Pygodus anserinus Lamont & Lindstrom, 1957 from the Mójcza Limestone.

Diagnoza

The elements sp with four rows of tubercles, the oz elements with the angle between processes slightly smaller than right.

Porównanie

Relationships between these two species are the subject of some controversy FAHRAEUS (1982) claimed that there is an overlap in time ranges of P. serra and P. anserinus. He evidently defined these species vertically, all specimens with three rows of tubercles classified as P. serra while those with four as P. anserinus . One may argue, however, that in populations transitional between these chronospecies both these morphotypes must occur together. The overlap in their ranges would then be an artifactre sulting from the application of the typologic , instead of population , species concept. No population study on Pygodus has been performed yet and this precludes a more precise recognition of the evolutionary process. The material from the Mójcza Limestone is too scarce to solve the problem. Nevertheless, it is evident that the evolutionary introduction of the fourth row of tubercles was rather smooth, with widening of the area between two neighbouring rows preceding insertion of the new one. Initially the tubercles of the fourth row devel oped quite late in the histogeny of the element and in the course of evolution they started to develop closer and closer to the cusp . Although there are some differences in the orientation of processes in the oz e lements of these two species of Pygodus (BERGSTROM 1971) this is far from being apparent in the Mójcza material. The great population variability makes this feature useful taxonomically only if numerous oz elements are available.

Autekologia

Występowanie geograficzne

Mójcza

Zasięg czasowy

In Mójcza the species occurs from 1.0 m below to 0.2 m above the bentonite
(with the first Baltoniodus variabilis)

Materiały muzealne

Literatura

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