Archaeovenator

Abstract: Pyozia mesenensis, gen et sp. nov. is the second varanopid synapsid from the Middle Permian Kras- noschelsk Formation of Russia. Pyozia is a basal varanopid similar to Archaeovenator in having teeth that lack lateral compression or serration, lacking a caniniform tooth or region on the maxilla, and possessing four premaxillary teeth. Pyozia uniquely possesses a medial contact of the maxilla with the quadratojugal with no lateral exposure allowing the jugal to form part of the skull's ventral margin, and rounded interpterygoid vacuities just anterior to the basipter- ygoid articulations. Phylogenetic analysis places Pyozia as sister taxon to the terminal dichotomy of Mycterosaurinae and Varanodontinae. The newly described Upper Carboniferous Archaeovenatoris again found to be the most basal varanopid. The Permian saw a large-scale changeover of the synapsid fauna, with derived, but ecologically similar, taxa, re- placing more primitive ''pelycosaurs.'' Leaf-shaped tooth-bearing caseids were replaced in the Middle and Late Permian by herbivorous pareiasaurs with similar dentition, and Edaphosaurus was replaced by therapsids capable of processing plant material. The large predators of Sphenacodontidae were similarly replaced by therapsid predators. The small to medium sized predator niche, however, was continuously occupied by varanopids. The discovery of the basal Pyozia suggests that varanopids maintained their diversity in the Middle Permian.

Abstract: A new genus and species of varanodontine varanopid, Tambacarnifex unguifalcatus, is described on the basis of the greater portion of the postcranium and a closely associated partial left dentary from the Lower Permian (Wolfcampian) Tambach Formation, the lowermost unit of the Upper Rotliegend, of the Bromacker locality in the midregion of the Thuringian Forest near Gotha, central Germany. Tambacarnifex unguifalcatus can be distinguished from all other varanopids on the basis of unique features of its vertebrae and unguals. A cladistic analysis of Varanopidae resolves T. unguifalcatus as nested within the varanodontines as the sister taxon of Varanops in a terminal dichotomy, which in turn forms the sister clade of the terminal dichotomy Varanodon+Watongia. The position of Aerosaurus is unaltered from previous analyses as the basal taxon of Varanodontinae. Elliotsmithia, which has been assigned alternately to both the varanodontines and the mycterosaurines, is resolved as a member of the latter. Tambacarnifex unguifalcatus is, therefore, the only varanodontine known from outside of North America. Within the Mycterosaurinae clade Mycterosaurus and Mesenosaurus resolve as a terminal dichotomy with Elliotsmithia and Heleosaurus related as successive sister taxa. As in previous analyses, Archaeovenator retains its position as the basal taxon of Varanopidae. Tambacarnifex unguifalcatus was an apex predator in a unique, heretofore undocumented Early Permian paleoecosystem in which the vertebrates were highly terrestrial inhabitants of an upland terrestrial setting, and constituted an early stage in the evolution of the modern terrestrial vertebrate trophic system, with herbivores greatly outnumbering apex predators in diversity, abundance, and biomass.