738


Journal of Paleontology 92(4):734–742


of AUP 11192, as preserved, are 10.5mm and 5.4mm, respectively.


Phylogenetic analyses


The parsimony analysis found 7176 MPTs of 265 steps, and the 50% majority rule consensus tree shows good resolution for most clades (Fig. 3.1). The consistency (CI) and retention indices (RI) for the 50% majority rule consensus tree are 0.38628 and 0.66403, respectively. No clade had a Bremer support score>1 (complete statistics and associated files for both phylogenetic analyses can be found in the Supplemental Data). Generally, our results agree with those of other recent studies (Rauhut et al., 2012; Martínez et al., 2013; Apesteguía et al., 2014; Cau et al., 2014; Hsiou et al., 2015). One of the major differences is that our analysis recovered Pleurosauridae as the sister group of Sphenodontidae. The terrestrial Pami- zinsaurus Reynoso, 1997 is the earliest diverging taxon within the Sphenodontidae, which includes two major clades. The first clade includes Ankylosphenodon Reynoso, 2000, Derasmo- saurus Barbera and Macuglia, 1988, Oenosaurus Rauhut et al., 2012, and Zapatadon Reynoso and Clark, 1998 in a polytomy, whereas the second clade is well resolved, recovering the Early Jurassic Cynosphenodon Reynoso, 1996 and the modern Sphe- nodon Gray, 1831 as successive sister taxa to the clade com- prising Theretairus Simpson, 1926 and Sphenovipera Reynoso, 2005. The strict consensus tree of the second analysis of Cau et al. (2014) also found Derasmosaurus, Oenosaurus, and Zapatadon in a similar polytomy, and forming the sister group of the clade comprising Sphenodon, Cynosphenodon, Spheno- vipera, Kawasphenodon Apesteguía, 2005, and Theretairus. The close relationship of Sphenovipera and Theretairus has been constantly recovered in previous analyses (e.g., Martínez et al., 2013; Apesteguía et al., 2014; Hsiou et al., 2015). Within clevosaurs, Brachyrhinodon Huene, 1910 was


Figure 2. Fraserosphenodon latidens n. comb.: (1, 2) AUP 11191, right premaxilla, shown in labial (1) and lingual (2) views; (3–5) AUP 11192, right dentary, shown in labial (3), lingual (4), and occlusal (5) views. Scale bars=6mm (1, 2); 3.5mm (3–5).


The specimen includes three generations of teeth, but canini- form teeth are lacking. The front ofAUP11192 has two rounded successional teeth similar to those of the premaxilla. These teeth are followed by a series of six or seven small semicircular remnants of hatchling teeth with minor signs of wear on the occlusal surfaces. On the distal end of this element, we found three or four additional teeth that in both labial and lingual view show the same triangular shape seen inVMNH 525. In occlusal view, the teeth of AUP 11192 show heavy signs of wear and the round, bulbous shape seen in VMNH 525. This round, bulbous shape is more pronounced in the distalmost additional tooth of AUP 11192. Additionally, AUP 11192 includes three mental foramina of relatively large size (Fig. 2.3), which suggests that this specimen comes from a juvenile. The length and height


recovered as the earliest diverging taxon. All Clevosaurus spe- cies are grouped in a polytomy, which obscures the relationships between the species. The results for clevosaurs are quite similar to those recovered by the strict consensus tree of Hsiou et al. (2015). The only difference is that in their analysis, Poly- sphenodon Jaekel, 1911 appears as the earliest diverging taxon within Clevosauridae, but all other taxa were recovered in a polytomy. A similar polytomy for clevosaurs was also shown in the strict consensus tree of Rauhut et al. (2012). Our results agree with the work of Martínez et al. (2013) and Hsiou et al. (2015) in recovering Fraserosphenodon latidens as an early diverging opisthodontian. Indeed, we recovered F. latidens as the earliest diverging taxon within Opisthodontia. This clearly confirms that F. latidens is not referable to the genus Clevo- saurus, and supports the erection of a new opisthodontian genus, as previously suggested (Jones, 2006a, 2009; Martínez et al., 2013; Hsiou et al., 2015; Klein et al., 2015). Within Opisthodontia, the relationships of eilenodontines are quite well resolved; our results only differ from the works of Martínez et al. (2013) and Cau et al. (2014) in finding Ankylosphenodon outside of Opisthodontia. Another major difference compared to the previous ana-


lyses of Martínez et al. (2013) and Hsiou et al. (2015) is that the Triassic taxon Pelecymala was no longer recovered as closely


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