Diagnoza

The platform elements in the population represented by samples Dz-14 (S end of the quarry in Dzikowiec) andDz-2l (N end) are rather variable in ornamentation of their occlusal surfaces. In specimens mature enough to be determinable, the posterior rostral ridges continue much above the level of the cusp (basal pit), almost half of them being sinusoidally curved and reaching the posterior margin asymptotically. In numerous specimens, however, the ridge curves posteriorly meeting the platform margin at a high angle: the pattern typical of populations occurring below and above in the Dzikowiec section. Unlike the older populations, the concave central part of the platform is  ornamented by at least weakly developed transverse ridges or, rarely, by tubercles. It remains possible that the observed differences between the Dz-50 andDz-14 populations are just a result of an intraspecific variabiJity, which is very wide in both cases. I am not able to prove it biometrically because of problems with quantifying the diagnostic characters, which are also not easily discernible using light microscopy.

Specimens with a narrow unribbed central part of the platform occur in the youngest productive sample of the Kowala section, Ko-21 (Fig. 19O), and may be conspecific with these Dzikowiec populations.

Only a few ramiform elements that can be matched with these platform elements have been found. The oz elements are of morphology similar to those occurring below in the section except for much stronger transverse ridges at the basal cavity, giving the element a cruciform appearance when seen occlusally. The hi elements (if correctly identified) do not differ significantly from those attributed to other species of the genus.

Exactly the same element morphology that dominates among mature elements in the Dzikowiec population seem to characterize the type population of Siphonodella obsolete from sample9 301 taken 2.5-3.0 m below the top of the Chappel Limestone at the Barton Ranch section in Mason County,Texas. The holotype (Hass 1959: pl. 47:2) seems to be a typical member of its population represented by 52 specimens co-occurring in a low diversity assemblage with much more numerous Gnathodus punctcttus Cooper, 1939. However, the currently accepted time correlation between  American and European sections makes this taxonomic identification unacceptable, as was also the  case with the preceding species.

Porównanie

Autekologia

Występowanie geograficzne

Zasięg czasowy

Materiały muzealne

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.