Acta Palaeontologica Polonica 25, 55-89 (1980).
Gradual evolution of conodontophorids in the Polish Triassic

Jerzy Dzik & Jerzy Trammer
Instytut Paleobiologii PAN, Twarda 51/55, 00-818 Warszawa, Poland. e-mail: dzik@twarda.pan.pl & Instytut Geologii Podstawowej UW, »wirki i Wigury 93, 02-089 Warszawa

Abstract. A monospecific continuum of populations of the conodont genus Gondolella occurs in a 23 m thick limestone set at the Anisian/Ladinian 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 of Gondolella do not undergo any significant changes, except possibly for the pl 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 (biological) subspecies by insertion of a dash between specific and subspecific names.