~ a river valley ( Slovenia ) Pseudopolyconites slovenicus n . sp . presedimentiran v paleocensko fli

An entirely preserved large specimen of Upper Cretaceous rudist Psedopolyconites slovenicus n. sp. is described, characterized by the low and broad lower valve surrounded by a thick envelope of tiny straight tubules. The specimen was redeposited in Paleocene from the northern edge of Adriatic-Dinaric carbonate platform into a marginal part of the flysch basin.


Introduction
At the Bitež settlement 2 km north of Grgar and 6 km southeast of Anhovo ( Fig. 1) the owner of property Ivan Štrukelj found a large specimen of Upper Cretaceous rudist of the Polyconites genus in the excavation for a farm building in Paleocene breccia. The specimen is preserved in the Gorica Museum at Nova Gorica (Stanislav Ba~ar's museal exhibition of fossils at Ajdov{~ina,arch. no. 8142).
Finds of resedimented rudists in Paleocene flysch of the So~a river valley have been described already at the beginning of 20 th century. Numerous fossils were found, and registered in their writings already by KOSSMAT (1906KOSSMAT ( , 1908KOSSMAT ( , 1909KOSSMAT ( , 1913KOSSMAT ( , 1920 and WINKLER (1920WINKLER ( , 1923, but only WIONTZEK (1934) more precisely determined and described the collected fossil material, to which he added also his own rudist collection. BUSER (1986BUSER ( ,1987 who mapped in the frame of the Basic geologic map of SFR Yugoslavia the sheet Tolmin and Videm (Udine), found in flysch beds of the So~a valley numerous new localities of resedimented rudists (BUSER et al., 1988). D. PEJOVI} (1996) among collected rudists of Podbrdo flysch cyclotheme determined the species Vaccinites giordanii (Pirona), Hippuritella cornucopiae (Defrance) and the new species Pironaea buseri Pejovi}. doi:10.5474/geologija.2009.004 Collecting of rudists in Paleocene flysch beds in surroundings of Anhovo was carried out between 1999 and 2000 by Jurkov{ek who assembled a large collection of redeposited rudist fauna in which the following species have been determined (PLENI~AR, 2005;PLENI~AR et al., 2001) Parona and Offneria cf. italica Masse. All described fossils were redeposited in Paleocene to the flysch environment. For certain species on the basis of comparison with species found in primary Cretaceous platform carbonate rocks the exact location of their primary source and stratigraphic position could be established, while for some of them (e.g. the genus Pironaea) we presume that they lived at the edge of the carbonate platform which became later in totality eroded.

Geologic description
Upper Cretaceous and Paleocene beds with resedimented rudists are developed in Slovenia in the region of External Dinarides only. The flysch basin was shifted already end of Cretaceous from the area of Slovenian basin to the region of Adriatic-Dinaric carbonate platform. Flysch between Grgar and Anhovo belongs predominantly to the marginal respectively proximal part of the flysch basin, therefore it consists numerous intercalations of calcareous and conglomeratic breccia as a result of submarine slumps (SKABERNE, 2003;PO-GA~NIK et al., in press). They are up to several tens of meters thick, and they locally predominate over interbedding of marlstone, sandstone and calcarenite. KU{~ER with co-workers (1976) reported limestone blocks up to 100 m long and 30 m thick. To very large calcareous olistoliths belong probably also the Cretaceous limestone southeast of Anhovo that was marked as smaller tectonically delimited blocks within the Paleocene flysch on the Basic geologic map, sheet Tolmin and Videm by BUSER (1987).
The Paleocene flysch between Anhovo and Grgar contains next to well preserved rudists and fragments of rudist limestone also pieces of various Triassic and Jurassic limestones. Nummulites and alveolinas, otherwise frequent fossils in younger flysch levels of this area have not been recorded so far either in cement or among breccia fragments. The Lower to Upper Paleocene age of flysch was determined only locally by nannoplankton which, however, does not exclude the possibility of Eocene beds in the upper part of flysch sedimentation.
At Bitež lies the breccia with grey, grey green and brown violet marly cement just above the erosional boundary with the Upper Cretaceous limestone from which rudists of genera Durania, Gorjanovicia, Rajka, Sauvagesia and Lapeirouseia have been mentioned by BUSER (1986). In this area is characteristic for the Upper Cretaceous platform development also the horizon with rounded rudist valves that belong mostly to genus Sabinia.
In addition to the new species P. slovenicus in the Paleocene breccia above the earlier described Santonian-Campanian limestone also several other resedimented rudists were collected. They will be the object of future research together with regional geologic investigations and examination of nannoplankton in marly cement.

Description
The entire specimen of rudist (the lower and upper valves) is slightly eroded on surface. The relatively low and broad lower valve together with the convex upper valve measures in height 14 cm and in diameter 21 cm at the commissular part at contact of the two valves. The lower valve is of shallow conical (dishlike) shape, and the upper valve represents its convex cover. The lower valve is covered with an envelope of »growth tubules«. Tubules are straight, and appear on the external side of valve as fine parallel furrows. The »growth tubules« are not observed on upper valve.
A horizontal section across the upper valve has been made at a distance of 4 cm below the commissure. In the section, internal structure of lower valve consisting of several layers is visible. On its external side it is surrounded by the envelope of straight »growth tubules« of about 1 mm diameter. The tubular envelope is 10 to 20 mm wide. The envelope of »growth tubules« is followed by a cortical layer whose structure is not clear (it is probably a lamellar layer). Thickness of this layer varies largely, from 3 mm on the side of ligamen- tal column to around 10 mm in the siphonal zone. This layer is separated from the internal part of valve by a rather uniformly thick intermediate layer that is recrystallized, and from it protrudes the ligamental column L. On the internal side of the lower valve follows an irregularly thick darker laminar layer that laterally passes into variously thick, irregularly shaped prisms of the prismatic layer.
The lower valve has a flat to slightly concave anterior side and a convex posterior, or cardinal side. The siphonal pseudocolumns E and S are poorly expressed.
Very important in genus Pseudopolyconites is the shape of the ligamental column in various horizontal sections of the lower valve that display various stages of ontogenetic evolution of the same individual. In the described specimen of P. slovenicus, in the section of lower valve that corresponds to later ontogenetic stages, is the head of ligamental column large and of pentagonal outline with a diameter of up to 13 mm. The stem at ligamental column is relatively thin, and measures in the horizontal section of valve (4 cm below the commissure) 8 mm in length.
Position of both teeth is not clear. Probably the teeth are oriented at a small angle to axis of the ligamental column.

Remarks
Species P. slovenicus is to the most similar to species P. serbicus Milovanovi} (MILOVANOVI}, 1939;PEJOVI} & SLADI}-TRIFUNOVI}, 1977) and P. dechaseauxae Milovanovi} & Sladi} (MILOVA-NOVI} & SLADI}, 1957). The first one has a large, oblong head of ligamental column in the late ontogenetic stage, and the shape of a thin hook in the early ontogenetic stage. The stem of ligamental column in species P. serbicus is thicker as in species P. slovenicus. The section of lower valve is in P. serbicus of a more triangular shape, and round in P. slovenicus. P. dechaseauxae has a very thick stem, a thicker and broader posterior side of distal part of the head at ligamental column in the late ontogenetic stage, a concave upper valve and a more triangular outline of the cross-section of its highest part, in comparison to species P. slovenicus.