Diagnoza

The blade of P₁ elements straight in profile view or gently convex, with the cusp not separated from other denticles or slightly higher but almost straight.

Porównanie

The early form of Pelekysgnathus planus from the earliest Famennian shows a linear profile of the blade with a weak denticulation and the cusp not separated from other denticles, similarly as in the Frasnian (Dzik 2002). In samples of somewhat younger age, for instance J-53a , along with such specimens a new morphology emerged, with a dominant cusp and sharp, separate denticles. The blade remains short, however, which only partially results from generally small size of elements. In later (typical) forms with a gently inclined cusp, the profile of the blade is convex, similar as in the holotype (Sannemann 1955a). Mature robust elements show a weak denticulation. Associated non-platform elements (e.g., J-03) represent two separate classes of triangular elements (probably P₂) wider than in Icriodus alternatus and more robust needle-like elements.

Autekologia

Występowanie geograficzne

Continues from the latest Frasnian to the C. marginifera Zone (Ł-13); specimens from the P. jugosus Zone at Ostrówka are probably reworked.

Zasięg czasowy

Materiały muzealne

1,113 specimens. ZPAL

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.