. Bulletin. Natural history; Natuurlijke historie. Fig. 38. Reconstructed 'nothosaur' skeletons in dorsal aspect. A, "Pachypleurosaurus" (= Neustico- saurus) modified from Carroll and Gaskill (1985) and Peyer (1944); B, Lanosaurus after Peyer (1933). Compare with Fig. 21. Scale bar = cm. (Most specimens of Neuslicosaurus smaller.) primitive diapsid Petrolacosaurus (following Rieppel 1989), the Younginiformes, and Claudiosaurus as primitive outgroups for comparison with the traditional Sauropterygia during rigorous character analysis. It is a happy circumstance that Claudiosaurus
. Bulletin. Natural history; Natuurlijke historie. Fig. 38. Reconstructed 'nothosaur' skeletons in dorsal aspect. A, "Pachypleurosaurus" (= Neustico- saurus) modified from Carroll and Gaskill (1985) and Peyer (1944); B, Lanosaurus after Peyer (1933). Compare with Fig. 21. Scale bar = cm. (Most specimens of Neuslicosaurus smaller.) primitive diapsid Petrolacosaurus (following Rieppel 1989), the Younginiformes, and Claudiosaurus as primitive outgroups for comparison with the traditional Sauropterygia during rigorous character analysis. It is a happy circumstance that Claudiosaurus and the Younginiformes, as potential structural "ancestors" and sister-groups to the unknown ancestors of the mainstream Sauropterygia, are Permian in age, whereas no undisputed 'nothosaur' or plesiosaur is known from before the Triassic (although by definition the lineage must have been present). Most 'nothosaurs' are Middle Triassic in age and the group does not appear to enter the Jurassic. Plesiosaurs are primarily Jurassic and Cretaceous animals. Each of the major groups of the Sauropterygia have likewise been examined for presumably derived characteristics and these are listed in Table 2. Appendix C details discussions of each character and its significance. Figure 40 provides a hypothetical cladogram of sauropterygian relationships which was constructed from these characters and which places each derived suite in perspective. The 84 characters of the data matrix were analyzed with the branch and bound algorithm of PAUP (Phylogenetic Analysis Using Parsimony) for the Macintosh (Swofford 1989). Six equally parsimonious trees of 150 steps were produced at. 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 Peabody Museum of Natural History. New Haven : The Museum
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