Tylostoma, Sharpe, 1849

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 102

Tylostoma ? sp.

Fig. 26N

Material. MGUH 33172 and a fragmentary internal mould in the same sample.

Occurrence. The lower Danian ‘dead layer’ in Dania Quarry, Northern Jutland.

Description. Shell large, strongly rounded in outline with a low spire and spire whorls. The most complete specimen MGUH 33172 shows signs of an internal raised band just abapical of periphery. Aperture moderately narrow with no sign of teeth or varices on outer lip or parietal region.

Remarks. The material is very fragmentary and does not allow for a confident generic assignment, but it shows a strong resemblance to Tylostoma , and here especially the middle Danian T. ampullariaeforme Ravn, 1902 from Denmark. It differs from this species by having a lower spire and a narrower aperture.

Figures

FIGURE 26. A–B. Alvania sp. A. Silicone cast of MGUH 33164. Width 1.5 mm. C. Alvania sp. B. Silicone cast of MGUH 33165. Width 0.8 mm. D. Zebina sp., Wax cast of MGUH 33166. Width 0.9 mm. E–H. Ceratia rodvigensis n. sp. E–F. Silicone cast of holotype MGUH 33167. Width 0.8 mm. G–H. Silicone cast of paratype MGUH 33168. Width 0.9 mm. I–J. Ceratia? sp. I. Mould of MGUH 33169. Width 0.9 mm. J. Silicone cast of MGUH 33170. Height 1.1 mm. K. Anchura sp., Silicone cast of MGUH 33171. Width 8.6 mm. L–M. Columbellaria tuberculosa (Binkhorst, 1861). Silicone cast of ØSM.10042-202-a–c. Width 5.2 mm, height 5.9 mm. N. Tylostoma? sp., inner mould MGUH 33172. Width 19.9 mm. O–P. Cassidae genus et sp. indet. Silicone cast and internal mould of ØSM.10042-315-a–b and c, respectively. Width 9.2 and 8.6 respectively. Q–U. Sassia faxense Ravn, 1933. Q. Detail of apex of MGUH 33173. Width of protoconch 1.4 mm. R. Silicone cast of MGUH 33174. Width 6.0 mm. S. Silicone cast of MGUH 33175. Width 6.5 mm. T. Silicone cast of MGUH 33176. Width 7.8 mm. U. Silicone cast of MGUH 33177. Width 5.2 mm. V–X. Hipponix sp. V–W. Internal mould MGUH 33178. Length 23.8 mm, width 19.5 mm. X. Inner mould MGUH 33179. Width 19.1 mm. Y–Z. Eulima? danica Ravn, 1933. Y. Silicone cast of MGUH 33180. Width 2.5 mm. Z. Silicone cast of MGUH 33181. Width 2.0 mm. AE. Eulima? sp., Mould MGUH 33182. Width 1.3 mm.