Benton, M. J. (2016). The Chinese pareiasaurs. Zoological Journal of the Linnean Society, 177(4), 813-853. https://doi.org/10.1111/zoj.12389

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1 1 2 3 1 [Abstract] 4 5 2 6 3 Pareiasaurs were important medium- to large-sized herbivores in the Middle and Late 7 8 4 Permian, some 268-252 million years (Myr) ago. They are best known from abundant remains 9 10 5 of several taxa each in South Africa and Russia, with isolated finds from other parts of the 11 6 world. Six genera and species of pareiasaurs have been described from China, and yet they 12 13 7 have not been reviewed. Of these six, Tsiyuania may be a synonym of Honania, but this taxon 14 15 8 is not further considered here. The other four, which were named for separate finds from the 16 9 Sunjiagou Formation (Changhsingian, 254-252 Myr) show considerable similarities. Despite 17 18 10 earlier suggestions,For there are no Review convincing anatomical charactersOnly to distinguish Shihtienfenia, 19 20 11 Shansisaurus, and Huanghesaurus, and these three genera are synonymised as Shihtienfenia 21 12 permica Young & Yeh, 1963. The fourth taxon, Sanchuansaurus pygmaeus Gao, 1989, shows 22 23 13 distinctly different teeth from those of Huanghesaurus (= Shihtienfenia), and was about one- 24 25 14 third of the size, so it is retained as a second valid pareiasaur from the Chinese latest Permian. 26 15 Phylogenetic analysis confirms the validity of these two taxa, with Sanchuansaurus belonging 27 28 16 among the basal forms, and Shihtienfenia being a member of the derived clades Velosauria 29 30 17 and Therischia, part of the new clade Sinopareiasauria, sister to the derived Elginiidae and 31 18 Scutosaurus. 32 33 19 34 35 20 ADDITIONAL KEYWORDS: Permian, amniotes, Parareptilia, Changhsingian, Sunjiagou 36 21 Formation. 37 38 22 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Zoological Journal of the Linnean Society Page 2 of 85

2 1 2 3 23 INTRODUCTION 4 5 24 6 25 Pareiasaurs were a significant and unusual clade of Middle and Late Permian parareptiles, 7 8 26 having been key herbivores in many faunas. In certain locations in the Russian and South 9 10 27 African Permo-Triassic, pareiasaurs were the dominant animals, representing for example at 11 28 the upper Middle Permian (upper Capitanian) site of Kotel’nich in Russia some 52% of all 12 13 29 tetrapod skeletons recovered (Benton et al. 2012). They flourished from the Wordian to 14 15 30 Changhsingian, but died out during the Permo-Triassic mass extinction. Pareiasaurs are best 16 31 known from the Middle and Late Permian of South Africa (Lee et al. 1997) and Russia (Lee 17 18 32 2000; Tsuji 2013), Forwith several Review forms reported from China Only (Young & Yeh 1963; Gao 1983, 19 20 33 1989; Li & Liu 2013; Xu et al. 2015), and isolated taxa from Morocco (Jalil & Janvier 2005), 21 34 Niger (Tsuji et al. 2013), Brazil (Araújo 1985), Germany (Tsuji & Müller 2008), and 22 23 35 Scotland (Newton 1893). Pareiasaurs ranged in size from little more than 1 m to 3 m in body 24 25 36 length, and the larger animals were massively constructed and perhaps weighed a tonne in 26 37 life. These massive, sprawling herbivores, with bony armour plates in their skin, were 27 28 38 probably preyed on by sabre-toothed gorgonopsians, but otherwise presumably had few 29 30 39 predators. Although interpreted as largely aquatic by some authors, finds of fossil footprints, 31 40 and the taphonomy of their burial, suggests a primarily terrestrial lifestyle (Benton et al. 32 33 41 2012), a suggestion confirmed by stable isotope studies of pareiasaur teeth and bones 34 35 42 (Canoville et al. 2014). 36 43 An unusual aspect of pareiasaurs is that they were identified as an outgroup, even the 37 38 44 sister group, of turtles by Lee (1993, 1995, 1996, 1997), based on their shared characters of a 39 40 45 rigid covering of dermal armour over the entire dorsal region, expanded flattened ribs, a 41 46 cylindrical scapula blade, great reduction in humeral torsion (to 25°), a greatly developed 42 43 47 trochanter major, an offset femoral head, and a reduced cnemial crest of the tibia. This was 44 45 48 disputed by other morphological phylogenetic analyses (e.g. Rieppel & deBraga 1996; 46 49 deBraga & Rieppel 1997; Rieppel & Reisz 1999; Li et al. 2009) that indicated a pairing of 47 48 50 turtles and lepidosauromorphs among the diapsids, and by molecular phylogenetic studies of 49 50 51 modern reptiles that repeatedly placed turtles among the Diapsida, and the Archosauromorpha 51 52 in particular (e.g. Hedges and Poling 1999; Field et al. 2014). New finds of the Triassic proto- 52 53 53 turtles Pappochelys and Odontochelys show close links to the Middle Permian Eunotosaurus, 54 55 54 and turtles are confirmed as archosauromorphs on the basis of fossil and molecular data, and 56 55 not related to pareiasaurs (Joyce 2015; Schoch and Sues 2015). 57 58 56 59 60 Page 3 of 85 Zoological Journal of the Linnean Society

3 1 2 3 57 Pareiasaurs have been reported from the Late Permian of China in several papers, with 4 5 58 six genera and species so far named from two geological formations, the Shihezhi Formation 6 59 of Henan Province (Honania complicidentata, Tsiyuania simpicidentata), and the Sunjiagou 7 8 60 Formation of Shanxi Province (Shihtienfenia permica, Shansisaurus xuecunensis, 9 10 61 Huanghesaurus liulinensis, Sanchuansaurus pygmaeus). The aims of this paper are to present 11 62 comprehensive descriptions of all the Chinese pareiasaurs so far described, to determine the 12 13 63 likely validity of the various named taxa, and to consider their phylogenetic position in 14 15 64 comparison with pareiasaurs from other parts of the world. A final aim is to review their 16 65 stratigraphic occurrences, and compare these with pareiasaurs from elsewhere in the world. 17 18 66 For Review Only 19 20 67 INSTITUTIONAL ABBREVIATIONS 21 68 22 23 69 CAGS, Chinese Academy of Geological Sciences, Beijing, China; IVPP, Institute of 24 25 70 Vertebrate Paleontology and Paleoanthropology, Beijing, China. 26 71 27 28 72 29 30 73 GEOGRAPHIC AND STRATIGRAPHIC DISTRIBUTION OF THE CHINESE 31 74 PAREIASAURS 32 33 75 34 35 76 The localities for the Shihezi Formation pareiasaurs from Henan are described by Liu et al. 36 77 (2014) and Xu et al. (2015), and so will not be further discussed. The Sunjiagou Formation 37 38 78 pareiasaurs come from two sections along the banks of the Yellow River (Huanghe) and its 39 40 79 tributary, the Sanchuan River (Fig. 1), namely Baode and Liulin Counties, parts respectively 41 80 of Xinzhou City and Lüliang Prefectures, in the Province of Shanxi, to the west of Beijing, 42 43 81 China. 44 45 82 The type material of Shihtienfenia permica Young & Yeh, 1963 came from the ‘Upper 46 83 Permian from the vicinity of Lishenglen, Paote, N. W. Shansi, near the banks of the Huangho 47 48 84 (= Yellow) River’. In modern pinyin transliteration of the Chinese characters, these latter 49 50 85 names become Baode, Shanxi, and Huanghe. The stratigraphic section, including the find spot 51 86 of the fossils (Young & Yeh 1963: fig. 1), extends from Baode to Huayuan, ‘along the south 52 53 87 bank of the Huangho’. The place name ‘Lishenglen’ cannot be found on Google-Maps, but 54 55 88 Baode is located in Baode County, near Xinzhou City, on the east bank of Huanghe, at 56 89 coordinates 39.032N, 111.114E (Fig. 1). 57 58 59 60 Zoological Journal of the Linnean Society Page 4 of 85

