Daghanirhynchia? triangulata Cooper, 1989

Feldman, Howard R., Schemm-Gregory, Mena, Ahmad, Fayez & Wilson, Mark A., 2012, Jurassic rhynchonellide brachiopods from the Jordan Valley, Acta Palaeontologica Polonica 57 (1), pp. 191-204 : 199-200

Daghanirhynchia? triangulata Cooper, 1989

Fig. 3E.

1989 Daghanirhynchia? triangulata sp. nov.; Cooper 1989: 28–29, pl. 7: 6–21, pl. 11: 11–15.

Material.—Two articulated specimens: AMNH FI− 72397, bed S−7, Mughanniyya Formation (Callovian, upper Middle Jurassic), Tel el Dhahab section; AMNH 72398, bed 21a, Hamam Formation, Arda section, Jordan.

Description.—There are two shells in the collection ( Table 5) tentatively assigned to Daghanirhynchia? triangulata Cooper, 1989 . The specimens are triangular with maximum width considerably past midlength; slightly dorsibiconvex, strongly uniplicate anterior commissure, lateral commissure straight, beak suberect, costae strong, coarse and narrow, numbering 16–17.

Ventral valve barely convex in lateral view, almost flat, concave in anterior profile. Sulcus originates just past umbonal region, occupied by three costae. Linguiform extension long and fairly narrow; ventral interarea low; 6–7 costae on flanks.

Dorsal valve slightly convex in lateral view, strongly domed in anterior view, sides becoming steeper as lateral margins approached. Fold begins at about midlength, occupied by 4 costae, slightly less than half the valve width; 6 costae on flanks.

The internal structures of the shells are unknown due to a lack of sufficient material for serial sectioning.

Discussion.—The shell closely resembles Cooper’s (1989)

http://dx.doi.org/10.4202/app.2010.0092

Daghanirhynchia? triangulata in its triangular outline and costation and is tentatively placed in that taxon until additional material can be studied.

Stratigraphic and geographic range.—Callovian, Jordan.