Tylothyris mesacostalis ( Hall, 1867 )

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

Tylothyris mesacostalis ( Hall, 1867)

Fig. 4E .

Spirifer mesacostalis ; Hall 1867: 240, pl. 40: 1, 2, 4–13; Hall and Clarke 1894: 16, 35, pl. 34: 32–34.

Tylothyris mesacostalis ( Hall, 1867) ; Cooper 1944: 321–322, pl. 122: 20, 21; Linsley 1994: 234, pl. 127: 6–20.

Material.—Figured specimen NYSM 15711, and approximately 180 additional unnumbered specimens on parts and counterparts of split slabs.

Remarks.—This is a long ranging species in the Late Devonian of New York. It is the nominal species of Dutro’s (1981: 78, figs. 2, 7) middle Frasnian Tylothyris mesacostalis Assemblage Zone. Its range in the New York Upper Devonian is shown to begin in the upper part of the Sonyea Group (mid Frasnian) and terminates in the Conneaut Group at the top of the interval of Dutro’s (1981: figs. 2, 7) Famennian Spinulicosta arctirostrata Assemblage Zone.

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.