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Ventral valve
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Schizophoria provulvaria
Phylum: Brachiopoda
Genus: Schizophoria Species: Schizophoria provulvaria Location found: Baton River |
Schizophoria provulvaria and Schizophoria vulvaria are closely related species, distinguished in this area mainly by where they occur. S. provulvaria is limited to the Baton Formation, while S. vulvaria occurs in the Reefton deposits. Strusz (1972), however, argues that they are also chronologically distinct with P. provulvaria being replaced in the late Emsian stage by P. vulvaria. If this is the case, they give evidence to regard the Baton River deposits as slightly older than the Reefton sequence.
Morphologically, the two species are very similar and difficult to distinguish apart. They are also apparently cosmopolitan, with a wide global spread. A detailed description and photographs of P. vulvaria from Europe is given by Binnekamp (1965). |
Description, based on Binnekamp (1965): Rounded subcircular outline,slightly transverse. Greatest width at mid-length, maximum thickness near the umbo. Pedicle (i.e. ventral) valve moderately convex near the umbo, concave near the front. Brachial (dorsal) valve strongly convex with a flattened top. Very weak sulcus [in young specimens] which becomes accentuated in older specimens and inflates the forward part of the valve. Frontal part of the commissure sulcate. Hinge line straight, about half as wide as the width of the valve. Cardinal area oriented almost perpendicular to the plane of the valves. Open delthyrium. Area of the brachial valve in a direct line with the plane of the valves. In the notothyrium the top of the central part of the cardinal process is visible.Whole surface finely stellate. Costellae bifurcating. Growth-lines rather strong. Further Reading: Binnekamp, J.G. 1965 Lower Devonian brachiopods and stratigraphy of North Valencia (Cantabrian Mountains, Spain). Leidse Geologische Mededelingen, 33, 1-62. Strusz, D.L. et al. 1972 Correlation of the Lower Devonian rocks of Australasia. Journal of the Geological Society of Australia 18(4), 427-455. |