Nabelkanten-präferenz der formaverticata hölder 1956 bei dactylioceraten (ammonoidea, toarcien)

With the aid of new finds of anomalous ammonoids from the Franconian Jura, the phenomenon of the “Rippensdieitelung” is again discussed. Duplication of the keel in connection with “sculptural compensation” is represented as a new type of regeneration (forma duplicarinata n. f.). Two anomalies are defined as probable attacks of parasites and are called forma inflata n. f.