On the aquatic squamateDolichosaurus longicollisOwen, 1850 (Cenomanian, Upper Cretaceous), and the evolution of elongate necks in Squamates

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Abstract
The marine squamate, Dolichosaurus longicollis, from the Upper Cretaceous (Cenomanian) Chalk deposits of southeast England is redescribed. The elongate neck of D. longicollis is produced by an increased number of cervical vertebrae. Cervical peduncles are elongate, curved and are not fused to the hypapophyses. There is no scapulocoracoid fenestra, the coracoid is not emarginated, and the scapula and coracoid are not fused. The splenial and angular articulate in a ball-and-socket joint similar to that of mosasaurs and Coniasaurus crassidens. The forelimb and pectoral girdle elements show evidence of reduction as compared to the pelvic girdle and rearlimb. Cladistic analysis of six mosasaur taxa, three ‘aigialosaur’ taxa, Coniasaurus crassidens, Coniasaurus gracilodens, and D. longicollis, using 66 characters, found 27 most parsimonious cladograms (MPCs): 122 steps; C.I. 0.648; H.I. 0.352; R.I. 0.669. A Strict Consensus Tree found support for the monophyly of the Mosasauridae and Aigialosauridae; s...