Gatunek typowy Mehlina irregularis Youngquist, 1945 from the late Frasnian Independence Shale (Amana Beds) of Iowa. Opis
Polygnathids with very flat P1 elements having extremely narrow basal cavity, inverted in later ontogeny, lacking platform; M elements with relatively short and transversely arranged inner process. The morphologic distinction between Pandorinellina and Mehlina is far from being apparent and it is further obliterated by their population variability. Nevertheless, these are branches of platform-lacking polygnathids separate already in the Frasnian and throughout their stratigraphic occurrence giving rise to several lineages of conodonts with platform- or icrion-bearing P1 elements. Even if practical application of their taxonomy may cause difficulties, it is reasonable to distinguish them at the generic level because of phylogentic consequences. 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. |