Opis

Diagnosis. — P1 elements with axial symmetry, bearing elaborate icrion or high-positioned platform.

Remarks. — The three Famennian conodont lineages with more or less developed axial symmetry in their platform elements probably share their common ancestry in a Pandorinellina-like form of early Famennian age. The Pseudopolygnathus lineage continued without any drastic morphological changes from the Famennian to the Tournaisian when it diversified significantly. Alternognathus is apparently only a homeomorph of Pinacognathus (sensu Dzik 1994) and early Siphonodella. Omolonognathus, known from the late Famennian of the Cracow area  may be an extremely shallow-water offshoot of the Alternognathus lineage. There is a continuity between the mid Famennian Scaphignathus and Tournaisian Clydagnathus lineages. It has to be admitted that there is some uncertainty whether the axial symmetry originated only once at the base of the whole clade. Whereas Pandorinellina seems to be truly the best root for the Alternognathus branch, the oldest member of the Pseudopolygnathus lineage (P. jugosus) shows expanded basal cone similar rather to Dasbergina stabilis, the species stratigraphically preceding the lineage of Pseudopolygnathus but not Alternognathus. The family defined as above may thus be polyphyletic.

Synonimy

Zasięg czasowy

Literatura

Dzik, J. 2006. The Famennian "Golden Age" of conodonts and ammonoids in the Polish part of the Variscan sea. Palaeontologia Polonica 63, 1-359.