Siphonodella belkai Dzik. 1997 from Kowala andDzikowiec - P₁ elements.

Diagnoza

The dorsal( 'posterior') part of the platform of P₁ elements is completely smooth and convex, covered only with cell pits. The parallel arranged ridges end at the level of the cusp, the furrow between the blade and the posterior ridge continues to the tip of the platform. Free blade is short.

Porównanie

The only identified part of the apparatus are P₁ elements. They are very unusual, as for Siphonodella, in having smooth (except for fine reticulation produced by epithelial cells) and gently convex, anterodorsal flield of the platform. In juvenile specimens the first two ridges, that run strictly parallel to the carina, terminate abruptly at the level of the cusp and only immediately after the development of the ridges they merge with the platform margin. When additional ridges develop they tend to merge at their ends into pairs. Up to six ridges have been observed.

In a rather sudden narrowing of the platform at its ventral end, the elements resemble those of the type series of S. sandbergi, which may suggest common origin of these two species or even derivation of  S. belkai from American S. sandbergi, but in Polish sections no S. sandbergi has been found below the range of S. belkai. Moreover a population possibly corresponding morphologically to early S. sandbergi replaces S . belkai in the Kowala section.

Autekologia

Występowanie geograficzne

Kowala in the Holy Cross Mountains, Dzikowiec in the Sudetes,
Rzeczenice 1 borehole in West Pomerania.

Zasięg czasowy

Above S. duplicata, below
or partially together with S. carinthiaca.

Materiały muzealne

ZPAL

Literatura

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.