EVOLUTION AND SYSTEMATICS OF SEYMOURIAMORPH PARAREPTILES

Abstract

The data on the morphology, systematics, stratigraphy, and ecology of seymouriamorphs (Parareptilia) are revised. Cranial morphology of ten seymouriamorph species belonging to seven genera and three families from the Lower and Upper Permian of European Russia and Central Asia are described. According to the main evolutionary trends characteristic of this group, it is proposed to divide seymouriamorphs into the super-families Kotlassioidea and Seymourioidea. The evolution of kotlassioids, which were closely associated with aquatic habitats, predominantly consisted in the specialization of the dental system; the morphological features of this system provided the foundation for the systematics of the lower-rank taxa. The evolutionary development of seymourioids occurred against a background of adaptation to the semiaquatic biotopes.