4 1 2 3 90 The other three Shanxi pareiasaurs are from Liulin County, near Xuecunzhen (= 4 5 91 Xuecun town). Shansisaurus xuecunensis is from Tianjialing village, near Xuecun (Cheng 6 92 1980: 115), and Sanchuansaurus pygmaeus and the other pareiasaur bones reported by Gao 7 8 93 (1989: 1234) are also ‘from a locality near Tianjialing village, Liulin County’. The find site of 9 10 94 Huanghesaurus liulinensis seemed less clear from Gao’s (1983) description, but Li and Liu 11 95 (2013: 199–200) state that it was from the same location. It turns out that Tianjialing village 12 13 96 no longer exists – it was a former habitation of the Tian family (Tianjialing means ‘Tian 14 15 97 family hill’), located at coordinates 37.410N, 110.811E, but the fossil site (37.412757N, 16 98 110.815922E), as confirmed by Li and Liu (2013: 200), lies at the top of the cliff on the south 17 18 99 bank of the SanchuanFor River, opposite Review the G307 road, east Only of the bridge leading to Beigou 19 20 100 village, and to the west of the G20 expressway bridge that crosses the Sanchuan valley, and 21 101 just above a water tank for Beigou village, which carries the label ‘Tianjialing’ (as noted 22 23 102 during fieldwork in July 2015). 24 25 103 Fossil vertebrates have been identified at several levels from the terrestrial Permian of 26 104 north China, but the finds are sporadic and the stratigraphy not well confirmed. Key levels are 27 28 105 those of the Dashankou and Jiyaun faunas, dated as Roadian and Wuchiapingian respectively 29 30 106 (Fig. 2). The Jiyuan fauna, with Honania and Tsiyuania, comes from the Upper Shihezhi 31 107 (formerly Shihhotse) Formation, of Henan Province in northern China (Fig. 2), which dates 32 33 108 from the lower Capitanian to upper Wuchiapingian, based primarily on magnetostratigraphy 34 35 109 (Embleton et al. 1996; Stevens et al. 2011). The Jiyuan Fauna is from near the top of the unit, 36 110 and is dated as late Wuchiapingian (Liu et al. 2014). 37 38 111 The other pareiasaurs come from the Sunjiagou (formerly Shiqianfeng or 39 40 112 Shihtienfeng) Formation, part of the Shiqianfeng Group (reviewed by Mueller et al. 1991; 41 113 Stevens et al. 2011), a succession of more than 1000 m of red, brown, and purple claystones 42 43 114 and sandstones, interpreted as generally deposited in arid conditions, which is confirmed by 44 45 115 the occurrence of gypsum in lower units and fine-grained aeolian sandstones in the upper 700 46 116 m (Norin 1922; Wang & Wang 1986; Wang & Chen 2001). Fossils are rare throughout, with 47 48 117 plant fossils in upper parts, suggesting reductions in wetland floras towards the Permo- 49 50 118 Triassic boundary (Wang 1993; Wang & Chen 2001; Stevens et al. 2011). 51 119 Earlier Chinese authors could compare their tetrapod finds with the Russian and South 52 53 120 African (Karoo) sequences, which themselves lacked any independent age control. For 54 55 121 example, Young & Yeh (1963: 211-212) compared Shihtienfenia with Scutosaurus from 56 122 Russia and Propappus and Pareiasaurus from South Africa, equivalent respectively to the 57 58 123 Russian lower Vyatkian (Zone IV) and the Cistecephalus Zone of the Karroo (Fig. 2). Cheng 59 60 Page 5 of 85 Zoological Journal of the Linnean Society

5 1 2 3 124 (1980) confirmed these comparisons with respect to his Shansisaurus material, as did Gao 4 5 125 (1983) with respect to Huanghesaurus. In more detail, Gao (1989:1239-1240) developed 6 126 these ideas, splitting the Sunjiagou pareiasaurs into two geological age categories: 7 8 127 Sanchuansaurus from the lowest part of the Shanxi redbed sequence, was ‘at the same 9 10 128 evolutionary stage as Pareiasuchus’, and so this unit correlated best with the Cistecephalus 11 129 Zone of South Africa. The other three Chinese pareiasaurs came from higher in the Sunjiagou 12 13 130 Formation, and showed greatest similarity with Scutosaurus from the upper part of Zone IV in 14 15 131 Russia, and the Daptocephalus Zone (= now, Dicynodon Zone) of South Africa. If these 16 132 correlations were correct, the Sunjiagou Formation would span from mid Wuchiapingian 17 18 133 (Cistecephalus AssemblageFor Zone) Review to Changhsingian (Daptocephalus Only = Dicynodon 19 20 134 Assemblage Zone), and a similar age range for upper parts of the old Russian Zone IV (= 21 135 Sokolki; Vyatkian) (Fig. 2; Benton 2012; Benton et al. 2012). 22 23 136 The pareiasaurs occurred at different levels in the Sunjiagou Formation. Shihtienfenia 24 25 137 was located in the lower part of the formation, at the top of Unit II, a 40 m thick unit of 26 138 intercalated red mudstones and sandstones (Young & Yeh 1963). Huanghesaurus was 27 28 139 reported from ‘the topmost part of the Shihtienfeng Formation’ (Gao 1983. Gao (1989: 1239) 29 30 140 noted that the fossiliferous lens with Sanchuansaurus occurred in the ‘lowest part’ of the 31 141 Shihtienfeng (= Sunjiagou) Formation, and he is clear that this was below the levels at which 32 33 142 Shihtienfenia, Shansisaurus, and Huanghesaurus had been found. These uppermost and lower 34 35 143 levels are confirmed by Li and Liu (2013: 199–200). The three levels are discriminated in the 36 144 summary stratigraphic chart (Fig. 2), but their exact horizons are uncertain. 37 38 145 Debates about the relative ages of the tetrapods can be resolved only by independent 39 40 146 dating. Palaeobotanists and palynologists date the Sunjiagou Formation as late Late Permian, 41 147 and the overlying Liujiaggou and Heshanggou Formations as Early Triassic (Wang & Wang 42 43 148 1986; Hou & Ouyang 2000; Wang & Chen 2001; Stevens et al. 2001; Zhang et al. 2012). For 44 45 149 example, Zhang et al. (2012) describe the Sunjiagou Formation as about 200 m thick, and 46 150 correlated with the entirety of the Changhsingian stage, with roughly equal Lower, Middle, 47 48 151 and Upper divisions. Stevens et al. (2011) concur, and show the underlying Upper Shihezhi 49 50 152 Formation as extending from the base of the Capitanian to the top of the Capitanian or to the 51 153 late Wuchiapingian; in either interpretation, there is a hiatus below the Sunjiagou Formation. 52 53 154 The Lower Shihezhi (= Xiashihezhi) Formation lies below, extending from late Kungurian to 54 55 155 the end of the Wordian, and the Shanxi Formation lies below that (Fig. 2). Stevens et al. 56 156 (2011) note that palynology is a good guide to dating the Lower Permian terrestrial units, but 57 58 157 not for the Middle or Upper Permian units. Magnetostratigraphy provides some confirmation 59 60 Zoological Journal of the Linnean Society Page 6 of 85

6 1 2 3 158 of ages (Embleton et al. 1996; Menning and Jin 1998), with the Illawarra Reversal located in 4 5 159 the lower part of the Upper Shihezhi Formation, so dating that horizon as uppermost Wordian 6 160 or lowest Capitanian (Fig. 2). Intense reversals throughout the Upper Shihezhi and Sunjiagou 7 8 161 formations confirm they are all Illawarra in age (i.e. Capitanian to Changhsingian). Matching 9 10 162 of the Illawarra magnetostratigraphic signature gives two models for the ages of these units, 11 163 implying a larger or smaller gap between the Upper Shihezhi Formation and the Sunjiagou 12 13 164 Formation, and making the former unit either 5 or 10 Myr in duration. The overlying 14 15 165 Sunjiagou Formation has been dated as entirely Changhsingian, terminating arbitrarily at the 16 166 Permo-Triassic boundary (Embleton et al. 1996; Stevens et al. 2011). Even so, the 17 18 167 Changhsingian lastedFor about 2 MyrReview (254.1-252.2 Myr; ShenOnly et al. 2011), perhaps time for 19 20 168 some moderate differentiation among amniote faunas. 21 169 22 23 170 24 25 171 THE UPPER SHIHEZHI FORMATION PAREIASAURS 26 172 27 28 173 The pareiasaur taxa from the Upper Shihezi Formation of Henan, Honania complicidentata 29 30 174 and Tsiyuania simplicidentata, are presented briefly, as they have been redescribed and their 31 175 materials augmented by Xu et al. (2015). 32 33 176 The three original specimens of Honania are isolated teeth, each consisting of the 34 35 177 crown and part of the root (Fig. 3; Table 1). A fourth specimen tabulated by Young 36 178 (1979:103) is currently missing. IVPP V4015.1 (Fig. 3A, C; Young 1979: fig. 4, left) is well 37 38 179 preserved, and shows the cingulum and serrations clearly. The tooth is 25 mm long in all. The 39 40 180 root measures 6 x 7 mm in section, and it is not exactly circular, being slightly twisted and 41 181 with rather flat antero-posterior sides. The cingulum (Fig. 3A, ci) carries about 12 small 42 43 182 serrations, but they are abraded, and the margin of the crown carries eight very distinct 44 45 183 serrations up each side, making a total of 16. The crown portion, as delimited by the 46 184 cingulum, measures 13 mm dorsoventrally high and 10 mm anteroposteriorly wide. IVPP 47 48 185 V4015.2 (Fig. 3C; Young 1979: fig. 4, centre) is still in the rock, a deep purple-coloured 49 50 186 coarse sandstone containing bone and scale fragments, and is visible only in external (lateral/ 51 187 labial) view. The root is missing, and the crown shows eight denticles on one margin, six on 52 53 188 the other, suggesting a total of 15-17. The third specimen, IVPP V4015.3 (Fig. 3B, C; Young 54 55 189 1979: fig. 4, right) is smaller than the other two, being 18 mm long in all, and has a shorter 56 190 root that is waisted at mid-height, and appears roughly circular in cross section, measuring 57 58 191 about 7 x 8 mm. The cingulum and marginal denticles are partly abraded, but there seem to be 59 60 Page 7 of 85 Zoological Journal of the Linnean Society

