''Dolichosaurus'' (meaning "long lizard") is an

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 ...

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 ...

of marine

squamate Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, ...

of the Upper Cretaceous

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

chalk deposits of England. Sister-group relationships between coniasaurs, dolichosaurs,

Aigialosauridae Aigialosauridae (from Greek, ''aigialos'' = "seashore" and ''sauros''= lizard) is a family of Late Cretaceous semiaquatic pythonomorph lizards closely related to the mosasaurs. Regarded by some paleontologists as a distinct monophyletic group an ...

and Mosasauridae are an unresolved

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...

. The paleobiology of ''Dolichosaurus'' is reconstructed as similar to coniasaurs,

nothosaurs Nothosaurs (order Nothosauroidea) were Triassic marine sauropterygian reptiles that may have lived like seals of today, catching food in water but coming ashore on rocks and beaches. They averaged about in length, with a long body and tail.F. v. ...

, and modern

sea snakes Sea snakes, or coral reef snakes, are elapid snakes that inhabit marine environments for most or all of their lives. They belong to two subfamilies, Hydrophiinae and Laticaudinae. Hydrophiinae also includes Australasian terrestrial snakes, where ...

.Michael W. Caldwell
On the aquatic squamate ''Dolichosaurus longicollis'' Owen, 1850 (Cenomanian, Upper Cretaceous), and the evolution of elongate necks in squamates
''Journal of Vertebrate Paleontology'' 20(4):720-735. 2000. doi: https://dx.doi.org/10.1671/0272-4634(2000)020 720:OTASDL.0.CO;2

References

Cretaceous lizards Late Cretaceous lepidosaurs of Europe Fossil taxa described in 1850 Taxa named by Richard Owen Prehistoric squamates Prehistoric reptile genera {{paleo-lizard-stub