Callovian (Middle Jurassic) Sphriganaria (Brachiopoda) from the Jordan Valley (Middle East)

ABSTRACT

Middle Jurassic terebratulide brachiopods from the Jordan Valley are herein described and a new taxon is added to the previous faunal list. The Callovian rocks (Mughanniyya Formation) of the Tel el Dhahab section have yielded the following terebratulide taxa: Sphriganaria capax, S. costata, S. costellata, S. curtirostra, S. expansa, S. irregularis, S. subcircularis, S. nasuta, S. sp. 1, and S.? sp. 2. A new species Sphriganaria anyamiae sp. nov. is formally described herein. Internal characters of Sphriganaria costata, S. expansa, and S. nosuta have been studied. On the basis of shell microstructure, crural bases, outer and inner hinge plates were differentiated and defined for the first time in the genus Sphriganaria. The secondary layer is homogeneous built of very fine fibres, predominantly anisometric-like in cross-section, 25‒40 μm wide and 8‒15 μm thick. The Callovian Mughanniyya Formation of northwest Jordan is dominated by highly fossiliferous limestones intercalated with marlstone beds with very diverse brachiopod fauna, deposited in shallow, low-energy waters very near the equator. A paleobiogeographic interpretation of the brachiopod faunas in the Ethiopian Province suggests that brachiopods migrated from the north in the Early Jurassic and later became isolated for the remainder of the period.