7 1 2 3 192 about 12 small denticles on the cingulum, and 5-7 denticles on each crown margin. Each of 4 5 193 the marginal denticles is at the end of a distinct longitudinal ridge that may be seen traversing 6 194 the lingual and labial faces of the tooth. 7 8 195 The original materials of Tsiyuania (IVPP V4016; Fig. 3D) are currently missing, but 9 10 196 Young (1979: 103, fig. 5) shows two specimens out of five whose measurements he tabulates. 11 197 These two teeth are much larger than the teeth of Honania, apparently measuring 13 and 16 12 13 198 mm anteroposteriorly wide, and 21 and 25 mm dorsoventrally tall. In both illustrated 14 15 199 examples, the margins are badly damaged, and the full height and width of the crowns cannot 16 200 be measured accurately (Table 1). Further, it is hard to estimate the numbers of cingular and 17 18 201 marginal denticles.For Young (1979:103) Review included some much Only smaller, but unillustrated, teeth in 19 20 202 this taxon, with total heights of 15, ?9, and 8 mm, and it is not clear how the nine pareiasaur 21 203 teeth in all were divided between two taxa, nor what their diagnostic characters are. 22 23 204 These two pareiasaur taxa have rarely been mentioned in the literature. Lee (1997: 24 25 205 287) suggested they were upper (Tsiyuania) and lower (Honania) teeth of the same taxon, but 26 206 most authors either ignored the two genera, or declared they were nomina nuda (e.g. Li 2001). 27 28 207 Liu et al. (2014), in brief, and then Xu et al. (2015), in more detail, proposed that Honania 29 30 208 complicidentata was indeed valid, and synonymized Tsiyuania simplicidentata with it. They 31 209 identified additional pareiasaurian teeth among the other fossils described by Young (1979), 32 33 210 and also assigned additional elements collected in 2010 to this taxon, including a maxilla and 34 35 211 dentary, some other skull bones, vertebrae, ribs, and limb and girdle elements. 36 212 Xu et al. (2015) argue that the expanded materials of Honania confirm that it is a 37 38 213 distinctive taxon. They characterize it as having ‘maxillary teeth with high crowns, dentary 39 40 214 teeth slightly posteriorly inclined compared to the dentary dorsal margin, nearly all preserved 41 215 marginal teeth have a cusped cingulum on the lingual surface, and humerus without an 42 43 216 ectepicondylar foramen’. The tooth characters are general to all or most pareiasaurs, but the 44 45 217 absence of an ectepicondylar foramen, if confirmed, would distinguish Honania from all other 46 218 pareiasaurs. However, in their discussion, Xu et al. (2015) do not compare their Honania 47 48 219 material with Sanchuansaurus, regarding this genus as a synonym of Huanghesaurus and 49 50 220 Shansisaurus, a view not taken here. The only comparable elements are the maxilla and 51 221 femur: the maxilla and teeth of Honania seem identical to those of Sanchuansaurus, and both 52 53 222 femurs are similar enough, but both are incomplete, so a final view on synonymy cannot be 54 55 223 given. 56 224 57 58 225 59 60 Zoological Journal of the Linnean Society Page 8 of 85

8 1 2 3 226 HOW MANY SUNJIAGOU FORMATION PAREIASAURS? 4 5 227 6 228 BACKGROUND 7 8 229 9 10 230 The pareiasaurs of the Sunjiagou Formation of Shanxi are: Shihtienfenia permica, named by 11 231 Young & Yeh (1963) on the basis of a partial postcranial skeleton (IVPP V2717) and a 12 13 232 second specimen consisting of 11 vertebrae and other fragments (IVPP V2718); Shansisaurus 14 15 233 xuecunensis, named by Cheng (1980) for some isolated vertebrae, a scapulocoracoid, 16 234 humerus, and femur (CAGS V301); Huanghesaurus liulinensis, established by Gao (1983) for 17 18 235 an incomplete skeleton,For comprising Review a right lower jaw and Only a large number of vertebrae and 19 20 236 limb bones (IVPP V6722); and Sanchuansaurus pygmaeus named by Gao (1989) for a 21 237 maxilla and isolated postcranial remains (IVPP V6723-5). 22 23 238 There are three viewpoints on the taxonomic validity of these four taxa: (1) to 24 25 239 synonymise them all with Shihtienfenia permica Young & Yeh, 1963, the first-named taxon, 26 240 on the basis that the other three species show no distinguishing characters; (2) to accept three 27 28 241 taxa as valid, by synonymising Huanghesaurus with Shansisaurus; or (3) to accept two taxa 29 30 242 as valid, by synonymising Huanghesaurus and Sanchuansaurus with Shansisaurus, and 31 243 retaining Shihtienfenia. 32 33 244 The first view, in which all taxa are synonymised, was presented by Sun et al. (1992) 34 35 245 and Lucas (2001). These authors noted that Cheng (1980) distinguished his new genus and 36 246 species Shansisaurus xuecunensis from Shihtienfenia by its supposedly more robust humerus, 37 38 247 a view they disputed. Further, they noted that Gao (1983) did not mention any diagnostic 39 40 248 characters to differentiate his new genus and species Huanghesaurus liulinensis from the two 41 249 earlier named taxa. Accordingly, Sun et al. (1992) synonymised Shansisaurus xuecunensis 42 43 250 and Huanghesaurus liulinensis with Shihtienfenia permica, a view with which Lucas (2001) 44 45 251 agreed. These authors did not comment on the fourth taxon, Sanchuansaurus pygmaeus. 46 252 Sanchuansaurus pygmaeus was named by Gao (1989), in his description of a variety 47 48 253 of pareiasaur materials from a single locality. He assigned a maxilla, a femur, and a fibula to 49 50 254 the new species Sanchuansaurus pygmaeus (IVPP V6723-5), and other postcranial remains to 51 255 Shansisaurus sp. (IVPP V6726-7) and to ‘Pareiasauride gen. et sp. indet.’ (IVPP V8533-5). 52 53 256 The only reasons given for not associating all these specimens into a single taxon, despite the 54 55 257 fact that they were all found within a single sandstone lens, is ‘the striking difference in size 56 258 and thickness of the bones, as well as their disarticulation’ and the fact that some, such as the 57 58 259 maxilla, are in very good condition, whereas some of the postcranial bones show signs of 59 60 Page 9 of 85 Zoological Journal of the Linnean Society

9 1 2 3 260 abrasion and transport. Here, and in line with earlier work by Lee (1997) and others, all the 4 5 261 materials described by Gao (1989) as from the same sedimentary lens are treated tentatively 6 262 as associated with the type maxilla of Sanchuansaurus. 7 8 263 The second view was presented by Lee (1997: 209), who regarded Shihtienfenia, 9 10 264 Shansisaurus, and Sanchuansaurus as valid, and synonymised Huanghesaurus with 11 265 Shansisaurus. These he characterised as follows: 12 13 266 1. Shihtienfenia permica. “Monophyletic. Autapomorphies: there is a rounded 14 15 267 expansion on the anterior margin of the scapula blade, near the dorsal end; and the 16 268 acromion process is a smoothly contoured, semicircular flange. Material: IVPP 17 18 269 V2717 (Type),For IVPP V8533.”Review Only 19 20 270 2. Shansisaurus xuecunensis. “Metaspecies. This species... differs from Shihtienfenia in 21 271 lacking the autapomorphies of the latter, and in possessing an ectepicondylar 22 23 272 foramen. Material: CAGS V301 (Type); IVPP V6722.” 24 25 273 3. Sanchuansaurus pygmaeus. “Monophyletic. Autapomorphies: the two exits for the 26 274 infraorbital canal are very far apart; and every tooth has a cusped cingulum on the 27 28 275 lingual surface. Material: IVPP V6723 (Type).” 29 30 276 This view was accepted by Jalil & Janvier (2005), Tsuji & Müller (2008), Tsuji (2013), and 31 277 Tsuji et al. (2013), who retained these three as separate taxa for cladistic coding, and found 32 33 278 close phylogenetic links between the first two and Pareiasuchus, but that Sanchuansaurus 34 35 279 formed part of a more derived clade, with Scutosaurus and Elginia, characterised by a single 36 280 synapomorphy, a cusped cingulum, a horizontal ridge that bears a row of small cusps on the 37 38 281 medial surface of some teeth (Character 64). 39 40 282 The third view was presented by Li & Liu (2013), who described new material from 41 283 the Sunjiagou Formation, and synonymised Sanchuansaurus and Huanghesaurus with 42 43 284 Shansisaurus xuecunensis based on supposed identity of the teeth of the first two. 44 45 285 46 286 COMMENTARY ON SUPPOSED DISTINGUISHING FEATURES 47 48 287 49 50 288 The one synonymy agreed generally is that Huanghesaurus is the same as Shansisaurus. The 51 289 only element preserved for both taxa, the scapulocoracoid, is identical in Shansisaurus 52 53 290 (Cheng 1980: fig. 19) and Huanghesaurus (Gao 1983: fig. 4), in terms of size, overall shape, 54 55 291 relative proportions, and anatomical details. 56 292 The question then is whether Shansisaurus (incl. Huanghesaurus) could be the same 57 58 293 as Shihtienfenia or not. Lee (1997: 209) noted that Shansisaurus ‘differs from Shihtienfenia in 59 60 Zoological Journal of the Linnean Society Page 10 of 85

