Nannoceratopsis senex Van Helden, 1977

Holotype: Van Helden, 1977, pl.33.1, figs.6-7
Locus typicus: Panarctic Emerald Well K-33, Emerald Island, Arctic Canada
Stratum typicum: ?Late Pliensbachian-Early Bajocian

Original diagnosis: Van Helden, 1977, p. 165
A species of Nannoceratopsis having a distinctly rounded, ovoid outline, being dorso-ventrally more or less symmetrical, with a nearly smootn to microreticulate or scabrate surface.
Description. Lateral outline distinctly rounded to ovoid. Ventral side smoothly curved. A dorsal antapical horn with a finely pointed end is usually well developed. Ventral antapical horn absent. Surface sculpture microreticulate or scabrate to nearly smooth. Paracingulum and a small precingular area visible in some specimens. Other features as for genus.

Affinities: Van Helden, 1977, p. 165
This species differs from Nannoceratopsis gracilis and all other known species ol the genus in possessing an extremely rounded outline, both dorsally and ventrally, with only the dorsal antapical horn (well) developed, and in the reduction or absence of the ornamentation (reticulation) on its surface that is characteristic for N. gracilis. Nannoceratopsis senex Iacks a ventral antapical horn, which distinguishes it from N. pellucida and from N. spiculata.

Poulsen 1996 p.54 Pl. 40, Fig. 2, Pl. 36, Figs. 1-2
Remarks. The specimen attributed to Nannoceratopsis cf. senex by Dybkjaer (1991, p. 30, pl. 15, fig. 9) is here regarded as belonging to N. senex.
Recorded occurrences. Denmark: L. spinosa Zone, Subzone a to top? of Nannoceratopsis gracilis Superzone.