. Bulletin. Natural history. Text-fig. 91. A. Lateral view of left quadrate. B. Posterior view of left quadrate. Prognalhodon rapax (reconstructed after the quadrates of NJGS 9827, X %). another. P. rapax may be close to P. giganteus but both species are much too incom- pletely known to hazard speculation on interrelationships. Genus PLESIOTYLOSAURUS Camp 1942 Plesiotylosaurus Camp, 1942, p. 18. Generic Type. Plesiotylosaurus crassidens Camp 1942. Diagnosis. Premaxilla with no rostrum anterior to premaxillary teeth. Thirteen teeth in maxilla. Prefrontal forms large portion of posterolateral bo
. Bulletin. Natural history. Text-fig. 91. A. Lateral view of left quadrate. B. Posterior view of left quadrate. Prognalhodon rapax (reconstructed after the quadrates of NJGS 9827, X %). another. P. rapax may be close to P. giganteus but both species are much too incom- pletely known to hazard speculation on interrelationships. Genus PLESIOTYLOSAURUS Camp 1942 Plesiotylosaurus Camp, 1942, p. 18. Generic Type. Plesiotylosaurus crassidens Camp 1942. Diagnosis. Premaxilla with no rostrum anterior to premaxillary teeth. Thirteen teeth in maxilla. Prefrontal forms large portion of posterolateral border of external nares; supraorbital wing with triangular ala, contacts postorbitofrontal dorsally over orbit lateral to external edge of frontal. Frontal not emarginate above orbits, median dorsal ridge (?)absent. Parietal foramen small, closely embraced on either side by short tongues from frontal. Margins of dorsal parietal field diverge posteriorly. Dorsal surface of postorbito- frontal very well exposed. Squamosal wing to parietal large. At least seven pterygoid teeth. Suprastapedial process distally fused to infrastapedial process on quadrate. Tympanic ala thick, quadrate massive. Sixteen to seventeen teeth in dentary. Small projection of dentary anterior to first dentary tooth. Mandibular teeth large and heavy. Superior border of scapula strongly convex, posterior border very strongly emargi- nated. Distal and proximal ends of humerus moderately expanded. Discussion. The foregoing diagnosis was taken from descriptions and illustrations in Camp (1942). Although the reviewer has not examined the California material, it is his opinion that Plesiotylosaurus belongs in the Plioplatecarpinae close to Prognathodon because of its bluntly terminated premaxilla and the large maxillary and pterygoid teeth. It is distinguishable from Prognathodon in its long and slender snout, the greater number of mandibular teeth and in its peculiar quadrate. The head of the humerus is squarely te
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