Cyrtospirifer hornellensis Greiner, 1957

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 : 198

Cyrtospirifer hornellensis Greiner, 1957

Fig. 4H, I .

Cyrtospirifer hornellensis ; Greiner 1957: 28–29, pl. 7: 1–5, 6 (not dorsal valve specimen on right−hand part of image of Yale Peabody Museum number 19435B), and 7.

Material.—Figured specimens NYSM 15691 and NYSM 15692.

Remarks.—The available specimens are consistent with the species as described by Greiner (1957: 29). It must be pointed out that Greiner (1957) illustrated at least two distinct genera under the name C. hornellensis . One of the two dorsal valves (his “larger, presumably gerontic, individual” of Yale Peabody Museum number 19435B) illustrated in his pl. 7 (fig. 6, right−hand specimen) represents a new genus, which will be described (Ma and Day personal communication 2001) from the lower Famennian of South China.

Cyrtospirifer hornellensis is about half the size (width), has a narrower sinus and fewer flank plications, and lacks the medial groove on the dorsal fold of the much larger Cyrtospirifer sulcifer ( Hall and Clarke, 1894) . That form serves as the nominal species for the lowest Famennian C. sulcifer Assemblage Zone of Dutro (1981: 80, figs. 2, 7). As defined, that zone spans the interval of the Canadaway Group, immediately above the Java Formation of New York. Cyrtospirifer sulcifer ( Hall and Clarke, 1894) is not a true Cyrtospirifer and is considered here a species of Pripyatispirifer Pushkin (1996) . According to Greiner (1957) his illustrated specimens of C. hornellensis were collected 140 feet (42.6 meters) below the top of the upper Frasnian Wiscoy Formation (now Java Formation) and overlying deposits of the lower Famennian “Casaseraga formation” (= Caneadea Formation of the modern nomenclature). Greiner portrays its upper range (see his fig. 4) as somewhere high in the lower Famennian. Thus far, our material represents its lowest Famennian occurrence directly associated with Lower Pa. triangularis Zone conodonts in the upper part of the Hanover Shale of eastern North America.

Figures

Fig. 4. Brachiopods from the shell bed in the Hanover Shale Member of the Java Formation. A–D. Retichonetes aff. S. obscurus Cooper and Dutro, 1982. A. Internal mold of dorsal valve, NYSM 15704 with low medial myophragm, simple sockets flanking the pit near base of cardinal process, × 5.4. B. Upper exteriorviewofdorsalvalve,NYSM15710,×4.8. C.Internalmoldofdorsalvalve,NYSM15705,×7. D.Ventralvalveshowingcostellaewithcrushedand distorted ventral valve of Ambocoelia cf. A. gregaria in upper left, NYSM 15718, × 3.3. E. Tylothyris mesacostalis (Hall, 1867), view of dorsal valve showing centric lamellose ornament and central groove on fold, NYSM 15711, × 2.3. F, G. Praewaagenoconcha speciosa (Hall, 1867). F. Internal mold of dorsal valve with impression of medial myophragm and rugae along the postero−lateral margin, NYSM 15706, × 1.7. G. External mold of dorsal valve showing radial spine bases with some exfoliated shell material, NYSM 15695, × 1.5. H, I. Cyrtospirifer hornellensis Greiner, 1957. H. Exfoliated dorsal valve showing extended postero−lateral extremity, NYSM 15692. I. Ventral valve, NYSM 15691; both × 1.8.J. Ambocoelia cf. A. gregaria Hall, 1867, upper view of flattened dorsal valve showing dorsal groove, NYSM 15719 × 3.5.