New cranial material of Discosauriscus pulcherrimus (Seymouriamorpha, Discosauriscidae) from the Lower Permian of the Boskovice Basin (Czech Republic)

摘要

We describe four newly discovered and three-dimensionally preserved specimens of the discosauriscid seymouriamorph Discosauriscus pulcherrimus from the Lower Permian lacustrine sediments of the Boskovice Basin (Czech Republic). Their excellent preservation revealed new cranial features that allowed us to present a new skull reconstruction of middle-sized specimens of this tetrapod. The new features include: (1) the sculpturing of the anterior wedge-like process of the parasphenoid consisting of irregular ridges, grooves, low elevations and pits; and (2) the presence of a pair of semicircular crests on the posterodorsal surface of the parasphenoidal plate. We discuss the intraspecific variability of several characters, such as the type of dermal cranial ornamentation, and the morphology of the sensory grooves, nasolacrimal canal, dentition on the pterygoids and parasphenoid. The lengths of the skulls of four new specimens range from about 18 to 31mm and represent larval ontogenetic stages.