''Aiolosaurus'' is an extinct

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 nom ...

of monitor 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 epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

. The type and only species, ''Aiolosaurus oriens'', was named in 2000 from Ukhaa Tolgod, a rich fossil site in the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

-age

Djadochta Formation The Djadochta Formation (sometimes Transcription (linguistics), transcribed and also known as Djadokhta, Djadokata, or Dzhadokhtskaya) is a highly fossiliferous geological formation situated in Central Asia, Gobi Desert, dating from the Late Creta ...

Description and history

''Aiolosaurus'' was named in 2000 on the basis of a single

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

specimen cataloged as

IGM Immunoglobulin M (IgM) is one of several isotypes of antibody (also known as immunoglobulin) that are produced by vertebrates. IgM is the largest antibody, and it is the first antibody to appear in the response to initial exposure to an antig ...

3/171. This specimen includes a partial skull and parts of the postcranial skeleton. ''Aiolosaurus'' is named after

Aeolus In Greek mythology, Aeolus or Aiolos (; grc, Αἴολος , ) is a name shared by three mythical characters. These three personages are often difficult to tell apart, and even the ancient mythographers appear to have been perplexed about which A ...

, the

Greek god The following is a list of gods, goddesses, and many other divine and semi-divine figures from ancient Greek mythology and ancient Greek religion. Immortals The Greeks created images of their deities for many purposes. A temple would house the ...

of wind, while the specific name of ''A. oriens'' means "east." Diagnostic features of ''Aiolosaurus'' are found mainly in the skull. They include: *The division of the

nasals In phonetics, a nasal, also called a nasal occlusive or nasal stop in contrast with an oral stop or nasalized consonant, is an occlusive consonant produced with a lowered velum, allowing air to escape freely through the nose. The vast majorit ...

into two bones (they form one bone in living monitors). *A small hole in the snout between the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

and

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

bones called the premaxillary fenestra. *The separation of the premaxilla and septomaxilla bones by a projection of the maxilla bone. *The small size of another hole in the snout called the septomaxillary foramen. *Near the jaw joint, a hole in the

surangular The suprangular or surangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge, it is connected to all other jaw bones: dentary, angular, splenial and articular. It is often a mu ...

bone of the lower jaw that is positioned underneath the coronoid process of the upper jaw.

Classification

''Aiolosaurus'' was initially classified as a basal member of

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 ...

, the superfamily that includes monitor lizards,

helodermatid ''Heloderma'' is a genus of toxicoferan lizards that contains five species, all of which are venomous. It is the only extant genus of the family Helodermatidae. Description The genus ''Heloderma'' contains the Gila monster (''H. suspectum'') ...

s, and

mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on ...

s. ''

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 i ...

'', another Late Cretaceous varanoid from Mongolia, was also classified in this way. In a 2008 phylogenetic analysis, ''Aiolosaurus'' was classified as a member of

Varanidae The Varanidae are a family of lizards in the superfamily Varanoidea within the Anguimorpha group. The family, a group of carnivorous and frugivorous lizards, includes the living genus '' Varanus'' and a number of extinct genera more closely rel ...

. It was placed in the subfamily Lanthanotinae along with ''Cherminotus'' and the living

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 ...

. Another 2008 analysis supported the placement of ''Aiolosaurus'' in Varanidae but did not find it to be a member of Lanthanotinae. Instead, it was found to be a more basal varanid. As some of the earliest monitor lizards, ''Aiolosaurus'', ''Cherminotus'', and the related ''

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 p ...

'' are representative of the first

evolutionary radiation An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. Radiations may affect one clade or many, and be rapid ...

of varanids.

References

{{Taxonbar, from=Q4697559 Late Cretaceous lepidosaurs of Asia Cretaceous lizards Monitor lizards Prehistoric reptile genera Fossil taxa described in 2000