Neopolygnathus communis (Branson & Mehl, 1934) from the C. quadrantinodosa Zone at Łagów, the early L. styriacus Zone at Ostrówka, the P. trachytera Zone at Kowala, the late L. styriacus and the P. jugosus Zones at Ostrówka in the Holy Cross Mountains.

Neopolygnathus communis - P₁ element.

Diagnoza

Margins of the platform of P₁ elements raised adorally, with more or less distinct longitudinal crests in its ventral area; only in extreme specimens tuberculation of various kinds may develop.

Porównanie

Populations of a narrow-platform form of N. communis from the K. crepida Zone are ancestral to a clade of variously ornamented forms united only by their depressed basal pit. I am inclined rather to the alternative interpretation, that the separation of pre-platform stage from the fast growing platform marginally is rather a developmental aspect not requiring fundamental change in controlling mechanisms and thus appearing independently in unrelated lineages. This may be only an expansion of the larval stage (sinuosa larva), poorly controlled by developmental regulatory mechanisms, as suggested by great population variability in early populations. The range of variability includes forms with narrow and wide platforms, completely smooth and ornamented with transverse ridges, without any crests, bearing crests parallel to the blade or at an angle to it. This morphologic lability ceases in the latest Famennian, where a morphologic gap develops between N. communis and N. vogesi.

Autekologia

Występowanie geograficzne

Łagów, Jabłonna. 

Zasięg czasowy

C. quadrantinodosa Zone; C. marginifera Zone.   

Materiały muzealne

ZPAL:1,447 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.