Interspecific relation of some Upper Devonian polygnathid conodonts

Abstract

Specimens of Polygnathus brevis Miller & Youngquist varying in size were described under various specific names. The presented changes, which take place in the ontogenetic development of this species, allow to separate it from other species, in particular from Polygnathus normalis Miller & Youngquist. The new diagnosis of P. brevis comprises the characteristics of its adult forms, while that original one was based on a juvenile holotype. As shown by a review of the hitherto known specimens, the species P. brevis is short-ranged and restricted to the Palmatolepis gigas Zone.