. Bulletin of the British Museum (Natural History). UPPER JURASSIC PLESIOSAUROIDEA 333 istically separated posteriorly by a wide intercoracoid foramen in Cretaceous long-necked forms. 28. Anterior border of pubis. Welles (1943 : 199) stated that the 'pubes ... may become convex anteriorly or concave'. This, however, appears to be an ontogenetic character. 'Juveniles' have rounded pubes which are therefore convex anteriorly; but as ossification reaches the region of the posterior gastralia, concavities in the anterior border appear which mark the places of contact and possible interlock with th
. Bulletin of the British Museum (Natural History). UPPER JURASSIC PLESIOSAUROIDEA 333 istically separated posteriorly by a wide intercoracoid foramen in Cretaceous long-necked forms. 28. Anterior border of pubis. Welles (1943 : 199) stated that the 'pubes ... may become convex anteriorly or concave'. This, however, appears to be an ontogenetic character. 'Juveniles' have rounded pubes which are therefore convex anteriorly; but as ossification reaches the region of the posterior gastralia, concavities in the anterior border appear which mark the places of contact and possible interlock with the plastron (present work). 29. Relative length of ischia. The ischia are relatively short anteroposteriorly in long- necked forms and relatively long in short-necked large-skulled forms (correlation first noticed by Mehl, 1912). 30. Pelvic bar. Welles (1962) divided his family Elasmosauridae into two subfamilies upon the presence or absence of a pectoral bar and a median pelvic bar. However, as with the pectoral bar, anterior growth of tne ischia and posterior growth of the pubes towards each other in the midline is an ontogen' tic feature. Complete ossification of the pelvic bar (as in Elasmosaurus platyurus and Brai i:asaurus brancai) is probably not of major taxonomic significance. 31. Ilial breadth. Welles (1943:199) listed 'ilia becoming narrow proximally or. 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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