. Bulletin of the British Museum (Natural History). UPPER JURASSIC PLESIOSAUROIDEA 313. Fig. 38 Kiinmerosaiinis lani;hami gen. et sp. nov. , posterior elements of right lower jaw: a. medial; b. dorsal; c, lateral aspect, fr. compressed fragments of skull and two teeth. Other abbreviations as in Fig. 4, p. 263. are very similar to the corresponding parts of Cryptoclidus (cf. Fig. 4). The articular and surangular appear to be fused as in other forms, but what is probably the line of fusion may be traced across the jaw articulation. In lateral view the angular shows marked curvature in the
. Bulletin of the British Museum (Natural History). UPPER JURASSIC PLESIOSAUROIDEA 313. Fig. 38 Kiinmerosaiinis lani;hami gen. et sp. nov. , posterior elements of right lower jaw: a. medial; b. dorsal; c, lateral aspect, fr. compressed fragments of skull and two teeth. Other abbreviations as in Fig. 4, p. 263. are very similar to the corresponding parts of Cryptoclidus (cf. Fig. 4). The articular and surangular appear to be fused as in other forms, but what is probably the line of fusion may be traced across the jaw articulation. In lateral view the angular shows marked curvature in the vertical plane, with the ventral edge concave. This curvature has the effect of lowering the jaw articulation with respect to the toothrow, which also occurs to a slightly lesser in Cryptoclidus but not at all in Tricleidus (cf. Figs 29, 1 and 22). The lateral surfaces of the angular and surangular were overlapped by the dentary, whose posterior limit is indicated on these elements by ridges which are partly overlain by compressed unidentifiable debris and two teeth. The extent of this overlap is shown in Fig. 29. The teeth (Figs 28, 39) are unique amongst plesiosaurs in three respects: they are com- pletely lacking in longitudinal ornamental ridges; they are greatly recurved, the crowns curving through an arc of up to 75°; and in section the distal parts of the crowns are not circular but elliptical, being buccolingually compressed. They are very sharply pointed, and it is notable that even the largest teeth show no signs of attrition. Some large specimens show facets resulting from resorbtion of the root in advance of an approaching replacement tooth. With regard to the proportional length of the snout and the dentition, the present specimen is quite unlike any plesiosaur reconstructed previously. Several characters (including increase in numbers of teeth, reduction in dental ornament, form of the occipital condyle, reduction in length of the paroccipital process and
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