Revision of the early tetrapod Obruchevichthys Vorobyeva, 1977 from the Frasnian (Upper Devonian) of the North-western East European Platform

Abstract

Species composition of the genus Obruchevichthys Vorobyeva, 1977, previously based on two specimens from the Upper Frasnian (Upper Devonian) of Latvia and Leningrad Region of Russia is revised. The precise locality of the latter specimen was considered by the author of this taxon as unknown. Archives recently found in collection and field research in the presumable locality allowed the rediscovery of this important locality along the Sondala River (east of the Leningrad Region). This provenance is furthermore supported by spectrometric testing. Despite the presence of several subadult features hindering its attribution by earlier authors to a separate taxon, new observations on its morphology revealed that several characters of the material from Russia significantly differ from those of the type specimen that resulted in its attribution to a new genus and species Weberepeton sondalensis gen. et sp. nov. These differences mainly consist in a number of lower jaw characters, such as relative size of marginal teeth, development rate of the adsymphysial plate, orientation of the precoronoid fossa, and dermal ornamentation.