Icriodus expansus Branson & Mehl, 1938 from the Early Frasnian of Wietrznia and Włochy  P₁ (sp) elements.

Diagnoza

This oldest Frasnian Icriodus, well represented in sample Wtr-8, is characterised by a primitive drop-like contour of the icrion, with sharply pointed dorsal end. It became less pointed in adult specimens, but even in robust large forms (common in samples Wtr-7 and Wtr-10) the drop-like contour remains. In juvenile specimens denticles of the middle row are of virtually the same height as those of the side rows, later in the ontogeny the medial denticles fuse in the middle part of the element and rise above the rest of the icrion. Whether this population is truly conspecific or not with the type population of I. expansus from the Mineola Limestone of Missouri, requires population studies. Associated ramiform elements are of extremely simple morphology and it is hard to tell which of them are complete elements and which are disassociated denticles of processes with unmineralised bases.

Porównanie

Autekologia

Występowanie geograficzne

Zasięg czasowy

Materiały muzealne

Literatura

Dzik, J. 2002. Emergence and collapse of the Frasnian conodont and ammonoid communities in the Holy Cross Mountains, Poland. Acta Palaeontologica Polonica 47 (4): 565-650