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Fascicostella batonensis (LPB4_40) from Baton River
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Fascicostella batonensis
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Like many fossils from the Baton River, it is difficult to obtain good specimens of this species due to the deformation that the deposits have experienced during burial, compaction and subsequent tectonic activity. There is also little information on this species in the palantaeological literature to guide identification. Identification here is therefore uncertain. In addition, the species has undergone several name changes in its history. Originally identified as Orthis gervillei, it was renamed Fascicostello gervillei by Defrance, and under that name was described by Shirley (1938) - see panel to right. The name F. batonensis was assigned by Walmsley & Boucot (1974).
It has been regarded as a characteristic Devonian species, and thus was used to help distinguish the Silurian-Devonian boundary in Europe. |
Description (Shirley 1938): Shell substance punctate. Outline subcircular, general contour dalmanelloid. Dorsal valve flat except for a faint sinus; ornamented with angular ribs arranged in bundles in each of which one is more elevated; the sinus is occupied by a bundle of finer ribs. Ventral valve convex with similar ornament ; the fold only indicated by somewhat enlarged ribs. One specimen . . . shows the dorsal interior. Cardinal process bifid, elongated forward into a septum extending two-thirds of the length of the valve ; crura strong and thick with bases diverging at about a right angle, their exterior surfaces furrowed to receive the crenulations of the teeth. Ventral interior: teeth prominent with erenulate interior and exterior surfaces; rise from swellings on the side of the valve without supporting plates. A faint line marks off the shield-shaped undivided muscle impression. Two pallial trunks run parallel medially in the impression and for some distance forward. |
Further Reading:
Shirley, J. 1938 The fauna of the Baton River beds (Devonian), New Zealand. Quarterly Journal of the Geological Society 94, 459-506.
Williams, A. & Wright, A.D. 1963 The Classification of the "Orthis testudinaria Dalman" group of brachiopods. Journal of Palaeontology 37 (1), 1-32.
Shirley, J. 1938 The fauna of the Baton River beds (Devonian), New Zealand. Quarterly Journal of the Geological Society 94, 459-506.
Williams, A. & Wright, A.D. 1963 The Classification of the "Orthis testudinaria Dalman" group of brachiopods. Journal of Palaeontology 37 (1), 1-32.