. Bulletin of the British Museum (Natural History). 264 D. S. BROWN. Fig. 5 CryptocUdus euryments (Phillips), Tooth showing ornamental ridges: a and c, axial; b, lingual; d, buccal aspect. length of the symphysis is 32 cm and the length of the left ramus is 224 cm; the symphysis is therefore comparatively much shorter than in pliosaurs (cf measurements given by Andrews, 1913). The internal surface of the dentary is grooved deeply for the reception of the surangular and possibly a splenial. Thin broken fragments perhaps of this latter element remain in place anteriorly on both rami. The
. Bulletin of the British Museum (Natural History). 264 D. S. BROWN. Fig. 5 CryptocUdus euryments (Phillips), Tooth showing ornamental ridges: a and c, axial; b, lingual; d, buccal aspect. length of the symphysis is 32 cm and the length of the left ramus is 224 cm; the symphysis is therefore comparatively much shorter than in pliosaurs (cf measurements given by Andrews, 1913). The internal surface of the dentary is grooved deeply for the reception of the surangular and possibly a splenial. Thin broken fragments perhaps of this latter element remain in place anteriorly on both rami. The posterior elements of the right lower jaw ramus are preserved united in a second piece (Fig. 4), and consist of the fused articular-surangular together with the angular. There is no separate coronoid element in this species. Fusion of the articular and surangular appears to occur in all plesiosaurs. The combined elements form the glenoid for articulation with the skull. This is laterally expanded, and has two concavities to fit the double condyles of the quadrate. In the present specimen the articular-surangular is in the process of fusing with the angular. Anteriorly the suture is clearly visible, but fusion has been completed posteriorly, the line effusion being still traceable from the growth-pattern of the elements. Posteriorly the angular is a thin lamina in plesiosaurs, which is wrapped round the sides and ventral surface of the massive and cylindrical articular. Anteriorly it takes the form of a thin vertical lamina which unites externally with the inner surface of the dentary. Its medial surface is folded to produce a dorsally orientated meckelian groove for the insertion of jaw. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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