Turritella cf. plana Binkhorst, 1861

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 84

Turritella cf. plana Binkhorst, 1861

Figs 23 V–W

Material. MGUH 33134 and a fragmentary teleoconch mould lacking number, which is stored in old collections at the Natural History Museum of Denmark.

Occurrence. Lithified top of the Maastrichtian Tor Formation at Stevns Klint.

Description. Whorls flattened, rectangular in cross-section with sharp peripheral transition to relatively flat base. Periphery of preceding whorl reaching slightly farther out than top of succeeding one, divided by fairly deep suture. Lower half of whorl with wide and shallow spiral furrow, separated from abapical suture by broad spiral band taking up just over a quarter of the whorl height. Aperture widened with the parietal lip slightly raised. Whorl surface covered by weak spiral lirae and indistinct, sharply sigmoid growth lines.

Measurements. The most complete specimen, MGUH 33134, measures 17.2 mm in diameter and has a last whorl height of 17.8 mm.

Remarks. The material is too fragmentary for a confident identification, but the taxon shows a close resemblance to the contemporaneous Turritella (Haustator) plana Binkhorst, 1861 from Belgium to which it is tentatively assigned.

Figures

FIGURE 23. A. Arene jakobseni n. sp., Silicone cast of paratype MGUH 33120. Preserved width 8.9 mm. B–E. Ataphrus (Ataphrus) knoesensis n. sp. B–C. Silicone cast of holotype MGUH 33121. Width 4.0 mm. D. Silicone cast of paratype MGUH 33122. Width 4.2 mm. E. Silicone cast of paratype MGUH 33123. Width 3.9 mm. F–H. Cerithium sp. F. Silicone cast of MGUH 33124. Width 10.7 mm. G. Silicone cast of MGUH 33125. Width 9.9 mm. H. Silicone cast of MGUH 33126. Width 10.7 mm. I. Pseudovertagus? sp., Silicone cast of MGUH 33127. Width 1.6 mm. J–K. Striovertagus? sp., Silicone cast of MGUH 33128. Width 2.5 mm. L–O. Cerithidea? sp. L–M. Silicone cast of MGUH 33129. Cast height on figure L 7.4 mm. Cast width on figure M 3.3 mm. N–O. Silicone casts of MGUH 33130. Width 3.7 mm. P–S. Cirsocerithium crassilabris (von Koenen, 1885). P–Q. Silicone casts of MGUH 33131. Width 5.0 mm. R. Lectotype MGUH 865. Upper Palaeocene Lellinge Greensand, Denmark. Height 12.7 mm. Photograph by S. L. Jakobsen. S. Lateral view of MGUH 33132. Upper Palaeocene Lellinge Greensand, Denmark. Width 4.4 mm. T–U. Turritellid genus et sp. indet, Silicone cast of MGUH 33133. Width 1.0 mm. V–W. Turritella cf. plana Binkhorst, 1861. Silicone cast of MGUH 33134. Whorl width at least 17.2 mm. Height of last whorl 17.8 mm. X–Y. Mesalia danica n. sp. X. Silicone cast of holotype MGUH 33135. Width 2.2 mm. Y. Silicone cast of paratype protoconch MGUH 33136. Width 0.7 mm. Z. Mesalia sp., Silicone cast of MGUH 33137. Width 0.6 mm. AE. Tenagodus sp., Silicone cast of MGUH 33138. Width 4.3 mm.