Cheiloceras inversum (Sobolew, 1912), from the C. marginifera Zone at Łagów-Dule in the Holy Cross Mountains.

Cheiloceras inversum; growth lines and internal thickening, thickenings, sutures and outline of the shell.

Diagnoza

Internal thickenings of the conch tending to develop ventral saddle; suture with variously developed blunt indentation in the flank lobe; relatively globose conch.

Porównanie

There was considered the presence and course of internal thickenings to be of much taxonomic importance. This view has not been generally accepted and the distribution of thickenings is known to be variable even within a single specimen. It is difficult to estimate the range of variability of the species because the material in my disposal may be heterogenous as it was collected mostly from loose blocks. In the collection of Otto Schindewolf housed at the Museum für Naturkunde in Berlin there is a sample probably coming from the same bed. There are 37 discoidal specimens probably representing Ch. lagoviense among them, 39 specimens with the ventral sinus of the internal thickening resembling what is here classified in Ch. pompeckji, 3 specimens with asymmetric course of thickenings, 17 with transverse thickenings, 19 specimens with a ventral saddle of the thickenings, and 29 specimens without thickenings. This is not consistent, however, with results of my collecting. In particular blocks specimens with clearly demarkated ventral saddle dominate, which seems to support taxonomic value of this character.

Autekologia

Występowanie geograficzne

Łagów-Dule.

Zasięg czasowy

C. quadrantinodosa and C. marginifera Zones. 

Materiały muzealne

ZPAL: 34 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.