Tympanotonos turris ( Deshayes, 1833 )

Islamoğğlu, Yeşşim, Dominio, Stefano & Kowalke, Thorsten, 2011, Early Eocene Caenogastropods (Mollusca, Gastropoda) from Haymana-Polatl Basin, Central Anatolia (Turkey): taxonomy and palaeoecology, Geodiversitas 33 (2), pp. 303-330 : 319

Tympanotonos turris ( Deshayes, 1833) ( Fig. 6H, I )

Cerithium turris Deshayes, 1833: 335 , pl. 35, figs 13, 14.

Potamides monsecanus – Cossmann 1896: 187, pl. 9, figs 18-20.

Potamides orengae – Cossmann 1896: 190, pl. 9, figs 15- 17.

Tympanotonos turris – Cossmann & Pissarro 1910: t. 2, 29, fig. 151/6.

MATERIAL EXAMINED. — One specimen, MTA- Y. İ.-2007 -53, from the early Ypresian of KIrkkavak Formation, Haymana-PolatlI Basin, Turkey.

LOCALITY AND HORIZON. — Grey siltstone-mudstone, KIrkkavak Formation (Macunköy: sample G2).

PALAEOGEOGRAPHIC DISTRIBUTION. — France: Early Ypresian (Early Eocene) ( Cossmann & Pissarro 1911).

DESCRIPTION

The medium-sized shell has a conical spire consisting of eight slightly concave whorls with incised sutures. Up to five spiral ribs are recognized in each spiral whorl, six in the body whorl. The crossing of axial ribs with the posterior and more pronounced spiral rib forms sharp, close, elongated spines, resulting in a strong shoulder and a steep angular outline. The anterior ribs bear smaller and indistinct nodes. Whorls rapidly increase in width, resulting in a turriculated spire. The body whorl is short with a flat base sculptured by six widely-spaced spirals, the anterior ones being slightly more pronounced than the intermediate, crossed by oblique S-shaped growth lines. The aperture is siphonostomatous.

REMARKS

This species has a characteristic conoidal and turriculate shape, angular outline and pronounced shell ornamentation. The single specimen collected in KIrkkavak have a more prominent posterior spiral rib with respect to the holotype figured by Deshayes (1833). However, the species is highly variable, as recognized by Deshayes and proven by a comparison with material from the type area in the Sparnacian of the Paris Basin (see for example sample number J02518 within a sample from Pourcy, Marne, housed at the MNHN). On the other hand of the spectrum are morphotypes with a higher spire and distantly-spaced spines and tubercules, ribs being as few as three in the spiral, four in the body whorl. Deshayes (1833) under- lines the similarities between “ Cerithium ” turris and C. papalis ( Deshayes, 1833) another species he described from the Cuisian (late Ypresian) type locality. The latter can be distinguished on the basis of more numerous, finely sculptured spiral ribs and a less tuberculate posterior ramp.

Figures

FIG. 6. — Caenogastropods (deposited in the repositories of the General Directorate of Mineral Research and Exploration, Ankara): A, Cerithium puigcercosensis (Cossmann,1897) n. comb.;B-F, Vicinocerithium cf.subacutum (d’Orbigny,1850); G, S, Bellatara ankaraensis n. sp., holotype;H, I, Tympanotonos turris (Deshayes,1833); J, Cerithium cf.anguloseptum Rauff,1884; K-M, Gantechinobathra vulcani (Brongniart, 1823); P-R, “Crommium” sp. 2. Scale bars: 1 cm.