''Aiolosaurus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

monitor lizard Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and West African Nile monitor, one species is also found in south America as an invasive species. A ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

Mongolia Mongolia is a landlocked country in East Asia, bordered by Russia to the north and China to the south and southeast. It covers an area of , with a population of 3.5 million, making it the world's List of countries and dependencies by po ...

. The

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

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. Campa ...

-age Djadochta Formation.

Description and history

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

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen cataloged as

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

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

Aeolus In Greek mythology, Aiolos, transcribed as Aeolus (; ; ) refers to three characters. These three are often difficult to tell apart, and even the ancient mythographers appear to have been perplexed about which Aeolus was which. Diodorus Siculus m ...

, the

Greek god In ancient Greece, deities were regarded as immortal, anthropomorphic, and powerful. They were conceived of as individual persons, rather than abstract concepts or notions, and were described as being similar to humans in appearance, albeit larg ...

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 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 mammals h ...

and

maxilla In vertebrates, the maxilla (: maxillae ) 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. The two maxil ...

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 surangular or suprangular 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 bone, angular, splenial and articular. It is o ...

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 ...

, the superfamily that includes monitor lizards, helodermatids, and

mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains wer ...

s. '' Cherminotus'', 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 and order Anguimorpha. The family, a group of carnivorous and frugivorous lizards, includes the living genus '' Varanus'' and a number of extinct genera more closely related ...

. 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 (, , , , Traditional Mongol: , "heap"; Chinese: 敖包 ''áobāo'', lit. "magnificent bundle .e. shrine) are cairns used as border markers or shrines in Mongolian folk religious practice and in the religion of other Mongol ...

'' 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. A significantly large and diverse radiation within ...

of varanids.

References

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