10 1 2 3 294 lacking the autapomorphies of the latter, and in possessing an ectepicondylar foramen’. There 4 5 295 is no Shansisaurus humerus, so the reference is to Huanghesaurus, but it has no 6 296 ectepicondylar foramen, but in fact a possible entepicondylar foramen (this was a misprint, 7 8 297 and is presented correctly by Lee, 1997: 255). In any case, an ectepicondylar foramen is said 9 10 298 to be ‘universally present in pareiasaurs’ (Lee 1997: 237), whereas an entepicondylar foramen 11 299 is present in basal amniotes, and is retained by many pareiasaurs, but it ‘is an open groove in 12 13 300 Pareiasuchus peringueyi and Shihtienfenia’ (Lee 1997: 237). This is a dubious character upon 14 15 301 which to differentiate Shansisaurus and Shihtienfenia because the purported entepicondylar 16 302 foramen on the left humerus of Huanghesaurus (IVPP V6722-26) is superficial in location, 17 18 303 being bridged by theFor thinnest ofReview arches, and indeed this regionOnly has been substantially repaired, 19 20 304 and most of the ‘bone’ bridge is plaster. 21 305 Close comparison of the two most complete Chinese pareiasaur individuals, the 22 23 306 holotypes of Shihtienfenia permica (IVPP V2717) and Huanghesaurus liulinensis (IVPP 24 25 307 V6722), reveals four possible differentiating characters: (1) in posterior dorsal vertebrae of 26 308 Shihtienfenia there are ventral facets that each occupy one third of the vertebral length formed 27 28 309 from deeply overturned articular faces, and these are not seen in Huanghesaurus; (2) the rib 29 30 310 attachment facets in middle and posterior dorsal vertebrae of Shihtienfenia are shorter and 31 311 more massive; (3) the right scapula has an elongate, almost cylindrical blade ending in a 32 33 312 rounded, spoon-shaped distal end which expands especially on the anterior margin; and, (4) 34 35 313 the humerus is of conservative design and lacks the flared proximal end seen in 36 314 Huanghesaurus. The first two characters are hard to confirm because the numbering of 37 38 315 presacral vertebrae is debatable in both taxa, and those differential features might be minor 39 40 316 variations or size-related phenomena. The scapula characters, the basis of the two 41 317 autapomorphies of Shihtienfenia cited by Lee (1997: 209), namely the ‘rounded expansion on 42 43 318 the anterior margin of the scapula blade, near the dorsal end’ and ‘the acromion process is a 44 45 319 smoothly contoured, semicircular flange’, certainly occur in the figured right scapula (Young 46 320 & Yeh 1963: fig. 6), but they are absent in the left scapula, which is indistinguishable from 47 48 321 that of Shansisaurus, Huanghesaurus, and many other pareiasaurs – the blade has no rounded 49 50 322 distal portion, and the acromion process is of normal shape. However, the left scapula (IVPP 51 323 V2717) is incomplete distally and so the ‘rounded expansion’ cannot be considered. These 52 53 324 ‘autapomorphies’ apply to the right scapula only, and there is little doubt, both from Young & 54 55 325 Yeh’s (1963) description of the circumstances of discovery, and the nature of the specimens, 56 326 that these are parts of the body of a single individual. The two scapular autapomorphies of 57 58 327 Shihtienfenia (Lee 1997: 209) reflect morphological variation between left and right sides 59 60 Page 11 of 85 Zoological Journal of the Linnean Society

11 1 2 3 328 within a single individual, and so must be discarded. The fourth character, the flared proximal 4 5 329 end of the humerus in Huanghesaurus, may be exaggerated by the mode of preservation, and 6 330 so is not a reliable difference. 7 8 331 So far, the balance of evidence favours the view of Sun et al. (1992) and Lucas (2001) 9 10 332 that Shansisaurus and Huanghesaurus are junior synonyms of Shihtienfenia. This leaves the 11 333 fourth taxon, Sanchuansaurus pygmaeus to be considered. 12 13 334 14 15 335 SANCHUANSAURUS, DISTINCTIVE TOOTH MORPHOLOGY 16 336 17 18 337 The suggestion willFor be made here, Review in support of the view Only presented by Gao (1989), but 19 20 338 against Li & Liu (2013), that Sanchuansaurus, limited to the three specimens he assigned to 21 339 the taxon (IVPP V6723, V6724, V6725), is a distinct pareiasaur genus and species. Key 22 23 340 evidence is the lower number of marginal cusps in tooth crowns (9-11), and less significant 24 25 341 evidence is the smaller size of the animal and its greater stratigraphic age. These points will 26 342 be considered in turn. First, we consider other potential distinguishing characters. 27 28 343 One of the two autapomorphies of Sanchuansaurus noted by Lee (1997: 209), ‘the 29 30 344 two exits for the infraorbital canal [on the maxilla] are very far apart’, may be distinct from 31 345 other pareiasaurs with maxillae preserved, but it cannot be checked in the other Chinese 32 33 346 pareiasaurs because they lack this element. Gao (1989: 1234) distinguished Sanchuansaurus 34 35 347 from all other pareiasaurs based on the following combination of characters: “Maxillary short 36 348 and deep, with robust antorbital process and palatal flange. Teeth closely and firmly 37 38 349 implanted in maxillary; roots curved medially. Tooth crowns slightly compressed 39 40 350 transversely, markedly overlapping with each other; cusps, numbering 9-11, arranged as 3-4 41 351 anteriorly, 3 in middle, and 3-4 posteriorly.” In fact, these characters occur in nearly all 42 43 352 pareiasaurs. 44 45 353 There is a key difference in the teeth, in terms of the number of tooth cusps, a 46 354 phylogenetically important character (Lee 1997), ‘and every tooth has a cusped cingulum on 47 48 355 the lingual surface’ in Sanchuansaurus. In addition, Gao (1989: 1238) had noted that the 49 50 356 maxillary teeth of Sanchuansaurus have fewer serrations in total (10-12) than the dentary 51 357 teeth of Huanghesaurus (14-17). In all cladistic analyses so far (Lee 1997; Jalil & Janvier 52 53 358 2005; Tsuji & Müller 2008; Tsuji 2013; Tsuji et al. 2013), Sanchuansaurus is separated 54 55 359 phylogenetically from Shihtienfenia and Shansisaurus, partly as a result of the difference in 56 360 marginal cusp numbers in the teeth. Including all teeth, the figures are 9-12 denticles in 57 58 361 Sanchuansaurus and 13-17 in Huanghesaurus (Table 1). Li & Liu (2013) describe a tooth 59 60 Zoological Journal of the Linnean Society Page 12 of 85

12 1 2 3 362 (IVPP V18614) with 17 cusps, seemingly then an example of Huanghesaurus, but they note it 4 5 363 was found in association with the holotype of Sanchuansaurus, from the lower part of the 6 364 Sunjiagou Formation, and so synonymise the two genera, and those two with Shansisaurus. 7 8 365 However, this tooth cannot be unequivocally identified as Sanchuansaurus, and not 9 10 366 Huanghesaurus, and so does not prove a synonymy. 11 367 A second dental apomorphy is less clear. In the cladistic analyses (Lee 1997; Jalil & 12 13 368 Janvier 2005; Tsuji & Müller 2008; Tsuji 2013; Tsuji et al. 2013), Sanchuansaurus and 14 15 369 Scutosaurus are paired by possession of the unique apomorphy of a cusped cingulum, and 16 370 thereby distinguished from the other Chinese pareiasaurs. However, the possession of a 17 18 371 cingulum and of cingularFor denticles Review by Sanchuansaurus isOnly not unique among the Chinese 19 20 372 pareiasaurs. All dentary teeth of Huanghesaurus also show a clear cingulum, and it bears 21 373 several denticles in the marginal portions, as noted also by Li & Liu (2013: 202). These 22 23 374 features are presented in more detail below, and re-coded for the revised cladistic analysis. 24 25 375 It could be countered that there is a danger in these comparisons, because 26 376 Sanchuansaurus and Huanghesaurus are distinguished on differences between maxillary and 27 28 377 dentary teeth, and that pareiasaurs show differences in the size and shape of upper and lower 29 30 378 dentitions (Lee 1997: 215). For example, in Pareiasuchus nasicornis, the single dentary tooth 31 379 that can be seen differs in shape from the maxillary and premaxillary teeth in being taller, 32 33 380 possessing more cusps, having cusps that face somewhat anteriorly and posteriorly, and a 34 35 381 crown that is not recurved lingually, differential features seen also in Pareiasuchus peringueyi 36 382 and Scutosaurus karpinskii. However, such variation does not occur in all pareiasaurs: 37 38 383 Deltavjatia shows similar-sized teeth in both upper and lower dentitions (Tsuji 2013). 39 40 384 Further, these variations between upper and lower dentitions do not extend to cusp numbers. 41 385 Less significant is body size. The Sanchuansaurus maxilla and Huanghesaurus 42 43 386 dentary could hardly come from the same animal: the first possesses 15 teeth within a tooth- 44 45 387 row length of 135 mm, the latter possesses 19 teeth in a tooth-row length of 200 mm, 46 388 suggesting that, if upper and lower tooth row lengths should be comparable, and these two 47 48 389 tooth rows are more or less complete, that the Sanchuansaurus individual was about two- 49 50 390 thirds the linear dimensions of the Huanghesaurus animal, which could scale to one-third of 51 391 the body mass, assuming isometry (0.67 x 0.67 x 0.67 = 0.3). 52 53 392 The postcranial bones assigned to Sanchuansaurus by Gao (1989) include a partial left 54 55 393 femur (IVPP V6724) and a left fibula (IVPP V6725). The femur, although relatively 56 394 featureless, and indistinguishable from that of Shansisaurus (Cheng 1980: fig. 20), is 57 58 395 considerably shorter (270 mm, compared to 430 mm for a similar portion of the bone in 59 60 Page 13 of 85 Zoological Journal of the Linnean Society

