FIRST DETERMINATION OF RUDISTS (BIVALVIA) FROM NE IRAQ: SYSTEMATIC PALAEONTOLOGY AND PALAEOBIOGEOGRAPHY

The Maastrichtian Aqra Formation around Mawat-Chwarta (Sulaimaniya city) in NE Iraq consists mainly of coarse grained detrital limestone, locally containing terrigenous clastics, and is characterized by abundant rudists in life position. The rudist biostromes are very common in the formation and benthic foraminifers, gastropods and non-rudist bivalves with scarcer echinoderms and solitary corals are associated with the rudists. This first determination of rudists from NE Iraq recognizes the following species, Dictyoptychus aff. morgani, Sauvagesia somalica, Hippurites cornucopiae, Praeradiolites subtoucasi and Lapeirousia jouanneti, as well as some indeterminable radiolitid sections. This rudist fauna is assigned to the Hippurites cornucopiae interval zone indicating a mid to Late Maastrichtian age. Dictyoptychus is an endemic rudist genus for the Arabian Plate, to which Sauvagesia somalica also seems to be limited. Other determined species are recorded mostly from the central-eastern Mediterranean Tethys, and to a lesser extend from the Arabian Plate. The determination of rudists from NE Iraq fills an important gap in terms of the taxonomic database and palaeobiogeography. The data on the rudist fauna reveals the existence of a shallow marine dispersal route for rudist larvae during the Maastrichtian along the area of the present Zagros fold-thrust belt from SE Turkey across NE Iraq towards SW Iran.