Abstract: The theories of the origin of coiled ammonoids are discussed by examining
       former statements in favour or against a derivation from coiled nautiloids
       (SPATH) or from bactritids (ScHINDEWOLF), respectively.  Results of additional stadies
       indicate an ancestorship of the Bactritidae.  Evidence is represented by homologies of
       morphological elements of the shell, by the similarity of the early ontogentical develop-
       ment, by a progressive evolutionary succession of species and genera connecting primitive
       goniatites with the Bactritidae, and by iterative as well as regressive tendencies indicating
       relationsbp.
            The evolution of early Ammonoidea (including the Bactritidae) is studied.  The main
        evolutionary succession leading from bactritids to coiled ammonoids seems to be:
        Bactrites - Lobobactrites - early Cyrtobactrites - Anetoceras hunsrueckianum  - A. aff.
hunsrueckianum - A. (Erbenoceras) sp. A. - Teicherticeras (?) n. sp. B - (?early
Convoluticeras) - zorgensis-group of Mimagoniatites-obesus group of Mimagoniatites -
Anarcestes - Anarcestidae without umbilical opening - other groups of Ammonoidea.

The original note is cut because of overlengh of text. Full text of note in:

Neus Jahrbuch Geologie und Paläontologie, Abhandlungen, vol.120, p.108, Stuttgart 1964.