13 1 2 3 396 Shansisaurus). Likewise the left fibula is smaller than expected, some 236 mm long, and in 4 5 397 proportion to the femur, although no fibula of the larger Chinese pareiasaurs is known, for 6 398 comparison. The other elements from the same bone-bearing lens, including a dorsal vertebra, 7 8 399 a right scapulocoracoid, a partial scapula blade, and the now lost left humerus and right tibia, 9 10 400 assigned variously by Gao (1989: 1238-1239) to Shansisaurus sp. and Pareiasaur indet., come 11 401 from larger animals, perhaps one-third larger, and similar in size to Shihtienfenia. Size is a 12 13 402 poor criterion for taxon discrimination, as is stratigraphic age, but Gao (1989: 1239) and Li 14 15 403 and Liu (2013: 199–200) note that Sanchuansaurus was older than the other Sunjiagou 16 404 Formation pareiasaurs. 17 18 405 For Review Only 19 20 406 21 407 SYSTEMATIC DESCRIPTIONS 22 23 408 24 25 409 ORDER PARAREPTILIA OLSON, 1947 26 410 SUBORDER PAREIASAURIA SEELEY, 1888 27 28 411 FAMILY PAREIASAURIDAE COPE, 1896 29 30 412 Comments: Here, we describe the two valid Sunjiagou Formation pareiasaurs, 31 413 Sanchuansaurus pygmaeus and Shihtienfenia permica. Several specimens were found to be 32 33 414 missing (May 2012), namely IVPP V2718 (paratype of Shihtienfenia, 11 dorsal vertebrae and 34 35 415 fragments, badly weathered; Young & Yeh 1963: 207); IVPP V4016 (holotype teeth of 36 416 Tsiyuania simplicidentata Young, 1979: 103-104, fig. 5); IVPP V8535 (pareiasaurid right 37 38 417 tibia in Gao 1989: 1239); CAGS V301 and V302 (holotype and paratypes of Shansisaurus 39 40 418 xuecunensis Cheng, 1980, scapulocoracoid, humerus, vertebrae, ribs, isolated teeth). 41 419 42 43 420 44 45 421 SANCHUANSAURUS GAO, 1989 46 422 47 48 423 Type species: Sanchuansaurus pugmaeus Gao, 1989. 49 50 424 Diagnosis: As for the type species. 51 425 Distribution: Shanxi Province, China; Upper Permian (Changhsingian). 52 53 426 54 55 427 SANCHUANSAURUS PYGMAEUS GAO, 1989 56 428 57 58 429 Sanchuansaurus pygmaeus Gao; Gao 1989: 1234-1238, fig. 1, pl. 1 59 60 Zoological Journal of the Linnean Society Page 14 of 85

14 1 2 3 430 Sanchuansaurus pygmaeus Gao; Lee 1997: 210 4 5 431 Sanchuansaurus pygmaeus Gao; Jalil & Janvier 2005: 115 6 432 Sanchuansaurus pygmaeus Gao; Tsuji & Müller 2008: 1118 7 8 433 9 10 434 Holotype - IVPP V6723, a right maxilla. 11 435 12 13 436 Paratypes - IVPP V6724, a left femur, and IVPP V6725, a left fibula. 14 15 437 16 438 Type locality and horizon - Beigou village, near Weicun town, Liulin County, Shanxi 17 18 439 Province, China; lowestFor part of Reviewthe Sunjiagou Formation, Only Upper Permian (Changhsingian). 19 20 440 21 441 Revised diagnosis - A pareiasaur, about one-third the body mass, and two-thirds the length, 22 23 442 of the other Sunjiagou Formation pareiasaurs, with 9-12 marginal cusps on maxillary teeth; 24 25 443 the two exits for the infraorbital canal [on the maxilla] are very far apart (Lee 1997: 209). 26 444 27 28 445 Maxilla - The holotype of Sanchuansaurus pygmaeus Gao, 1989 (IVPP V6723; Fig. 4) is 135 29 30 446 mm anteroposteriorly long and 85 mm dorsoventrally deep, and it is cracked and lacks the 31 447 most anterior and most posterior portions. The anterior end is massive and terminates in a 32 33 448 vertical portion, probably representing more or less the orientation of the premaxillary 34 35 449 contact. The narial margin of the maxilla is elongate and sweeps up and back into the 36 450 antorbital process (Fig. 4A, B, a.p.), which appears to be more or less complete, lacking 37 38 451 perhaps the dorsalmost portion. This process broadens into a distinct lateral boss, located 39 40 452 above maxillary teeth 5-7, an unusual feature among pareiasaurs, as noted by Gao (1989: 41 453 1235). The posterodorsal margin of the maxilla, which presumably contacted the lacrimal in 42 43 454 life, again lacks the thinner portions, but sweeps back and down to the relatively narrow 44 45 455 posterior portion of the maxilla, which would have met the jugal with a narrow process. The 46 456 ventral margin is more or less straight in lateral view (Fig. 4A), and bears the remains of 15 47 48 457 marginal teeth. These sit in distinct sockets which crowd closely, and somewhat irregularly on 49 50 458 the ventral margin. Around the teeth, and above them, is a zone, some 7-12 mm deep, of 51 459 somewhat porous-looking, unfinished bone surface that might represent actively replacing 52 53 460 bone tissue associated with the continuing tooth replacement. 54 55 461 The medial view of the maxilla (Fig. 4B) shows a substantial palatal shelf (Fig. 4B, C, 56 462 p.s.) running nearly horizontally, and more or less parallel to the ventral tooth-bearing margin. 57 58 463 The medial faces of the maxilla that lie above and below the palatal shelf are somewhat 59 60 Page 15 of 85 Zoological Journal of the Linnean Society

15 1 2 3 464 concave. The shelf is located halfway between the dorsal point of the antorbital process and 4 5 465 the ventral margin of the maxilla (80 mm), and it projects medially. The maxilla is about 15 6 466 mm thick above the tooth-bearing area, and with the shelf its overall thickness varies from 25- 7 8 467 30 mm and up to 35 mm at the position of the antorbital boss. The antorbital process (Fig. 4B, 9 10 468 a.p.) projects above, and below is the deep tooth-bearing area. Three replacement teeth have 11 469 been exposed in this zone, located above teeth 3-4, 6, and 8 respectively. The somewhat 12 13 470 irregular arrangement of the marginal teeth is clear in medial view (Fig. 4B), with numbers 3, 14 15 471 5, and 7 projecting more laterally than the others. In this area, teeth 3-7 are relatively large, 16 472 and there is insufficient space for them to form a uniform row, so presumably several were 17 18 473 forced out of line asFor they emerged Review into their final positions. Only As on the dorsal face, there is a 19 20 474 distinct zone, some 17-25 mm deep, above and round the functioning and the replacement 21 475 teeth, where the bone surface texture is porous or irregular. In places it shows vertically 22 23 476 oriented striations, which contrast with the more horizontal striation pattern in the finished 24 25 477 bone surface above. 26 478 The bone shows surprisingly few vessel openings, and no trace of the often abundant 27 28 479 small canals in the snout and gum region of other amniotes. The infraorbital canal is very 29 30 480 clear in medial view (Fig. 4B, io.c.), entering the maxilla above the palatine shelf, and just 31 481 behind the antorbital process, and perhaps exiting through two large openings on the lateral 32 33 482 face (Fig. 4A, io.c.). This canal presumably carried the infraorbital nerve, the anterior portion 34 35 483 of the maxillary branch of the trigeminal nerve (cranial nerve V2) as well as presumably the 36 484 infraorbital artery. 37 38 485 The teeth are of normal pareiasaur shape (Table 1), with a broad, somewhat diamond- 39 40 486 shaped crown and a narrower, smooth shaft. Each tooth emerges from the maxilla, expands 41 487 into the crown, and curves medially and slightly posteriorly. This gives the lateral (labial) face 42 43 488 of each tooth a distinct convex shape, with a definite medial bend at the transition from shaft 44 45 489 to crown. Tooth 2 is broken at the level of the maxillary margin, and it shows a more or less 46 490 circular cross section (Fig. 4C, 2), measuring 9 mm in the antero-posterior axis, and 8 mm 47 48 491 medio-laterally. The outer dentine wall is 2 mm wide, leaving a 4-5 mm wide central dentine 49 50 492 core. This central shaft of younger dentine is seen clearly in tooth 1, which has been partly 51 493 prepared out (Fig. 4B, 1). The tooth crown measures 7-12 mm in the antero-posterior axis, 52 53 494 compared to a shaft of 5-7 mm in the same orientation. The teeth vary slightly in size, 54 55 495 becoming slightly larger from front to back (Table 1). The crown extends to the distal margin 56 496 smoothly in lateral view (Fig. 4A), but there is a distinct cingulum and occlusal surface on the 57 58 497 medial (lingual) face (Fig. 4B). This medial crown surface bears no lingual ridge (Lee 1997: 59 60 Zoological Journal of the Linnean Society Page 16 of 85

16 1 2 3 498 fig. 11). The cingulum at the proximal margin of the occlusal surface is gently curved, 4 5 499 whereas the distal margin of the tooth is somewhat pointed, although most marginal teeth in 6 500 this specimen have been damaged. The cingulum bears 10-12 tiny serrations on the edge of 7 8 501 the occlusal surface (2.5 per mm), and at the outer edges, these serrations expand into the 9 10 502 most proximal of the major serrations that surround the biting edge of the tooth. Each tooth 11 503 bears 9-12 such marginal denticles, or cusps, each typically 1 mm wide, but some proximal 12 13 504 ones 1.5 mm wide, and separated by deep grooves on labial and lingual tooth faces; each 14 15 505 marginal serration then is 1-3 mm long, if the grooves are included. These marginal cusps 16 506 point essentially ventrally, parallel to the longitudinal axis of the tooth. 17 18 507 The anterodorsalFor margin Review of the maxilla indicates Only that Sanchuansaurus had an elongate 19 20 508 external naris (Lee 1997, character 23; Tsuji 2013, character 20); the maxilla shows a 21 509 prominent maxillary boss (Lee 1997, character 25; Tsuji 2013, character 26); the maxillary 22 23 510 dentition is inflected towards the palate, and the teeth are oriented ventromedially (Lee 1997, 24 25 511 character 27; Tsuji 2013, character 50); the number of maxillary teeth in each maxilla is more 26 512 than or equal to 10 (Lee 1997, character 55; Tsuji 2013, character 51); the teeth are 27 28 513 labiolingually compressed, leaf-shaped, and with small denticles on the tooth crown (Lee 29 30 514 1997, character 58; Tsuji 2013, character 52); cusps are regularly spaced along the tooth 31 515 crown (Lee 1997, character 61; Tsuji 2013, character 53); there are 9-11 marginal cusps on 32 33 516 each maxillary tooth (Lee 1997, character 59; Tsuji 2013, character 54); there is a cingulum 34 35 517 present, with small cuspules (Lee 1997, character 64; Tsuji 2013, character 57); and there is 36 518 no caniniform region in the tooth row (Tsuji 2013, character 120). 37 38 519 39 40 520 Femur - An incomplete left femur was assigned to Sanchuansaurus by Gao (1989: 1235- 41 521 1238, fig. 2, pl. 2A, B). The specimen (IVPP V6724) is 270 mm long at most (not 300 mm, as 42 43 522 stated by Gao 1989: 1235), and it lacks both articular ends, these being represented by 44 45 523 irregular broken faces and red sandstone infill (Fig. 5A-D). The irregular termination of the 46 524 element at both ends suggests that the epiphyses fell off before fossilisation, and even that the 47 48 525 exposed diaphyseal ends were somewhat damaged; perhaps the element comes from a young 49 50 526 animal in which the epiphyses had not fused. This femur may have been 290 mm or more in 51 527 length when complete. As in other pareiasaurs (Seeley 1892, figs. 8-11), this is a relatively 52 53 528 short element, with short diaphysis and expanded ends. The maximum width of the anterior 54 55 529 end is 112 mm, of the posterior end 115 mm, and minimum breadth of the shaft is 55 mm 56 530 (excluding the postaxial flange), all measured in dorsal view (Fig. 5A). The shaft is strong, 57 58 531 and it expands proximally as a convex face in dorsal view (Fig. 5A), extending posteriorly 59 60 Page 17 of 85 Zoological Journal of the Linnean Society

