Typically, they are considered to be relatively basal synapsids (and thus more closely related to mammals than to reptiles), although some studies from the late 2010s recovered them being taxonomically closer to diapsid reptiles,[1][2][3] recent studies from the early 2020s support their traditional placement as synapsids on the basis of high degree of bone labyrinth ossification, maxillary canal morphology and phylogenetic analyses.

Compared to the other animals in Early Permian, varanopids were agile creatures.The genus Ascendonanus provides the first extensive skin impressions for ancient amniotes, revealing scales akin to those of squamates.

Most phylogenetic analyses have place Varanopidae as a basal member of Synapsida and due to their positioning, a better understanding of the morphology and phylogeny of varanopids is needed for synapsid evolution.

The larger varanodontine varanopids have large transverse processes with a broad base, and a much taller axial spine with a rounded dorsal margin in lateral view.

[18] Archaeovenator Apsisaurus Mesenosaurus Mycterosaurus Varanodontinae The poorly known Basicranodon and Ruthiromia were tentatively assigned to Varanopidae by Reisz (1986), but have been neglected in more recent studies.

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.

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.