Polygnathus extralobatus Schäfer, 1976 from the P. jugosus Zone at Ostrówka and Jabłonna in the Holy Cross Mountains, Gołogłowy and Dzikowiec in the Sudetes.

Diagnoza

Widened dorsal part of the platform in P₁ element covered with obliquely running transverse ribs, discontinuous near the carina.

Porównanie

The species is so close to its stratigraphic predecessor, P. obliquicostatus Ziegler, 1962 that the ancestor-descendant relationship between them seems almost certain. That species has not been encountered in the material available to me so the lineage probably entered the Holy Cross Mountains after the widening of the platform lobe was completed. P. semicostatus seems to be a likely ancestor of P. obliquicostatus.

Autekologia

Występowanie geograficzne

Kowala, Jabłonna, and Gołogłowy.

Zasięg czasowy

P. jugosus and D. trigonica Zones. 

Materiały muzealne

ZPAL: 1014 specimens.

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.