17 1 2 3 532 into a sizable postaxial flange (Fig. 5A, p.f.) that diminishes to a minimum thickness of 18 4 5 533 mm near the margin. Distally, the shaft expands to form a concave intercondylar sulcus (Fig. 6 534 5A, i.s.) towards the distal end. The intercondylar foramen in this sulcus is not seen, the 7 8 535 preserved bone terminating before that point. The distal condyles are missing, but the 9 10 536 preserved bone extends somewhat further on the anterior side, forming the proximal part of 11 537 the tibial condyle (Fig. 5A, ti.c.). In ventral/ medial view (Fig. 5B), the proximal 12 13 538 intertrochanteric fossa is broad and nearly symmetrical, and extends from the anterior margin 14 15 539 across the postaxial flange. The distal end is too incomplete to see the popliteal fossa or any 16 540 foramen in the fibular condyle, as indicated by Gao (1989: 1235, fig. 2B). 17 18 541 The proximalFor head of thisReview femur is curved slightly Only anteriorly (preaxially) (Lee 1997, 19 20 542 character 107; Tsuji 2013, character 95); the postaxial flange is present, and extends the entire 21 543 length of the femur, but is narrower in the middle, so the femur looks concave in dorsal or 22 23 544 ventral view (Lee 1997, character 112; Tsuji 2013, character 97). 24 25 545 26 546 Fibula - A complete left fibula was also referred to Sanchuansaurus pygmaeus by Gao (1989: 27 28 547 1235), but not illustrated. This element (IVPP V6725) is a straight bone, 236 mm long, and 29 30 548 with expanded proximal and distal ends, some 86 and 75 mm at their greatest widths 31 549 respectively (Fig. 5E–H). The shaft narrows to 30 x 38 mm. The proximal end is massive, 32 33 550 oval in shape in proximal view and measuring 62 x 85 mm. The shaft is roughly straight, with 34 35 551 minimal twisting so that the long axes of the articular ends are set at 30 degrees to each other. 36 552 The distal articular end is narrower, measuring 30 x 72 mm. The bone is broadest in extensor 37 38 553 (dorsal) and flexor (ventral) views (Fig. 5E, G), and it shows a clear anterior trochanter in 39 40 554 flexor and anterior views (Fig. 5G, H, a.t.), some 30 mm long, located entirely within the 41 555 proximal half of the bone. The anterior fibular ridge is slightly marked, but other muscle 42 43 556 attachment sites are less clearly demarcated. At the distal end, the facets for articulation with 44 45 557 the fibulare and intermedium (Fig. 5E, fib., int.) are separated by an angulation, and there is a 46 558 depressed area above these on the extensor face of the shaft. It seems that Gao (1989: 1235) 47 48 559 confused the proximal and distal articular ends in giving measurements. 49 50 560 51 561 SHIHTIENFENIA YOUNG & YEH, 1963 52 53 562 54 55 563 Type species - Shihtienfenia permica Young & Yeh, 1963 56 564 Diagnosis - As for the type species. 57 58 565 Distribution - Shanxi Province, China; Upper Permian (Changhsingian). 59 60 Zoological Journal of the Linnean Society Page 18 of 85

18 1 2 3 566 4 5 567 SHIHTIENFENIA PERMICA YOUNG & YEH, 1963 6 568 7 8 569 Shihtienfenia permica Young & Yeh; Young & Yeh 1963: 195-212, figs. 1-9, pls. 1, 2 9 10 570 Shansisaurus xuecunensis Cheng; Cheng, 1980: 115-119, figs. 18-20, pls. 127, 128; 11 571 subjective synonym 12 13 572 Shihtienfenia Young & Yeh; Gao 1983: 201 14 15 573 Shansisaurus Cheng; Gao 1983: 201 16 574 Huanghesaurus liulinensis Gao; Gao, 1983: 193-203, figs. 1-7, pls. 1, 2; subjective synonym 17 18 575 Shansisaurus xuecunesisFor Cheng; Review Gao 1989: 1238-1239, Onlyfig. 3 19 20 576 Huanghesaurus liulinensis Gao; Gao 1989: 1238 21 577 Shihtienfenia Young & Yeh; Lee 1995: 503 22 23 578 Shihtienfenia permica Young & Yeh; Lee 1997: 209 24 25 579 Shansisaurus xuecunensis Cheng, 1980; Lee 1997: 209 26 580 Shihtienfenia permica Young & Yeh; Lucas 2001: 79-80, fig. 6-8 27 28 581 Syn. Shansisaurus xuecunensis Cheng; Lucas 2001: 79 29 30 582 Syn. Huanghesaurus liulinensis Gao; Lucas 2001: 79-80 31 583 Shihtienfenia permica Young & Yeh; Jalil & Janvier 2005: 115 32 33 584 Shansisaurus xuecunesis Cheng; Jalil & Janvier 2005: 115 34 35 585 Shihtienfenia permica Young & Yeh; Tsuji & Müller 2008: 1118 36 586 Shansisaurus xuecunesis Cheng; Tsuji & Müller 2008: 1118 37 38 587 39 40 588 Holotype - IVPP V2717, a partial skeleton, consisting of about 20 vertebrae, ribs, and 41 589 elements of the pectoral girdle (scapulocoracoids, dermal pectoral elements), both humeri, 42 43 590 and both pelvic plates (ilium, pubis, ischium). 44 45 591 46 592 Paratypes - CAGS V301, isolated vertebrae, a complete left scapulocoracoid, a left femur, 47 48 593 and some rib fragments, the type material of Shansisaurus xuecunensis Cheng, 1980; CAGS 49 50 594 V302, vertebrae, assigned to Shansisaurus xuecunensis Cheng, 1980; IVPP 6722-1 to 29, an 51 595 incomplete skeleton, consisting of a left lower jaw, a possible jugal, part of the right lower 52 53 596 jaw, conjoined splenials, 13 vertebrae, the left scapulocoracoid, clavicles, interclavicle, and 54 55 597 the left humerus, ulna, and radius, the type specimen of Huanghesaurus liulinensis Gao, 56 598 1983. 57 58 599 59 60 Page 19 of 85 Zoological Journal of the Linnean Society

19 1 2 3 600 Type locality and horizon - Lishenglen, Baode town, Baode County, Shanxi Province, 4 5 601 China; Sunjiagou Formation, Upper Permian (Changhsingian). 6 602 7 8 603 Revised diagnosis - A pareiasaur, about three times the body mass, and 1.5 times the length, 9 10 604 of Sanchuansaurus, with 13-17 marginal cusps on maxillary teeth. Entepicondylar foramen of 11 605 humerus situated on the side of the epicondyle and feebly exposed in dorsal view, foramen 12 13 606 has migrated around the edge of the humerus (coded in Shihtienfenia and Huanghesaurus). 14 15 607 Possibly also intercondylar depression on the dorsal surface of the distal end of the humerus 16 608 with a transverse ridge present on the distal surface, defined dorsally by the ulnar articular 17 18 609 surface (seen in ShihtienfeniaFor, butReview not codable in Shansisaurus Only or Huanghesaurus). 19 20 610 21 611 22 23 612 SKULL AND LOWER JAW 24 25 613 26 614 POSSIBLE JUGAL 27 28 615 29 30 616 An isolated element, IVPP V6722-3, was identified by Gao (1983: 195, pl. 1, figs. 3, 4) as an 31 617 angular of Huanghesaurus, the descending boss from the left side of the lower jaw. This 32 33 618 identification, however, cannot be correct because the narrow process that is supposed to be 34 35 619 the descending boss, and so free of all contact with other bones, bears an articulating facet. 36 620 This specimen (Fig. 6) is reinterpreted here very tentatively as a left jugal. It is roughly-L- 37 38 621 shaped, with a long narrow process and, more or less at right angles, a wider process. These 39 40 622 two outline a curved margin on the inside of the L-shape that did not suture with anything, 41 623 and could then be the postero-ventral margin of the orbit. If this is the case, then the narrower 42 43 624 process is the anterior process that contacts the lacrimal with its anterior tip, and the maxilla 44 45 625 along most of the ventral margin. The broader process at right angles would then contact the 46 626 postorbital dorsally on the broad upper margin. The posterior margin of the element has an 47 48 627 upper portion that describes a distinctly concave surface in medial view (Fig. 6B), with a slot 49 50 628 or groove below. If correctly interpreted, these faces would mark contacts with the squamosal 51 629 above, and the quadratojugal below. An objection to this revised interpretation is that the 52 53 630 element bears little if any sculpture externally (Fig. 6A), whereas the jugal is liberally 54 55 631 sculpted in most pareiasaurs. However, there is a raised portion and a groove in the middle of 56 632 the lower portion of the broader process, and the distal region of this process is damaged, so 57 58 633 the external surface cannot be assessed. 59 60 Zoological Journal of the Linnean Society Page 20 of 85

