Varanidae


The Varanidae are a family of lizards in the superfamily Varanoidea. The family, a group of carnivorous and frugivorous lizards, includes the living genus Varanus, the extinct Megalania, and a number of other extinct taxa. Varanus includes the Komodo dragon, crocodile monitor, savannah monitor, the goannas of Australia and Southeast Asia, and various other species with a similarly distinctive appearance. Their closest living relatives are the anguid and helodermatid lizards.

Taxonomy

The Varanidae were defined by Estes, de Queiroz and Gauthier as the clade containing the most recent common ancestor of Lanthanotus and Varanus and all of its descendants. A similar definition was formulated by Conrad et al., who defined the Varanidae as the clade containing Varanus varius, Lanthanotus borneensis, and all descendants of their last common ancestor. Using one of these definitions leads to the inclusion of the earless monitor lizard in the family Varanidae.
Lee created a different definition of the Varanidae, defining them as the clade containing Varanus and all taxa more closely related to Varanus than to Lanthanotus; this definition explicitly excludes the earless monitor lizard from the Varanidae. Whether L. borneensis is included in or excluded from the Varanidae depends on the author; for example, Vidal et al. classify the earless monitor lizard as a member of a separate family Lanthanotidae, while Gauthier et al. classify it as a member of Varanidae.

Genera

Genera usually included in Varanidae ):
Genera sometimes included in the Varanidae, treated as under the separate family Lanthanotidae by other authors:
Basal varanoids:
Formerly included in the Varanidae:
Below is a cladogram from Conrad et al. that shows relationships within Varanoidea:

Biology

Monitor lizards are reputed to be among the most intelligent lizards. Most species forage widely and have large home ranges, and many have high stamina. Although most species are carnivorous, three arboreal species in the Philippines are primarily frugivores. Among species of living varanids, the limbs show positive allometry, being larger in larger-bodied species, although the feet become smaller as compared with the lengths of the other limb segments.
Varanids possess unidirectional pulmonary airflow, including airsacs akin to those of birds.