Acta Palaeontologica Polonica

Pterobranchites Kozłowski, 1981- an aberrant graptolite?

Piotr Mierzejewski

Acta Palaeontologica Polonica 29 (1-2), 1984: 83-89

The periderm of Ordovician Pterobranchites antiquus Kozłowski, 1967 has been examined with SEM. Four components have been recognized within the thecal wall: outer lining, cortex, fusellum and inner lining. The cortex material is
composed of thick, straight, unbranched fibrils arranged in several layers as in cortical layer of the graptolite periderm. P. antiquus, previously referred to cephalodiscid pterobranchs, is identified as an aberrant graptolite of uncertain
taxonomic position.

Key words: graptolites, pterobranchs, ultrastructure, Ordovician, Poland.

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