''Coniasaurus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

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 ...

marine squamates that range in age from

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

. It was first described by

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomy, comparative anatomist and paleontology, palaeontologist. Owen is generally considered to have been an outstanding naturalist with a remarkabl ...

in 1850 from lower Cenomanian

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...

deposits in

South East England South East England is one of the nine official regions of England, regions of England that are in the ITL 1 statistical regions of England, top level category for Statistics, statistical purposes. It consists of the nine counties of england, ...

(

Sussex Sussex (Help:IPA/English, /ˈsʌsɪks/; from the Old English ''Sūþseaxe''; lit. 'South Saxons'; 'Sussex') is an area within South East England that was historically a kingdom of Sussex, kingdom and, later, a Historic counties of England, ...

). Two species have been described from this genus: ''C. crassidens'' (Owen, 1850), known from Cenomanian to Santonian deposits from South East England,

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, and ''C. gracilodens'' (Caldwell, 1999) from the Cenomanian of southeast

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. ''Coniasaurus'' has only been described from incomplete specimens, but it is known to have had a relatively elongate skull with specialised teeth. By comparison with '' Dolichosaurus'', it may have had four short limbs and an elongate neck and body. A maximum length between has been proposed.

Phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

suggests that ''Coniasaurus'' is a

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the

Mosasauroidea Mosasauroidea is a superfamily of extinct marine lizards that existed during the Late Cretaceous. Basal members of this group consist of small semiaquatic forms with terrestrial limbs ("plesiopedal"), while laters members include larger fully ...

within the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Pythonomorpha Mosasauria is a clade of Aquatic animal, aquatic and semiaquatic squamates that lived during the Cretaceous period. Fossils belonging to the group have been found in all continents around the world. Early mosasaurians like Dolichosauridae, dolich ...

References

{{Taxonbar, from=Q3686975 Fossil taxa described in 1850 Prehistoric squamates Prehistoric reptile genera Cretaceous lizards Late Cretaceous lepidosaurs of Europe Dolichosauridae