Natural assemblages of Palmatolepis from the Upper Devonian of the northern Urals

Abstract

Two bedding-plane assemblages from the Upper Devonian (lower Famennian, Upper triangularis Zone) of the Evtropiny Noski section on the Unya River in the northern Urals are of extraordinary significance for the controversial question of the structure of the Palmatolepis apparatus. The assemblages indicate that some species of Palmatolepis were characterized by nothognathellan (Pb), palmatodellan (M), smithiform (Sc), falcodontan (Sb), and asymmetrical (Sb) and symmetrical (Sa) scutulan elements, in addition to the platform (Pa) element. Thus, earlier views based on fused clusters and statistical analysis are reinforced by the discovery and description of the Unya River specimens. Palmatolepis is used as the generic name, because Palmatodella is a nomen dubium.