Varanops

Abstract: Description of the first varanodontine varanopid material from the highly fossiliferous limestone fissure fill deposits at Richards Spur (Dolese Brothers Limestone Quarry), Oklahoma, is based on elements of at least three individuals recovered from two separate blocks of sedimentary rock. One block, which yielded associated cranial and postcranial bones from both adult and juvenile individuals, includes two well-preserved parabasisphenoid complexes, vertebrae, forelimb, pelvic girdle, and hind limb bones. An isolated maxilla fragment from another block preserves the diagnostic dorsal process characteristic of varanodontines. Preserved cranial and postcranial material is virtually identical to the varanodontine Varanops brevirostris. Taxonomic assessment of this new material in the context of the most comprehensive phylogenetic analysis of Varanopidae to date indicates the Richards Spur varanodontine is referable to Varanops brevirostris based on distinctive characters of the maxilla and the parab...

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.

Abstract: The Texas red beds represent one of the richest series of early Permian deposits in the world. In particular, the Clear Fork Group has produced a diverse assemblage of temnospondyls, early reptiles, and synapsids. However, most of this material has been sourced from the oldest member, the Arroyo Formation, and the understanding of the paleoecosystem of the younger Vale and Choza formations is less well resolved. Here we present a previously undescribed Vale locality, the first vertebrate-bearing locality from the formation to be described in detail in several decades, from near Abilene, Texas with juvenile diplocaulids, captorhinids, abundant material of rare taxa such as Varanops and diadectids, and the first report of a recumbirostran ‘microsaur’ from the formation. This assemblage is atypical of early Permian deposits in the taxonomic and size distribution of the vertebrate fauna in comparison to other localities from the Vale Formation that preserve a greater abundance of aquatic taxa (e.g., fishes, Trimerorhachis) and synapsids (e.g., Dimetrodon). Minimal abrasion of the elements, relative articulation and association of the specimen of Varanops, and the paucity of aquatic taxa suggest an ephemeral pond deposit in which organisms were preserved essentially in situ. Our characterization of the locality also permits a revision and discussion of the vertebrate faunal assemblage of the Vale Formation.