Varanidae

The Varanidae were defined by Estes, de Queiroz and Gauthier (1988) as the clade containing the most recent common ancestor of Lanthanotus and Varanus and all of its descendants.[3] A similar definition was formulated by Conrad et al. (2008), who defined the Varanidae as the clade containing Varanus varius, Lanthanotus borneensis, and all descendants of their last common ancestor.[4] Using one of these definitions leads to the inclusion of the earless monitor lizard (L. borneensis) in the family Varanidae.

Lee (1997) 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;[5][6] 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. (2012) classify the earless monitor lizard as a member of a separate family Lanthanotidae,[7] while Gauthier et al. (2012) classify it as a member of Varanidae.[8]

Genera

The extinct Saniwa ensidens

Genera marked with † are extinct

Genera usually included in Varanidae (under subfamily Varaninae according to Conrad et al., 2008)):

• †Iberovaranus Hoffstetter, 1969 - Considered to be a junior synonym of Varanus by Delfino et al. (2013).[9]
• †Ovoo Norell, Gao, & Conrad, 2008[10]
• †Saniwa Leidy, 1870
• Varanus Shaw, 1790

Genera sometimes included in the Varanidae (under subfamily Lanthanotinae according to Conrad et al., 2008), treated as under the separate family Lanthanotidae by other authors:

• †Aiolosaurus Gao and Norell, 2000[10]
• †Cherminotus Borsuk-Bialynicka, 1984
• Lanthanotus Steindachner, 1878

Basal varanoids:

• †Saniwides Borsuk-Bialynicka, 1984
• †Telmasaurus Gilmore, 1943[10]
• †Palaeosaniwa Gilmore, 1928 - Might actually be more closely related to helodermatids than to varanids.[4]

Formerly included in the Varanidae:

• †Pachyvaranus Arambourg, 1952 - Moved to a separate group of varanoid squamates, Pachyvaranidae, by Houssaye et al. (2011).[11]

Gray's monitor (Varanus olivaceus) is a tree-dwelling varanid from the Philippines that primarily feeds on fruit

Monitor lizards are reputed to be among the most intelligent lizards. Most species forage widely and have large home ranges,[13] and many have high stamina.[14] Although most species are carnivorous, three arboreal species in the Philippines (Varanus olivaceus, Varanus mabitang, and Varanus bitatawa) are primarily frugivores.[1][15] 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.[16]

Varanids possess unidirectional pulmonary airflow, including airsacs akin to those of birds.[17]

• Aigialosauridae
• Helodermatidae
• Mosasauridae
• Necrosauridae

• Varanidae