Upper Callovian and Oxfordian molluscs and brachiopods from selected localities of the Kraków-Częstochowa Upland and the Świętokrzyskie Mountains, Poland

Abstract

The aim of the study was the taxonomic, morphological, ecological and stratigraphic characterization of marine invertebrate groups from the localities of Wiek and Wysoka (Krakow-Częstochowa Upland) and Gnieździska (Świętokrzyskie Mountains). All of these three localities were unused quarries where limestone was once mined. The material consisted of a total of 756 fossils collected by the author from the studied sites or constituting part of the collections of the Department of Vertebrate Ecology and Palaeontology at the University of Environmental and Life Sciences in Wrocław. When describing and marking the fossils, attention was paid to the state of preservation, morphology, size, shape and the presence of structures characteristic of a given taxon. Among the studied material were fossils of gastropods, bivalves, ammonites, belemnites, and brachiopods. These organisms were found in upper Callovian (Middle Jurassic) and Oxfordian (Upper Jurassic) sediments and are approximately 157.3–166.1 million years old. Different groups of invertebrates dominated in the material collections from individual sites. Among the fossils from the Wiek quarry, the most numerous were brachiopods, the material from the Wysoka locality was dominated by ammonites, and the most numerous group in the collection from the Gnieździska quarry were belemnites. In total, 18 genera belonging to 13 families were recorded. The most numerous group among the studied fossils were Ammonitida, mostly represented by the genus Perisphinctes. In the collection from the Wysoka quarry, a single ammonite shell belonging to the genus Horioceras was recorded, which has not been recorded at this site so far. Among the collected ammonites, the genera Cardioceras, Lissoceratoides, and Trimarginites were also distinguished. The most diverse group among the collected fossils were brachiopods, of which eight genera were recorded: Lacunosella, Septaliphoria, Epithyris, Juralina, Loboidothyris, Sellithyris, Zeillerina, and Terebratulina. The studied material also revealed the presence of one genus of gastropods—Nerinea, two genera of bivalves—Lima and Posidonia, and two general of belemnites—Belemnopsis and Hibolites. These organisms inhabited the shallow and warm shelf sea that covered a large area of present territory of Poland during the Jurassic period.