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. They differ from those of other species by the almost parallel and strongly bent platform margins and by the depression in the lower surface immediately dorsal (posterior) of the pit. The platform is smooth except for singular knobs constricting the central concave area of the platform from both sides; only in extreme specimens tuberculation of various kinds may develop. The P₂ elements are distinct from the related species and easily distinguishable on the basis of a clearly separated cusp, much larger than other denticles.

Porównanie

This is an extremely long ranging species. In the Tournaisian it may occur sympatrically with three other closely related species  that do not show any morphological transitions and thus are obviously biologically distinct: N. purus, N. vogesi, and N. biconstrictus. Populations of a narrow-platform early 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.  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, Ostrówka, Kowala, 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.

Dzik, J. 1997. Emergence and succession of Carboniferous conodont and ammonoid communities in the Polish part of the Variscan sea. Acta Palaeontologica Polonica 42, 57-170.