Glabrobournonia Morris and Skelton (Rudist, Bivalvia) from the Campanian–Maastrichtian of Türkiye: Taxonomy, palaeoecology and palaeobiogeography

Abstract

A re-examination of the specimens described as Bournonia anatolica Özer and Bournonia sp. from central and southeastern Anatolia, Türkiye reveals that they have diagnostic characteristics of the genus Glabrobournonia Morris and Skelton. New rudist material from the middle Campanian to late Maastrichtian mixed siliciclastic-carbonate sequences in the Sakarya Zone (Eastern and Central Pontides), in the east of the Anatolid–Tauride Block and in southeastern Anatolia (north of the Arabian Platform) in Türkiye also showed the occurrence of Glabrobournonia anatolica (Özer) and Glabrobournonia arabica Morris and Skelton. Glabrobournonia anatolica is characterised by a large, rectangular right valve with pronounced growth lamellae, a salient ventral carina and interband, a less salient dorsal carina, a concave indentation anterior band, a slightly concave posterior band and broad and smooth anterior surface as well as the absence of radial ribbing and ligamentary infolding. Glabrobournonia arabica has the diagnostic features of the species, such as small valves, conical right valves with a smooth surface, ventral and dorsal carinae and two concave indentations of anterior and posterior bands separated by an interband. The palaeoecological characteristics of these lateral clinger morphotypes are presented according to growth geometries. For the cosmopolitan genus Glabrobournonia, two main migration routes have been proposed for the Campanian–Maastrichtian time: one along the southern margin of the Tethys from the United Arab Emirates–Oman border region to the Zagros (Iran) and southeastern Anatolia, connecting to the northern margin of the Tethys to the Anatolid–Tauride Block and the Sakarya Zone in Türkiye, and another from the United Arab Emirates–Oman border region to the Zagros Zone (Iran) and the Tarim Basin, connecting the northern and southern margins of the eastern Tethys.