Comments on the Squamation of Polish Lower Devonian Porolepiforms

Porolepiform scales from the Lower Devonian of the Holy Cross Mountains, Poland, described from the ‘placoderm sandstone’ of the Daleszyce area, are revised. The aim of the present article is to organize the recently collected, but not formally described, porolepiform material from the Holy Cross Mountains, as well as specimens from erratic boulders collected near Gdynia (northernmost Poland), which can be referred to Porolepis. Previously collected and new material was found to contain at least two sarcopterygian taxa: Porolepis and Heimenia. Based on morphological and histological features, the described material has been divided into two scale assemblages. The first, which is assigned to Porolepis, possesses cosmine cover on the entire exposed area; in the second, assigned to Heimenia, the cosmine cover is reduced or absent. These features prove to be stable regardless of the position of the scale on the body and thus are taxonomically informative