Acta Palaeontologica Polonica

Gradual evolution of conodontophorids in the Polish Triassic

Jerzy Dzik and Jerzy Trammer

Acta Palaeontologica Polonica 25 (1), 1980: 55-89

A monospecific continuum of populations of the conodont genus Gondotella occurs in a 23 m thick limestone set at the AnisianlLadinian boundary in the southwest margin of the Holy Cross Mts, Poland. The change in distribution of morphological characteristics of the platform element is gradual and consists in an increase in contribution of morphologically juvenile stages to the fossil populations. Purely ecological interpretation of this trend as a continuous change in population dynamics is refuted. The trend reflects a true evolution. The other elements of the apparatus Gondotella do not undergo any significant changes, except possibly for the pt element ("Enantiognathus"). Time span separating fossil populations with non-overlapping standard-deviation ranges of diagnostic features sets actually the limit to recognition of temporal sUbspecies. This is also the limit to precision of biostratigraphic zonation based upon temporal taxa. It is here proposed to introduce a nomenclatorial difference between temporal and geographical (or biological) subspecies by Insertion of a dash between specific and subspecitlc names.

Key words: Triassic, conodonts, evolution, biostratigraphy, taxonomy.

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