Mid Famennian icriodontid Icriodus cornutus Sannemann, 1955 from Kadzielnia in the Holy Cross Mountains. Specimens from the K. crepida Zone sample Ka-2 - P₁ and sample Ka-14- P₂.

Diagnoza

Cusp of P₁ element inclined dorsally, narrow icrion of P₁ elements with irregularly distributed denticles of the middle row, which are sometimes slightly higher than those of lateral rows; in mature specimens they merge to produce irregular transverse ridges.

Porównanie

Autekologia

Występowanie geograficzne

At Jabłonna, the lineage of Icriodus reappears with this species after a gap in occurrence, when Pelekygnathus was the dominant icriodontid; in Kadzielnia there seems to be a continuity between I. alternatus and I. cornutus within the K. crepida Zone. Transitional samples show a great population variability, with specimens of morphologies similar to holotypes of I. alternatus, I. cornutus, and I. costatus occurring together. In samples J-65 and Ka-14 robust P1 specimens similar to the holotype of Icriodus costatus (Thomas, 1949) from the late Famennian Maple Hill Shale at Burlington, Iowa (Klapper in Ziegler 1975) are associated with equally robust non-platform elements ornamented with longitudinal striae. Robust P1 elements of this species somewhat resemble those of the Carboniferous Eotaphrus and perhaps this may be their more appropriate generic affiliation.
Rare specimens from the P. trachytera Zone are probably reworked. Icriodus apparently did not survive C. marginifera in the Holy Cross Mountains area, but I. chojnicensis Matyja, 1972 from Pomerania and the Lublin area (Matyja 1972, 1993; Matyja and Żbikowska 1974) may be a continuation of the lineage in marginal parts of the Variscan basin. 

Zasięg czasowy

Materiały muzealne

2,104 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.