Varanidae

Varanids Temporal range: Late Cretaceous - Holocene, 80–0 Ma PreЄ Є O S D C P T J K Pg N
Komodo dragon (Varanus komodoensis)
Savannah monitor (Varanus exanthematicus)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Superfamily:	Varanoidea
Family:	Varanidae Merrem, 1820
Genera
See text

Varanidae is a family of lizards of the superfamily Varanoidea. The family, a group of carnivorous and frugivorous lizards, includes the extinct Megalania (the largest known lizard), the Komodo dragon (the largest living lizard), and the crocodile monitor. The Varanidae contain the living genus Varanus and a number of extinct taxa. Their closest living relatives are the anguid and helodermatid lizards.

Taxonomy

Varanidae was 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. A similar definition was formulated by Conrad et al. (2008), who defined 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 (Lanthanotus borneensis) in the family Varanidae.

Lee (1997) created a different definition of Varanidae, defining it 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 Varanidae. Whether Lanthanotus borneensis is included in or excluded from Varanidae depends on the author: for example, Vidal et al. (2012) classify the earless monitor lizard as a member of a separate family Lanthanotidae, while Gauthier et al. (2012) classify it as a member of Varanidae.

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).
• †Ovoo Norell, Gao, & Conrad, 2008
• †Saniwa Leidy, 1870
• Varanus Shaw, 1790

Genera sometimes included in 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
• †Cherminotus Borsuk-Bialynicka, 1984
• Lanthanotus Steindachner, 1878

Basal varanoids:

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

Formerly included in Varanidae:

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

Phylogeny

Below is a cladogram from Conrad et al. (2008) that shows relationships within Varanoidea:

Varanoidea	†Mosasaurs †"Saniwa" feisti †Necrosaurus †Saniwides †Telmasaurus  Varanidae   Lanthanotinae  †Aiolosaurus Lanthanotus †Cherminotus  Varaninae  †Ovoo †Saniwa Varanus

Biology

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, and many have high stamina. Although most species are carnivorous, three arboreal species in the Philippines (Varanus olivaceus, Varanus mabitang, and Varanus bitatawa) 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.

See also

• Aigialosauridae
• Helodermatidae
• Mosasauridae
• Necrosauridae

External links

• Varanidae