Wikipedia
Coniasaurus is an extinct genus of Late Cretaceous marine squamates that range in age from Cenomanian to Santonian. It was first described by Richard Owens in 1850 from lower Cenomanian chalk deposits in southeast England. Two species have been described from this genus: C.crassidens (Owen, 1850), known from Cenomanian to Santonian deposits from southeast England, Germany and North America, and C.gracilodens (Caldwell, 1999) from the Cenomanian of southeast England.
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 and other dolichosaurs, it may have had four short limbs and an elongate neck and body. A maximum length of about 0.5 m has been proposed.
Phylogenetic analysis suggests that Coniasaurus is a sister group to the Mosasauroidea within the Pythonomorpha clade.