Ripidiorhynchus, Sartenaer, 1966

Day, Jed & Over, D. Jeffrey, 2002, Post-extinction survivor fauna from the lowermost Famennian of eastern North America, Acta Palaeontologica Polonica 47 (2), pp. 189-202 : 196

Ripidiorhynchus ? sp.

Fig. 3E, F .

Material.—Two mature shells NYSM 15699, NYSM 15722, and a juvenile ventral valve NYSM 15694, 15 unnumbered partial compacted ventral and dorsal valves on parts and counterparts of split slabs.

Remarks.—The limited material (three partial ventral valves and numerous fragments) do not permit a definitive generic assignment. The angular plications originating near the beak of the ventral valve are a common feature seen in a number of genera known from upper Frasnian–lower Famennian deposits. It is likely that this form represents a species of Ripidiorhynchus Sartenaer (1966) . The best−preserved ventral valves are close to the Frasnian form R. kermanensis Brice (1999) illustrated by her from the Frasnian of Kerman Province of eastern Iran. The Hanover material is provisionally placed in that genus pending discovery of additional well−preserved shells in the Upper Devonian of New York.

The specimens ( Fig. 3E, F ) also bear an external resemblance to shells of Sinotectirostrum Sartenaer (1961a) . Of the species described from North America, the limited material (NYSM 15723 with shoulder angle of 115°) from the Hanover Shale is most similar to S. medicinale deceptum Sartenaer (1969 : his paratype GSC 15900) described from very low in the Sassenach Formation of western Alberta. Raasch (1989) lists species of Sinotectirostrum from six of his seven Famennian brachiopod zones (zones DFM1 to DFM6) that span the interval from the Lower Pa. triangularis through the Pa. trachytera zones of the Upper Devonian Famennian conodont zonation. Sartenaer (1969: fig. 2) portrays the range inception of S. medicinale deceptum very low in the Lower Pa. triangularis Zone , below species typical of his Eoparaphorynchus ZoneinwesternCanada.IftheHanoverspecimensprovetobe Sinotectirostrum , then the occurrence of this genus in New York (very low in the Lower Pa. triangularis Zone ) would be similar to its lowest occurrences in the lowermost Famennian in western Canada. Ripidiorhynchus ? sp. bears some resemblance to Rhynchonella (Stenocisma) contracta ( Hall 1867: 351, pl. 55: 26–39) attributed by Linsley (1994) to Cupularostrum Sartenaer (1961b) .

Figures

Fig. 3. Brachiopod fauna of the shell bed in upper Hanover Shale Member of the Java Formation. A. Schizophoria (S.) sp. upper view of exfoliated ventral valve, NYSM 15701, × 1.7. B–D. Thiemella leonensis (Hall, 1867). B. Dorsal valve of juvenile specimen, NYSM 15722, × 4.6. C. Ventral valve, NYSM 15694,×2. D.Ventralviewofnearlycompleteshellextractedfrommoldiccavitytoleft,NYSM15699,×2.2.E, F. Ripidiorhynchus?sp. E.Upperviewofventralvalvewithplicaextendingfromanteriormargintobeakofvalve,NYSM15723,×2. F.Partialventralvalveshowingmedialandleftlateralflankplications, NYSM15724,×2. G. Chapinella?sp.,ventralvalvewithlateralplicationsnearshellmargin,NYSM15727,×2. H.Genusandspeciesuncertain,ventralvalve withradialplicaextendingfromanteriorandlateralmarginstobeakofNYSM15728,×4. I, J. Praewaagenoconcha speciosa (Hall,1867). I.Interiorofdorsal valve showing bilobed cardinal process, NYSM 15696, × 2. J. Upper view of ventral valve showing quincuncially arranged spines, NYSM 15697, × 2.