The Varanidae are a

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

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 alt ...

s in the

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Varanoidea Varanoidea is a superfamily of lizards, including the well-known family Varanidae (the monitors and goannas). Also included in the Varanoidea are the Lanthanotidae (earless monitor lizards), and the extinct Palaeovaranidae. Throughout their lon ...

within the

Anguimorpha The Anguimorpha is a suborder of squamates. The group was named by Fürbringer in 1900 to include all autarchoglossans closer to '' Varanus'' and '' Anguis'' than ''Scincus ''Scincus'' is a genus of skinks, lizards in the family Scincidae. Th ...

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 sof ...

and

frugivorous A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance and ...

lizards, includes the living

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

'' Varanus'' and a number of extinct genera more closely related to ''Varanus'' than to the

earless monitor lizard 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. Taxo ...

(''Lanthanotus''). ''Varanus'' includes the

Komodo dragon The Komodo dragon (''Varanus komodoensis''), also known as the Komodo monitor, is a member of the monitor lizard family Varanidae that is endemic to the Indonesian islands of Komodo, Rinca, Flores, and Gili Motang. It is the largest extant ...

(the largest living lizard),

crocodile monitor ''Varanus salvadorii'', also known as the crocodile monitor, Papuan monitor and Salvadori's monitor, is a species of monitor lizard endemic to New Guinea. It is the largest monitor lizard known from New Guinea, and is one of the longest lizard ...

savannah monitor The savannah monitor (''Varanus exanthematicus'') is a medium-sized species of monitor lizard native to Africa. The species is known as Bosc's monitor in Europe, since French scientist Louis Bosc first described the species. It belongs to the su ...

, the

goanna A goanna is any one of several species of lizards of the genus '' Varanus'' found in Australia and Southeast Asia. Around 70 species of ''Varanus'' are known, 25 of which are found in Australia. This varied group of carnivorous reptiles ranges ...

s of Australia and Southeast Asia, and various other species with a similarly distinctive appearance. Their closest living relatives are the

and

chinese crocodile lizard The Chinese crocodile lizard (''Shinisaurus crocodilurus'') is a semiaquatic anguimorph lizard found only in cool forests in southeast China and northeast Vietnam. The Chinese crocodile lizard spends much of its time in shallow water or in overha ...

. 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'', the ...

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 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. Taxo ...

'' 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'', 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

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 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. Taxo ...

, 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 Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

Genera 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 nomenclat ...

included in Varanidae according to Dong ''et al.'', 2022 *''

Ovoo Ovoo, oboo, or obo ( mn, овоо, bua, обоо, kjh, обаа, Traditional Mongol: , "heap"; Chinese: 敖包 ''áobāo'', lit. "magnificent bundle .e. shrine) are sacred stone heaps used as altars or shrines in Mongolian folk religious pra ...

'' Norell, Gao, & Conrad, 2008 (Mongolia, Late Cretaceous) *''

Aiolosaurus ''Aiolosaurus'' is an extinct genus of monitor lizard from the Late Cretaceous of Mongolia. The type and only species, ''Aiolosaurus oriens'', was named in 2000 from Ukhaa Tolgod, a rich fossil site in the Campanian-age Djadochta Formati ...

'' Gao and Norell, 2000 (Mongolia, Late Cretaceous) *''

Cherminotus ''Cherminotus'' is an extinct genus of monitor lizard from the Late Cretaceous of Mongolia. The type and only species, ''Cherminotus longifrons'', was named in 1984. Description and history ''Cherminotus longifrons'' was first described ...

'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *'' Saniwides'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *'' Paravaranus'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *''

Proplatynotia ''Proplatynotia'' is an extinct genus of varanoid lizard from the Late Cretaceous of Mongolia. Fossils have been found in the Barun Goyot Formation, which is mid-Campanian in age. The type and only species, ''P. longirostratia'', was named in ...

'' Borsuk-Bialynicka, 1984 (Mongolia, Late Cretaceous) *''

Telmasaurus ''Telmasaurus'' is an extinct genus of varanoid lizard 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 e ...

'' Gilmore, 1943 (Mongolia, Late Cretaceous) *''

Saniwa ''Saniwa'' is an extinct genus of varanid lizard that lived about 48 million years ago during the Eocene epoch. It is known from well-preserved fossils found in the Bridger and Green River Formations of Wyoming. The type species ''S. ensidens'' ...

'' Leidy, 1870 (Europe, North America,

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

) *''

Archaeovaranus ''Archaeovaranus'' (meaning "ancient '' Varanus''") is genus of varanid lizard from the early Eocene (Ypresian) Yuhuangding Formation of Hubei Province, China. The genus contains a single species, ''Archaeovaranus lii'', known from a nearly comp ...

'' 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 d ...

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 used m ...

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

arboreal Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...

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 The Gray's monitor (''Varanus olivaceus'') is a large (180 cm, >9 kg) monitor lizard known only from lowland dipterocarp forest in southern Luzon, Catanduanes, and Polillo Island, all islands in the Philippines. It is also known as Gr ...

'', ''

Varanus mabitang The Panay monitor (''Varanus mabitang'') is an endangered monitor lizard native to Panay Island in the Philippines. Unlike most monitors, it is a specialized frugivore. Distribution and habitat The Panay monitor occurs only on Panay, inhabitin ...

'', and '' Varanus bitatawa'') are primarily frugivores. Among species of living varanids, the limbs show positive

allometry Allometry is the study of the relationship of body size to shape, anatomy, physiology and finally behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Julian Huxley in 1932. Overview Allom ...

, 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
/ref>

References

External links