Schizoria elongata 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 : 201-202

Schizoria elongata Cooper, 1989

Fig. 3H.

1989 Schizoria elongata sp. nov.; Cooper 1989: 55–56, fig. 31: 14, figs. 17–27.

Material.—Three articulated specimens: AMNH FI− 72407, AMNH FI− 72408, AMNH FI− 72411, bed S−7, Mughanniyya Formation (Callovian, upper Middle Jurassic); Tel el Dhahab section, Jordan.

Description.—Shells small ( Table 8), elongate but slightly oval, maximum width just anterior to midvalve. Dorsal valve deeper and asymmetrically more convex than ventral valve with the convexity more pronounced posteriorly; apical angle acute; anterior commissure on larger shell barely uniplicate

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

but on smaller shell not preserved well enough to determine morphology; lateral commissure straight. Beak narrow, long; foramen medium, mesothyrid, tubular; deltidial plates disjunct, ventral interarea low. Costae moderate and angular in cross section but subangular and rounded on smaller shell due to weathering and exfoliation; bifurcated and intercalated mostly on umbos ranging from 24–25 in number.

Ventral valve moderately convex in lateral profile and highly domed in anterior view. Umbonal region swollen, more so in large shell. Fold with 5 costae; 6 to 7 costae on flank of ventral valve.

Dorsal valve swollen posteriorly but less so in smaller specimen; highly domed in anterior view on the larger shell. Sulcus with 4 costae; 5 to 7 costae on flank.

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

Discussion.—The shells closely resemble Cooper’s (1989) Schizoria elongata in many respects but differ in that the pedicle foramen here is mesothyrid and is slightly larger than in his specimens. Schizoria intermedia Cooper, 1989 has more widely spaced costae on the flanks, fold, and sulcus with no bifurcations and rare intercalations; it also has a strongly uniplicate anterior commissure. Sphenorhynchia plicatella differs from Schizoria elongata in its less elongate−oval general outline, more evenly biconvex valves, shorter and more massive umbo, and less numerous costellae.

Stratigraphic and geographic range.—Bajocian to Callovian; Saudi Arabia, Jordan.