A Santonian record of the nautilid cephalopod Angulithes westphalicus (Schlüter, 1872) from the subsurface of the Campine, north-east Belgium, with comments on regional lithostratigraphic problems

Newly recognised material of the Late Cretaceous nautilid Angulithes westphalicus (Schlüter, 1872) is described from the subsurface of the eastern part of the Campine in north-east Belgium. This constitutes the first formal documentation of this genus and species from the Cretaceous of Belgium, having been identified amongst a large suite of fossils collected from the Voort Shafts I & II of the Zolder colliery during the first half of the twentieth century. The specimens originate from an interval of marine calcareous sand with a marly glauconiferous base, dated as late middle Santonian (Gonioteuthis westfalicagranulata belemnite Zone) and for which a deepening of the depositional environment is documented. Lithostratigraphically, the specimens occur within the Vaals Formation, within the upper part of the Asdonk Member or alternatively within the lower part of the Sonnisheide Member. The early Campanian age of the Asdonk Member suggested previously is refuted, the age of the Sonnisheide Member needs further study. The position of the siphuncle in A. westphalicus is illustrated for the first time; it is positioned closer to the venter than the dorsum, which confirms the close evolutionary relationship with Angulithes galea (Fritsch in Fritsch & Schlönbach, 1872), which ranges from the upper Turonian to middle Coniacian in central Europe.