Apparatus composition of Pseudopolygnathus primus

Pseudopolygnothus primus (Branson & Mehl, 1934) from the Toumaisian Wapnica beds of Dzikowiec and Kowala.

Diagnoza

The P₁ elements of this species are characterised by an occlusal area ornamentation of the icrion type, with lateral denticles of the same height as those of the main row of the blade and connected with them by transverse ribs.

Porównanie

Juvenile specimens are of P. ('Bispathodus') costatus morphology, adults are still narrow, with a long smooth furrow separating the posterior row of denticles (there is rather a platform than icrion at this side of the element). Early populations contains only elements with the icrion developing on one side of the blade even in large specimens. In younger ones, the P₁ elements are more robust at comparable stages and more triangular in appearance. This may reflect some
evolutionary change but the great population variability and relatively small sample sizes do not allow one to document it biometrically.
The populations of the species strongly differ in P₁ elements morphology from those of the lineage of W. inaequalls, which co-occur with them partially. No
intermediate between them has been identified despite a high population variability. The younger populations of Pseudopolygnathus show much lower population variability and have generally a more primitive appearance. This may result from a species distinctness or from character displacement, an influence of the related Weyerognathus lineage.

Autekologia

Występowanie geograficzne

Missouri, the Sudetes

Zasięg czasowy

Tournaisian

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.