Diagnoza

The oldest Dinodus syrnmetry transition series elements in the Dzikowiec section occur in sample Dz-6 and in the Muhua section 0.6 m above the base of the Tournaisian limestone. They differ from later elements of the same genus in not having any platform-like ridges at their bases; they thus probably belong to a new species. In samples Dz-6 andDz-66they ate associated with strongly asymmetric sp elements that were proposed by Ji et al. ( 1989) to represent a transition between S. duplicata and S.' lobata. These two species differ rather profoundly h the morphology of the basal surface of the sp elements but, if both really have the same apparatus composition, the idea of their evolutionary relationship would receive additional strength. This problem cannot be solved with the available data, so I have to take a rather arbitrary choice of matching the robust symmetry transition elements from sample Dz-6 with the robust Siphonodella sp elements co-occurring there, which are another kind of sp element included in this ear\y Dinodus apparatus. These are similar morphologicallly to homologous elements of Tater P fornicates but with an even wider platform. Only a few specimens have been found and this apparatus reconstruction is, in fact, very weakly substantiated.

The issue is even more complicated by the presence of yet another candidate among sp elements to be matched with Dirndus in the low diversity Muhua sample Mu-28. These are elements resembling S. duplicata morphology but much more primitive than those from the Dzikowiec sample, which are transitional to S. sulcata in the platform appearance. There are some problems with the oz location in this case as, along with a single large element of morphology fitting very well  Dirndus, there are several minute elements transitional in shape between elements attributed here to ,S. carinthiaca and those interpreted above as belonging to S. duplicata in the Muhua section. It is unlikely that these are juvenile elements that would later in their histogeny have developed the morphology of the Dinodus sp elements. Perhaps at this stage of evolution the lineages of Dinodus and Siphonodella, although having developed different apparatuses, did not differ in sp element morphology.

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.