Coniasaurus

{{Short description|Extinct genus of lizards}}

{{Italic title}}

{{Automatic taxobox

| name = Coniasaurus

| fossil_range = Late Cretaceous, {{Fossil range|100|84}}

| image = Coniasaurus.jpg

| image_caption = C. crassidens holotype, drawn by James Erxleben in 1850

| taxon = Coniasaurus

| authority = Owen, 1850

| subdivision_ranks = Species

| subdivision =

• †C. crassidens Owen, 1850 (type)
• †C. gracilodens Caldwell, 1999

}}

Coniasaurus is an extinct genus of Late Cretaceous marine squamates that range in age from Cenomanian to Santonian.{{cite journal | url=http://www.psjournals.org/doi/abs/10.1666/0022-3360%282006%2980%5B589%3ACORSFT%5D2.0.CO%3B2?journalCode=pleo | title=Coniasaurus Owen, 1850 (Reptilia: Squamata), from the Upper Cretaceous Niobrara Chalk of western Kansas | author=Shimada K. & Bell G.L.Jr | journal=Journal of Paleontology | year=2006 | volume=80 | issue=3 | pages=589–593 | doi=10.1666/0022-3360(2006)80[589:corsft]2.0.co;2 | url-access=subscription }}{{Dead link|date=July 2020 |bot=InternetArchiveBot |fix-attempted=yes }} It was first described by Richard Owen in 1850 from lower Cenomanian chalk deposits in South East England (Sussex).Owen, R. (1850). Descriptions of the fossils of the Chalk Formation. Description of the fossil reptiles of the Chalk Formation. The Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex 378-404{{cite journal | url=http://ac.els-cdn.com/S0024408298901613/1-s2.0-S0024408298901613-main.pdf?_tid=5271807a-d607-11e4-9e1e-00000aab0f01&acdnat=1427628946_ea4e5126806ff6fc342fe841ec29ab10 | title=Redescription, palaeobiogeography and palaeoecology of Coniasaurus crassidens Owen, 1850 (Squamata) from the Lower Chalk (Cretaceous; Cenomanian) of SE England | author=Caldwell M.W. & Cooper J.A. | journal=Zoological Journal of the Linnean Society | year=1999 | volume=127 | issue=4 | pages=423–452 | doi=10.1111/j.1096-3642.1999.tb01380.x| doi-access=free }} Two species have been described from this genus: C. crassidens (Owen, 1850), known from Cenomanian to Santonian deposits from South East 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, it may have had four short limbs and an elongate neck and body. A maximum length between {{cvt|0.5|-|1|m|ft}} has been proposed.{{cite journal|last1=Bardet|first1=Nathalie|title=The Cenomanian-Turonian (late Cretaceous) radiation of marine squamates (Reptilia): the role of the Mediterranean Tethys|journal=Bulletin de la Société Géologique de France|date=2008|volume=179|issue=6|pages=605–623|doi=10.2113/gssgfbull.179.6.605}}

Phylogenetic analysis suggests that Coniasaurus is a sister group to the Mosasauroidea within the clade Pythonomorpha.{{cite journal | url=http://ac.els-cdn.com/S0024408297901448/1-s2.0-S0024408297901448-main.pdf?_tid=a935ddee-d615-11e4-bd9e-00000aacb35f&acdnat=1427635105_b10a5fc3f1ba8d85b6c276fdd85b2713 | title=Squamate phylogeny and the relationships of snakes and mosasauroids | author=Caldwell M.A. | journal=Zoological Journal of the Linnean Society | year=1999 | volume=125 | issue=1 | pages=115–147 | doi=10.1111/j.1096-3642.1999.tb00587.x| doi-access=free }}