Acta Palaeontologica Polonica

Remarks on the evolution Of Ordovician conodonts

Jerzy Dzik

Acta Palaeontologica Polonica 21 (4), 1976: 395-453

The phylogeny of Ordovician Conodontophorida from the Baltic region is reconstructed and homologization of elements of the natural assemblages is presented. A reconstruction of the apparatus of Spathognathodontidae indicates that it was a bilateral medial organ composed of 14 conodonts with dentides turned inwards. Attempts are made to homologize the tissue of conodonts Panderodontidac with enamel of dermal dentides of lower Ve,tebrata and the basal filling tissue with dentine. A common phenomenon in conodont evolution is the occurrence of morphological gradient within the apparatus. The evolutionary changes are introduced polarly, and successively spread from the most rapidly evolving element on the adjoining ones. Fifty six species and subspecies of Ordovician conodonts are illustrated and their synonymes given. Two new suborders, three genera, seven species and three temporal subspecies are proposed.

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