The Varanidae are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia al ...

s in the superfamily Varanoidea within the Anguimorpha group. The family, a group of

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

and frugivorous lizards, includes the living

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

'' Varanus'' and a number of extinct genera more closely related to ''Varanus'' than to the earless monitor lizard (''Lanthanotus''). ''Varanus'' includes the Komodo dragon (the largest living lizard), 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 earless monitor lizard and chinese crocodile lizard. The oldest members of the family are known from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

of Mongolia.

Taxonomy

The Varanidae were defined (using morphological characteristics) 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) (also using morphological data), who defined the Varanidae as the clade containing ''

Varanus varius The lace monitor or tree goanna (''Varanus varius'') is a member of the monitor lizard family native to eastern Australia. A large lizard, it can reach in total length and in weight. The lace monitor is considered to be a least-concern species ...

'', ''

Lanthanotus borneensis The earless monitor lizard (''Lanthanotus borneensis'') is a semiaquatic, brown lizard native to the Southeast Asian island of Borneo. It is the only living species in the family Lanthanotidae and it is related to the true monitor lizards. Tax ...

'', and all descendants of their last common ancestor. 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''; 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, while Gauthier ''et al.'' (2012) classify it as a member of Varanidae. Taxonomic analysis based on molecular data has identified that ''Varanus'' and ''Lanthanotus'' make up Varanidae, while Shinisaurus is a sister taxon.

Genera

:Genera marked with are extinct Genera included in Varanidae according to Dong ''et al.'', 2022 *'' Ovoo'' Norell, Gao, & Conrad, 2008 (Mongolia, Late Cretaceous) *'' Aiolosaurus'' Gao and Norell, 2000 (Mongolia, Late Cretaceous) *'' Cherminotus'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *'' Saniwides'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *'' Paravaranus'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *'' Proplatynotia'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *'' Telmasaurus'' Gilmore, 1943 (Mongolia, Late Cretaceous) *'' Saniwa'' Leidy, 1870 (Europe, North America,

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

) *'' Archaeovaranus'' Dong ''et al.'', 2022 (China, Eocene) *'' Varanus'' Shaw, 1790

Phylogeny

Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from Dong et al. 2022.

Biology

Monitor lizards are reputed to be among the most intelligent lizards. Most species

forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also us ...

widely and have large home ranges, and many have high stamina. Although most species are carnivorous, three arboreal species in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

('' Varanus olivaceus'', '' Varanus mabitang'', and ''

Varanus bitatawa The Northern Sierra Madre forest monitor (''Varanus bitatawa''), also known by the local names ''bitatawa'', ''baritatawa'', and ''butikaw'', is a large, arboreal, frugivorous lizard of the genus '' Varanus''. The lizard is a distinctive food of ...

'') 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.Unidirectional Airflow In The Lungs Of Birds, Crocs And Now Monitor Lizards
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References

External links