Acta Palaeontologica Polonica

The ammonite Acrochordiceras in the Triassic of Silesia

Jerzy Dzik

Acta Palaeontologica Polonica 35 (1-2), 1990: 49-65

A new specimen of Acrochordiceras from the Pelsonian of Strzelce Opolskie, Poland, and the holotype of Silesiacrochordiceras damesi (Noetling, 1880) are described. Ontogenetic changes in shell morphology, based on studies of museum specimens from the Gulf of Ismid, Turkey, are also presented. The pattern of temporal changes in the morphologic variability oi acrochordiceratids suggests that they many represent a single lineage, with posslble eexual dimorphism expressed in a degree of involuteness of adult specimens. It is proposed to subdivide the lineage into five succesive chronospecies of a single genus. Attribution of the specimen from Strzelce Opolskie to A. ippeni Arthaber, 1911 is proposed.

Key words: Triassic, ammonites, Ceratitida, Muschelkalk, Poland, phylogeny.

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