Volker Ebbighausen

Tournaisian and Viséan ammonoid stratigraphy in North Africa

Fifteen ammonoid assemblages can be distinguished in the Tournaisian and Visean succession of Morocco and Algeria; these are (in ascending order): Gattendorfia-Eocanites Assemblage, Gattendorfia-Kahlacanites Ass., Goniocyclus-Protocanites Ass., Acrocanites-Kazakhstania Ass., Pericyclus-Progoniatites Ass., Ammonellipsites-Merocanites Ass., lower Bollandites-Bollandoceras Ass., upper Bollandites-Bollandoceras Ass., Entogonites-Maxigoniatites Ass., Goniatites tympanus Ass., Goniatites rodioni Ass., Goniatites gerberi Ass., Dombarites granofalcatus Ass., Platygoniatites rhanemensis Ass., and Ferganoceras torridum Ass. Several of these faunal complexes can be subdivided into species zones, which can be correlated with ammonoid successions in other regions such as Central Europe. The new family Acrocanitidae is erected and placed in the Prionoceratoidea. Additional new taxa are Acrocanites smidensis n. sp., Jdaidites serpentinus n. gen. n. sp., Beyrichoceras merzougense n. sp., and Goniatites tympanus n. sp.

Conch geometry and ontogenetic trajectories in the triangularly coiled Late Devonian ammonoid Wocklumeria and related genera

The species of the genera Wocklumeria and Parawocklumeria are investigated in terms of their conch geometry, intraspecific variability, and ontogenetic trajectories using a rich material. Both genera are closely related, as indicated by a number of characters regarding conch geometry, ornament, and suture line. Some of the peculiar conch characters, including adult modifications, such as opening of the umbilicus, a terminal constriction, lateral narrowing of the mature aperture, and extreme septal crowding that is paralleled by the loss of suture characters can be seen in Wocklumeria. Wocklumeria sphaeroides (RICHTER, 1848) and Wocklumeria denckmanni (WEDEKIND, 1918) are distinguished on the base of degree of triangular coiling in intermediate whorls. Wocklumeria oblivia n. sp. and Wocklumeria boulmanensis n. sp. are newly described from the Anti-Atlas of Morocco.

Rare representatives in the ammonoid fauna from Büdesheim (Cephalopoda, Eifel, Late Devonian) and the role of heterochrony

Members of the genera Archoceras and Beloceras are very rare representatives in the ammonoid assemblage from the Frasnian (Late Devonian) Budesheim Shales. These two genera occupy a position at the margins of the morphological spectrum within the fauna; Archoceras is interpreted as a paedomorphic form characterised by a reduction in morphological complexity in conch shape and suture line, while Beloceras is characterised by an increasing complexity in conch shape and suture line.