Anatoma, Woodward, 1859

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 62

Anatoma sp. A

Figs 20 C–I

Material. The Højerup Member is represented by MGUH 33088, MGUH 33089, MGUH 33090 and an external mould without number in the collection of the Natural History Museum. The Cerithium Limestone Member is represented by MGUH 33091.

Occurrence. Lithified top of the Maastrichtian Højerup Member at Rødvig and the basal 10 centimetres of the Danian Cerithium Limestone Member at Højerup Church, corresponding to the foraminiferal zone Pα.

Description. Protoconch at least 0.3 mm in diameter, consisting of two smooth but angular whorls separated by distinct suture line. Selenizone peripheral, situated just above abapical suture. Teleoconch whorl more flattened with no angulation at wide selenizone. Adapical whorl surface covered by no or a few weak spiral ribs and fine, sharp, densely spaced prosocyrt transverse threads curving backwards towards selenizone; transverse threads numbering between 40 and 60 per whorl. Base of whorl typically covered by faint, very fine, densely spaced transverse threads and fewer faint spiral threads. Number of transverse threads approximately twice that of the transverse ribs on the adapical whorl side. Selenizone bordered by wide ridges.

Measurements. The largest specimen, MGUH 33088 is 1.3 mm in diameter and consists of three whorls.

Remarks. This taxon differs from Anatoma hedegaardi ( Bandel, 1998) and A. rosenkrantzi Schnetler et al., 2001 from the Danish middle Danian in a slightly more step-like shell, the typically marked increase in the number of transverse threads from adapical to abapical side of whorl and in the slightly wider selenizone.

Figures

FIGURE 20. A–B. Palaeoloxotoma sp., inner mould of MGUH 33087. Length 17.2 mm. C–I. Anatoma sp. A. C–E. Silicone casts of MGUH 33088. Width 1.3 mm. F–G. Silicone cast of MGUH 33089. Width 1.9 mm. H. Silicone cast of MGUH 33090. Preserved width 1.35 mm. I. Silicone cast of MGUH 33091. Preserved width 1.35 mm. J. Anatoma? sp. B, Silicone cast of MGUH 33092. Preserved width 1.05 mm. K–M. Temnotropis stevniensis n. sp. K–L. Silicone cast of holotype MGUH 33093. Width 3.5 mm. M. Umbilical view of paratype MGUH 33094. Width 2.1 mm. N–P. Leptomaria niloticiformis Schlotheim, 1820. N–O. Inner mould of MGUH 33095. Width 44 mm. P. Silicone cast of MGUH 33096. Middle Danian Coral Limestone from Faxe, Denmark. Height nearly 11 cm. Q. Leptomaria meyeri Pacaud, 2004. Silicone cast of MGUH 33097. Cast 14.5 mm wide, 12.5 mm high.