20 1 2 3 634 4 5 635 MANDIBLE 6 636 7 8 637 The lower jaw is represented by three specimens, IVPP V6722-1 and 2, both ascribed to 9 10 638 Huanghesaurus by Gao (1983: fig. 1, pl. 1, figs. 1, 2, 5), and an unnumbered piece. 11 639 12 13 640 Mandible - IVPP V6722-1 (Fig. 7A–C) is a huge right lower jaw of a pareiasaur, seemingly 14 15 641 much larger than any of the associated remains. It appears to be complete except for the 16 642 splenial. The specimen is undistorted and preservation quality is excellent. In lateral view 17 18 643 (Fig. 7A), the jaw isFor remarkably Review equal in depth from front Only to back. The whole specimen 19 20 644 measures 364 mm in maximum length, along its ventral region from the posterior expansion 21 645 of the angular to the anterior symphyseal point. The dorsal margin, from articular to anterior 22 23 646 teeth insertions measures 273 mm. Depth of the jaw is 62 mm below tooth 2, 53 mm below 24 25 647 tooth 3, 81 mm at the back of the tooth row, and 96 mm measured vertically from the high 26 648 point in front of the articular facet. The specimen evidently broke in two, and this has been 27 28 649 repaired by IVPP technicians, so the specimen can be displayed. Close inspection suggests 29 30 650 that this line of break roughly marks the posterior margin of the dentary in lateral and medial 31 651 views. 32 33 652 The dentary is by far the largest element of the lower jaw, comprising 60% of its 34 35 653 length ventrally and nearly 90% dorsally. In lateral view (Fig. 7A), the dentary is a broad 36 654 strap-like plate that curves slightly from the symphyseal portion, and its ventral margin 37 38 655 sweeps back in a straight line. Here the edge is very thin, tapering to nothing where it would 39 40 656 have overlapped the absent splenial. This ventral margin angles slightly upwards posteriorly, 41 657 exposing the anterior process of the angular in lateral view, and it then bends more dorsally 42 43 658 into its posterior margin, also presumably wafer-thin, but obscured by repair medium, and 44 45 659 presumably running to a point at the postero-dorsal angle. The dorsal margin of the dentary is 46 660 closely lined with teeth from its most medial point above the symphysis, back some 200 mm, 47 48 661 leaving only 45 mm or so of toothless dorsal margin behind (exact distance obscured by 49 50 662 repair medium). In the space of 200 mm are 19 teeth, numbers 1-15 more or less complete (3 51 663 is a pit), and 16-18 represented by broken-off roots, and tooth 19 by a pit (Fig. 7A–C). Gao 52 53 664 (1983: 203) noted 20 teeth. Tooth 3 is represented by a pit, as if it had been shed, and not 54 55 665 replaced, just before death. Tooth 11 is set lower than the others, and is perhaps just emerging 56 666 from the jaw line and moving into place. Otherwise, the intact teeth form a regular palisade, 57 58 667 all reaching the same level dorsally, and so providing a uniform cutting blade. There are three 59 60 Page 21 of 85 Zoological Journal of the Linnean Society

21 1 2 3 668 large vessel openings (Fig. 7A, v.o.) at mid-height on the lateral face of the dentary, 4 5 669 measuring 8, 10, and 7 mm respectively in maximum antero-posterior length respectively 6 670 fromfront to back. These canal openings lie below tooth positions 3, 7, and 9, and they 7 8 671 presumably housed exiting mental nerves and blood vessels. 9 10 672 The dentary forms part of the symphysis (Fig. 7B, sy.), on a flattened vertical face that 11 673 consists of the lateral plate and a medial plate below the tooth row, each at most 12 mm thick 12 13 674 medio-laterally. The lateral plate descends 65 mm below the first tooth, whereas the medial 14 15 675 plate descends 50 mm, diverging from the lateral plate, and leaving a shallow roofed channel 16 676 beneath, the anteriormost portion of the Meckelian fossa. In medial view posterior to the 17 18 677 symphysis (Fig. 7B),For the ventral Review margin of the medial plateOnly runs back for some 90 mm above 19 20 678 an open Meckelian fossa (Fig. 7B, me.f.) below which would have been covered by the 21 679 splenial in life. The ventral margin of the dentary slopes gradually upwards, partially 22 23 680 obscured by the repair medium, and its depth below the dental lamina zone diminishes from 24 25 681 some 40 mm below teeth 1-3, to 34 mm below teeth 0-11, and presumably further 26 682 diminishing in depth more posteriorly. There is a large opening, measuring 32 x 18 mm, 27 28 683 located below teeth 7-9 on this medial portion of the dentary, but it is uncertain whether this 29 30 684 is a real structure or a result of enthusiastic preparation work. It does not match any such 31 685 opening in other basal tetrapods. 32 33 686 Above this medial dentary plate is a deep dental lamina zone (Fig. 7B, d.l.), varying 34 35 687 from 20 mm deep below tooth 7 to 10 mm deep below tooth 15. This zone lies above a clearly 36 688 demarcated rounded margin of the dentary bone, and the bone texture switches from relatively 37 38 689 smooth and longitudinally striated below the demarcation to irregular and vertically striated in 39 40 690 the dental lamina zone. Further, this zone contains many circular-topped erosion hollows 41 691 where teeth were presumably in the process of being implanted into the dentary bone from the 42 43 692 soft-tissue dental lamina. Three such replacement teeth are in place, in order of advancement 44 45 693 of eruption, beneath marginal teeth 17 and 14, and tooth 11, which has expelled its precursor 46 694 and is moving up into place in the marginal tooth row. The equal spacing (three teeth apart) 47 48 695 could suggest a Zahnreihe, a wave of tooth replacement running from back to front of the 49 50 696 tooth row (DeMar 1972). There is a trace of a replacement tooth in a small pit beneath tooth 51 697 1. Further, there are irregular erosion pits in the dental lamina beneath teeth 15, 12, 8-10, 7, 52 53 698 and 5. The status of teeth 3-4 is hard to determine: tooth 4 is complete, but has been exposed, 54 55 699 broken off, and re-inserted into the jaw bone partially reversed by a preparator, whereas the 56 700 position of tooth 3 is marked by a deep depression in the jaw margin, possibly from original 57 58 701 jaw damage or from over-preparation. 59 60 Zoological Journal of the Linnean Society Page 22 of 85

22 1 2 3 702 There is no sign of a coronoid bone, and the splenial is apparently entirely missing, 4 5 703 leaving the ventral margin of the dentary exposed as a wafer-thin bone plate, and showing the 6 704 anterior process of the angular in medial view. 7 8 705 The sutures among the post-dentary elements are not clear. The angular forms most of 9 10 706 the lower margin of the jaw, being presumably at least 250 mm long as seen in medial view 11 707 (Fig. 7B, an.). The anterior tip is broken off, so it would have been longer. The lateral portion 12 13 708 of the angular lies beneath the dentary, in a longitudinal facet on the medial side of the lateral 14 15 709 plate of the dentary about 11 mm deep. The ventral margin of the angular is narrow, ranging 16 710 from 10-20 mm in medio-lateral width, but the medial side of the hemimandible suggests 17 18 711 there may have beenFor some crushing Review and a partial collapse Only of the Meckelian fossa. On the 19 20 712 medial face, the dorsal contacts of the angular with the prearticular and articular cannot be 21 713 seen with certainty, but some possible indications are shown (Fig. 7A, sa?). In lateral view 22 23 714 (Fig. 7A, ma.f.), the ventral margin of the mandibular fenestra at least seems genuine, and the 24 25 715 dorsal extent might be also, or perhaps slightly enlarged. In any case, the mandibular fenestra 26 716 appears to measure 32 x 16 mm. The contact between angular and surangular seems to begin 27 28 717 just above and behind the mandibular foramen, and then it becomes obscure posteriorly. The 29 30 718 angular boss, a substantial vertical extension of the bone seen in most pareiasaurs, is at best 31 719 only modest here, represented by a slight downwards expansion of the posterior portion of the 32 33 720 mandible when the dentary tooth row is held horizontal. Gao (1983: pl. 1, figs. 3,4) identified 34 35 721 IVPP V6722-3 as the angular boss, and suggested the structure lay far forward, essentially 36 722 below its current anterior termination (Gao 1983: fig. 1). However, this very anterior location 37 38 723 is impossible as that portion of the angular was demonstrably covered by the splenial in life. 39 40 724 Present evidence suggests that Shihtienfenia had only a modest ventral angular boss, and 41 725 IVPP V6722-3 is identified here as a possible jugal (see above). 42 43 726 The surangular is presumably bordered by the dentary anteriorly, and the contact is 44 45 727 lost in the zone of repair medium, the angular ventrally, as noted, and it sweeps round the 46 728 pediment of the articular facet of the jaw. The prearticular is similarly of uncertain extent 47 48 729 (Fig. 7B, pa?), its anterior contact with the dentary obscured beneath repair medium, and its 49 50 730 ventral contact with the angular only seen incompletely. Finally, the articular is presumably 51 731 largely restricted to the articular facet, which is 70 mm in antero-posterior length and 50 mm 52 53 732 in medio-lateral width. The articular face (Fig. 7C, ar) consists of an elongate lateral portion 54 55 733 that curves around the medial face, and descends substantially ventrally in the posterior 56 734 portion. The smaller medial portion of the articular facet is 36 mm in antero-posterior length 57 58 59 60 Page 23 of 85 Zoological Journal of the Linnean Society

