spine with a rounded dorsal margin in lateral view. Using outgroup comparisons, the morphology of the transverse processes is considered a derived trait in varanodontines, while in mycterosaurines the morphology of the axial spine is the derived trait. Ecology At least some varanopids like Ascendonanus and Eoscansor are amongst the oldest known tree climbing (arboreal) animals, with limbs and digits adapted for grasping. Other varanopids lacked these adaptations and were probably terrestrial. Classification Family Varanopidae Apsisaurus Archaeovenator Ascendonanus Basicranodon (possible junior synonym of Mycterosaurus) Eoscansor Dendromaia Pyozia Thrausmosaurus? (nomen dubium) Clade Neovaranopsia Subfamily Mesenosaurinae Cabarzia Mesenosaurus Clade Afrothyra Anningia Elliotsmithia Heleosaurus Microvaranops Subfamily Varanodontinae Aerosaurus Mycterosaurus Ruthiromia Tambacarnifex Varanodon Varanops Watongia Apsisaurus was formerly assigned as an "eosuchian" diapsid. In 2010, it was redescribed by Robert R. Reisz, Michel Laurin and David Marjanović; their phylogenetic analysis found it to be a basal varanopid synapsid. The cladogram below is modified after Reisz, Laurin and Marjanović, 2010. The poorly known Basicranodon and Ruthiromia were tentatively assigned to Varanopidae by Reisz (1986), but have been neglected in more recent studies. They were included for the first time in a phylogenetic analysis by Benson (2012). Ruthiromia was found to be most closely related to Aerosaurus. Basicranodon was found to be a wildcard taxon due to its small amount of known materials, as it is based on a partial braincase from the ?Kungurian stage Richards Spur locality in Oklahoma. It occupies two possible positions, falling either as a mycterosaurine, or as the sister taxon of Pyozia. Although Reisz et al. (1997) considered Basicranodon as a subjective junior synonym of Mycterosaurus, Benson (2012) found some differences in the distribution of teeth and shape of the dentigerous ventral platform medial to the basipterygoid processes that may indicate taxonomic distinction. Below is a cladogram modified from the analysis of Benson (2012), after the exclusion of Basicranodon: References External links Varanopseidae - at Palaeos Pennsylvanian first appearances Guadalupian extinctions Prehistoric synapsid families Taxa named by Llewellyn Ivor Price Taxa named by Alfred Romer