with a negative silhouette value), and a group with the rest of the pterosaurs; whereas the four-group model made a new group that contained Rhamphorhynchus, Dimorphodon, Eudimorphodon, and Scleromochlus, all with negative silhouette values. N. “Basal” Avemetatarsalia The Spearman and Pearson BDC plots for the “basal” avemetatarsalian subset analyses were almost identical, each containing three blocks of positive correlation: 1) Silesauridae + Lagosuchus, 2) Aphanosauria, and 3) Lagerpetidae (Figure 47). The likely lagerpetid Scleromochlus does not correlate positively or negatively with any other taxon in the analysis. The MDS results (Figure 48) agree with the BDC plots in showing three clusters of taxa. Both Scleromochlus and Dromomeron are far removed from the other lagerpetids. The PAM results (Figure 49) had the highest average silhouette values at three groups (0.43) or four groups (0.4). The three-group model recognized Silesauridae + Lagosuchus, Lagerpetidae + Dromomeron, and Aphanosauria + Scleromochlus; whereas the fourgroup model separated out Dromomeron into its own group. The FANNY results (Figure 50) had essentially the same average silhouette values and taxic composition of groups at three groups (0.43) and four groups (0.4), but it had its largest average silhouette value of 0.46 at two groups. This two-group model places the silesaurids, aphanosaurs, and Lagosuchus in one group and the lagerpetids, Dromomeron, and Scleromochlus in the other group. DISCUSSION A. “Protorosauria” There is strong evidence for continuity within and between Tanystropheidae and Dinocephalosauridae, and those groups are, in turn, surrounded by discontinuity as indicated in BDC, MDS, PAM, and FANNY. We do not find convincing evidence for continuity between Protorosaurus and these animals. As such, we suggest that Tanystropheidae + Dinocephalosauridae is a holobaramin, and “Protorosauria” is either apobaraminic or polybaraminic. Interestingly, Jesairosaurus showed positive correlation with the dinocephalosaurids in BDC and was united with them in the four-group PAM analysis. This matches a recent phylogenetic analysis that recovered it as the sister taxon to Dinocephalosaurus (De Oliveira et al. 2020). Unfortunately, our analyses did not contain any sharovipterygids, which are recognized as close relatives in phylogenetic studies of “protorosaurs” (Spiekman et al. 2021). Future analyses focusing on “protorosaurs” as well as creatures that may or may not be archosauromorphs like drepanosauromorphs and weigeltisaurids would be of great help to understanding the baraminic relationships of these enigmatic creatures. B. Allokotosauria The BDC, MDS, PAM, and FANNY results all show strong evidence for discontinuity surrounding Allokotosauria, making it an apobaramin. However, the internal continuity of Allokotosauria is not so clear. The Spearman BDC shows evidence for continuity among the allokotosaurs, but the Pearson BDC splits the group up into its two families: Trilophosauridae and Azendohsauridae. The MDS results show little evidence of discontinuity between the two. FANNY is slightly better when viewing them as separate groups, but PAM has higher silhouette width values when they are united. Some of these issues may reflect the choice of outgroup, since some of the outgroup Figure 23. Baraminic distance correlation (BDC) results for the Phytosauria subset dataset using: A) Pearson correlation coefficient and B) Spearman correlation coefficient. Black squares indicate significant positive correlation, whereas open circles indicate significant negative correlation. taxa are drastically different from one another (e.g., Vancleavea vs. Sarmatosuchus). Given these results, we tentatively conclude that Allokotosauria may be a holobaramin made of two monobaramins: Azendohsauridae and Trilophosauridae. Future analyses more focused on this group and including more taxa may recognize each as its own holobaramin, however. C. Rhynchosauria With the inclusion of taxa with low taxic relevance scores, such as Noteosuchus, Eohyosaurus, and Langeronyx, the BDC and MDS results can be difficult to understand. When those three species are removed, three main groupings of continuity and discontinuity can be seen within the order Rhynchosauria. There is a possibility that, even though there is little known about these species, they provide a link between the rhynchosaurids and “basal” forms. However, we think the best interpretation is that the “basal” rhynchosaurs may be in a separate holobaramin than the rhynchosaurids, sometimes clustering and correlating more closely with the outgroup than the other rhynchosaurs. The subgroups Hyperodapedontinae and the non-hyperodapedontine rhynchosaurids may both be monobaramins within the holobaramin of Rhynchosauridae. Alternatively, it may be that Rhynchosauridae is an apobaramin made up of two holobaramins. MCLAIN, CLAUSEN, PEREZ, BEEBE, AND AHTEN Archosauromorph Baraminology 2023 ICC 509
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