Original paper

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

Ebbighausen, Volker; Korn, Dieter


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.


ammonoideawocklumerialate devoniantriangular coilingontogenybiometry