''Karaurus'' (meaning ''head-tail'') is an extinct genus of

stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten ...

(

Caudata The Caudata are a group of amphibians containing the extant salamanders (Urodela) and all extinct species of amphibians more closely related to salamanders than to frogs. They are typically characterized by a superficially lizard-like appearance ...

) from the Middle to Late Jurassic (

Callovian In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the ...

–

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

)

Karabastau Formation The Karabastau Formation ( kk, Qarabastaý svıtasy) is a geological formation and lagerstätte in the Karatau Mountains of southern Kazakhstan whose strata date to the Middle to Late Jurassic. It is an important locality for insect fossils that ...

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...

. It is one of the oldest salamanders known. ''Karaurus'' was large for a Jurassic salamander, about long, and very similar anatomically to modern salamanders. ''Karaurus'' is thought to have fed using

suction feeding Aquatic feeding mechanisms face a special difficulty as compared to feeding on land, because the density of water is about the same as that of the prey, so the prey tends to be pushed away when the mouth is closed. This problem was first identifi ...

via the enlargement of the

buccal cavity The buccal space (also termed the buccinator space) is a fascial spaces of the head and neck, fascial space of the head and neck (sometimes also termed fascial tissue spaces or tissue spaces). It is a potential space in the cheek, and is paired on ...

on small fish and invertebrates, with the well developed palatal dentition (teeth on the roof of the mouth) and marginal teeth helping to grasp prey. ''Karaurus'' is thought to form a clade with ''

Kokartus ''Kokartus'' is an extinct genus of prehistoric stem-group salamander (Caudata) from the Middle Jurassic Balabansai Formation of Kyrgyzstan. The absence of clear lines of arrested growth and annuli in long bones suggests that the animals lived i ...

'' from the Middle Jurassic (

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Strat ...

) of Kyrgyzstan, and ''

Marmorerpeton ''Marmorerpeton'' is an extinct genus of prehistoric stem group-salamanders that lived in Britain during the Bathonian stage of the Middle Jurassic. They are among the oldest known salamanders. Two species were named when the genus was first d ...

'' from the Bathonian of Britain, together forming the

Karauridae The Karauridae are a family of stem-group salamanders (Caudata) that are known from the Middle Jurassic to Late Jurassic in Central Asia (Kazakhstan and Kyrgyzstan) and Western Europe (United Kingdom). The family includes three members: ''Karauru ...

, which are closely related to crown salamanders. Like other members of Karauridae, ''Karaurus'' is

neotenic Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared ...

References

Prehistoric salamanders Late Jurassic amphibians Prehistoric amphibians of Asia Prehistoric amphibian genera Fossil taxa described in 1978 {{paleo-salamander-stub