Amorphognathus ordovicicus Branson & Mehl, 1933 from the Mójcza Limestone.

Apparatus of Amorphognathus ordovicicus Branson & Mehl, 1933.

Diagnoza

The ne elements with a long cusp dominating over the denticles, which occur in very low numbers, usually a single one on each process.

Porównanie

Only platform and hi elements were described by BRANSON and MEHL (1933) from the type locality. The identification of the species is based on the assumed conspecificity with populations studied by BERGSTROM( 1971) and ORCHARD (1980) . Some of the sp elements from the upperm ost part (Zalesie Formation) of the Mójcza section have an unbranched anterior process
associated with a very wide platform . This seems to be characteristic of the species although there are several other associated specimens which differ from the older ones of A. superbus only in a slightly less developed inner lobe of the posterior process and a shorter , slightly more twisted inner process. The difference is not great and is much obscured by the great population variability. All the associated ne element s from the marly part of the section have the cusp strongly dominating over a few associated denticles, which is the diagnostic feature of the species (BERGSTROM J971 ; ORCHARD
1980; SAVAGE and BASSETT 1985). Still some doubts remain whether this is enough to consider the se
Mójcza populations conspecific with the British ones and the zonal boundari es based on the evolution of Amorphognathus must remain tentative. The main reason for th is uncertainty is the very limited evidence on the population and ontogene tic variability of the ne elements . It is clear from the available material that ne elements in late Amorphognathus species changed significantly in their histogeny.

Autekologia

Występowanie geograficzne

Zasięg czasowy

Populations from the marly limestones of the Zalesie Formation in Mójcza are
assigned to the species with some hesitation . Undoubtedly conspecific with British ones are the populations from the Zalesie Formation in Zalesie and in Miedzygorz (in the latter locality well
preserved ne elements were found) .

Materiały muzealne

Literatura

Bergström, S.M. & Leslie S.A. 2010. The Ordovician zone index conodont Amorphognathus ordovicicus Branson & Mehl, 1933 from its type locality and the evolution of the genus Amorphognathus Branson & Mehl, 1933. Journal of Micropalaeontology 29, 73−80.

Dzik, J. 1994a Conodonts of the Mójcza Limestone. In: J. Dzik, E. Olempska, & A. Pisera. Ordovician carbonate platform of the Holy Cross Mountains. Palaeontologia Polonica 53, 43-128.