First report of myalinid bivalves in the Lower Carboniferous of the Hakkari Basin, SE Turkey: paleoecologic and paleogeographic implications

Authors: İZZET HOŞGÖR

Abstract: Knowledge of the Late Paleozoic sedimentary history of the northern Gondwana shelf is advanced by new data from the Şort Dere section (Hakkari Basin). Early Carboniferous myalinid bivalves from the Middle East are reported here for the first time. The pre-Permian basement of the Hakkari Basin consists of a Lower Carboniferous sedimentary sequence including the Köprülü and Belek formations. The Köprülü Formation has yielded rich assemblages of vertebrates and invertebrates. Hitherto myalinid bivalves were unknown from this formation; this paper reports the discovery of small and poorly calcified myaliniform shells from two thin beds in the middle part of the Köprülü Formation of the Şort Dere section in the Zap Valley. The morphological characteristics of the specimens, especially the umbonal region with the numerous rounded wrinkles, suggest that it probably belongs to an undescribed species of Selenimyalina Newell, 1942. Based on this record, the state of the art of warm-water myalinid taxa in the Paleotethyan Realm is shortly discussed with a focus on the pteriomorph bivalve faunas within a global scenario for both paleobiogeography and patterns of Gondwana-Laurussia faunal exchange. The new occurrence is one of the most important pteriomorph bivalve records ever made in Southeast Turkey, helping to assist paleogeographic reconstructions of the Paleotethyan paleocontinents.

Keywords: Lower Mississippian, Köprülü Formation, Kulm Facies, Gondwana shelf, Paleotethys, Selenimyalina

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