23 1 2 o 3 735 and 23 mm in medio-lateral width, and it sits at an angle of 60 above horizontal, facing 4 5 736 mainly medially. 6 737 7 8 738 Splenials - IVPP V6772-2 consists of much of the two splenials of a pareiasaur (Fig. 7D, E), 9 10 739 and the size is about right for these to match IVPP V6772-1, which lacks the splenials. 11 740 Indeed, the proportions of the missing splenial in IVPP V6772-1, the curvature of the jaw 12 13 741 line, and the shape of the ventral margins of the dentary all make a very good match to IVPP 14 15 742 V6772-2. However, the preservation is rather different, the latter specimen being somewhat 16 743 ‘rougher’ in appearance, and bearing patches of a deeper red colour, whereas the 17 18 744 corresponding portionsFor of IVPP Review V6772-1 are preserved Onlywith a better bone surface texture and 19 20 745 the predominant colour is grey. However, the postdentary portion of IVPP V6772-1 is similar 21 746 in texture and colour to IVPP V6772-2, so the two may have been disarticulated before death, 22 23 747 and they might conceivably have come from the same individual. As preserved, the left 24 25 748 splenial is 205 mm long, measured round the curve, and the right splenial 230 mm long. The 26 749 symphysis is thick, and measures 48 mm antero-posteriorly at the midline, compared to 28 27 28 750 mm at the narrowest point of the anterior portion. This midline thickening is seen also in other 29 30 751 pareiasaurs, such as Pareiasuchus (Lee et al. 1997: fig. 7C). There is a distinct channel 31 752 running the entire length of each splenial, beginning as a depression that is open posteriorly at 32 33 753 the front, and then the medial thin wall rises some 40 mm behind the symphysis to a height of 34 35 754 25 mm, where the wall bounds the base of the medial flange of the dentary. The lateral wall of 36 755 the splenial longitudinal groove begins low and broad, and rises to a height of 20 mm above 37 38 756 the base of the groove. These medial and lateral splenial walls are incomplete, but would have 39 40 757 bounded the anterior part of the Meckelian fossa (Fig. 7C, me.f.). The base of the canal is 41 758 somewhat irregular, and it is hard to identify a step where the anterior process of the angular 42 43 759 inserted. In ventral view (Fig. 7E), the splenial expands to an approximate medio-lateral 44 45 760 breadth of 32 mm on the left and 35 mm on the right, perhaps indicating the true original 46 761 breadth of the lower portion of each hemimandible, and perhaps confirming the suggestion 47 48 762 above that IVPP V6722-1 might have been gently medio-laterally compressed. 49 50 763 The external surface of both specimens is sculpted with a subtle, and low pattern of 51 764 small bosses, 1-2 mm in diameter, and thin ridges, each less than 1 mm wide. If anything, the 52 53 765 ventral face of the splenials seem more sculpted than the dentary and post-dentary elements in 54 55 766 IVPP V6722-1. 56 767 57 58 59 60 Zoological Journal of the Linnean Society Page 24 of 85

24 1 2 3 768 Right dentary - The unnumbered specimen, in a box of uncatalogued fragments and scraps 4 5 769 of bone associated with IVPP V6722, is a roughly prepared anterior right hemimandible, 6 770 exactly matching IVPP 6722-1, and fitting neatly on the midline symphysis. The specimen 7 8 771 (Fig. 8A, B) carries 17 teeth, some complete and others rather broken, and it shows the dental 9 10 772 lamina and the medial face of the dentary that roofs the anterior portion of the Meckelian 11 773 cartilage. The lateral surface is rough and poorly preserved, and it terminates above the point 12 13 774 at which it would have contacted the splenial. 14 15 775 16 776 Dentition - The teeth of IVPP V6772-1 (Figs. 7A–C, 8C, D) individually have cylindrical 17 18 777 roots, nearly perfectlyFor circular inReview cross section, measuring Only 7-9 mm across (Table 1). These 19 20 778 expand into the slightly flattened, rhomb-shaped crown, which is typically 14-20 mm dorso- 21 779 ventrally high and 11-12 mm antero-posteriorly wide. With 19 teeth in 200 mm, this means 22 23 780 the crowns overlap slightly, the anterior margin of each tooth at its widest part being located 24 25 781 medially of the posterior margin of the tooth in front. The teeth individually vary in length 26 782 and breadth (Table 1), but there is no sign of a regular pattern of increasing or diminishing 27 28 783 size from front to back – tooth size is difficult to measure because many teeth have partly 29 30 784 damaged edges. The teeth are curved convex-laterally from ventral root to dorsal crown. The 31 785 dorsal margin of the dentigerous portion of the maxilla is little more than 10 mm thick medio- 32 33 786 laterally, and so the teeth form the bulk of this element, being separated by thin inserts of 34 35 787 bone. The root slopes dorso-laterally, and emerges at the very lateral edge of the dentary with 36 788 which the lateral (lingual) face of the tooth crown is more or less parallel, each rising near- 37 38 789 vertically. In medial (labial) view (Fig. 8D), the tooth crowns are somewhat concave 39 40 790 medially. Each crown is an asymmetrical rhomb, with the shorter edges ventrally, and the 41 791 longer edges dorsally, above a marked cingulum (Fig. 8E, ci). Above the cingulum, in fully 42 43 792 erupted teeth, a midline bulge ascends the medial face of the crown, demarcated by two ridges 44 45 793 (Fig. 8E, ri) that curve from the cingulum to the denticles on either side of the middle two 46 794 denticles at the dorsalmost point of the tooth. 47 48 795 A series of seven or eight well-marked, pointed denticles or cusps extends along each 49 50 796 margin of the tooth crown, giving a total of 13-17 on each tooth crown (Fig. 8C–E; Table 1). 51 797 Unlike the more longitudinally oriented cusps in the maxillary teeth of Sanchuansaurus (see 52 53 798 above), these cusps point more to the sides, in other words anteriorly and posteriorly, as seen 54 55 799 also in species of Pareiasuchus and Scutosaurus (Lee et al. 1997: 325). 56 800 Despite previous assertions about Huanghesaurus (coded as ‘Shansisaurus’ by Lee 57 58 801 1997: 231; Jalil & Janvier 2005: 192), this taxon shows a distinct cingulum (Fig. 8E, ci), 59 60 Page 25 of 85 Zoological Journal of the Linnean Society

25 1 2 3 802 demarcating the somewhat hollowed, or spoon-shaped labial crown face. The cingulum 4 5 803 traverses the entire width of the tooth, and bears two or three denticles on either side of a 6 804 substantial midline lingual ridge that bears two distinct longitudinal ridges close to the 7 8 805 midline, and divides the crown 9 10 806 11 807 Comparison - The lower jaw specimens allow coding of several phylogenetically informative 12 13 808 characters: the splenial forms the ventral portion of the mandibular symphysis (Lee 1997, 14 15 809 character 51; Tsuji 2013, character 46); the ventral surface of the angular is smooth and with 16 810 no boss (Lee 1997, character 52; Tsuji 2013, character 47); there is a small dorsal projection 17 18 811 on the retroarticularFor process (Lee Review 1997, character 54; Tsuji Only 2013, character 48); there is no 19 20 812 lateral shelf on the articular (Tsuji 2013, character 49); the teeth are labiolingually 21 813 compressed, leaf-shaped, and with small denticles on the tooth crown (Lee 1997, character 22 23 814 58; Tsuji 2013, character 52); cusps are regularly spaced along the tooth crown (Lee 1997, 24 25 815 character 61; Tsuji 2013, character 53); there are more than 11 marginal cusps on each 26 816 dentary tooth (Lee 1997, character 60; Tsuji 2013, character 55); the mandibular teeth show a 27 28 817 distinct, triangular ridge, narrowing towards the crown of the tooth (Lee 1997, character 63; 29 30 818 Tsuji 2013, character 56); there is a cingulum present, with small cuspules (Lee 1997, 31 819 character 64; Tsuji 2013, character 57); and there is no caniniform region in the tooth row 32 33 820 (Tsuji 2013, character 120). 34 35 821 36 822 37 38 823 AXIAL SKELETON 39 40 824 41 825 INTRODUCTION 42 43 826 44 45 827 The original materials of Shihtienfenia included ‘about 20 vertebrae’ in the holotype (IVPP 46 828 V2717) and ‘11 more or less well preserved dorsal vertebrae and some fragments of the same’ 47 48 829 in the paratype (IVPP V2718, specimen now missing). Young & Yeh (1963: 207-208) 49 50 830 described four isolated possible cervical vertebrae, four isolated anterior dorsals, a block 51 831 containing four posterior dorsals, perhaps numbers 16-20, near to, but not quite contacting the 52 53 832 sacrum, a block of five sacral vertebrae, and two isolated caudal vertebrae, one of which 54 55 833 belongs to IVPP V2717. The specimens are somewhat distorted, and some are incomplete, 56 834 but the articulated series, the appropriate sizes of all materials (Table 2), and the apparently 57 58 59 60 Zoological Journal of the Linnean Society Page 26 of 85

26 1 2 3 835 close proximity of all specimens, is strong evidence that the holotype (IVPP V2717) is a 4 5 836 single specimen. 6 837 The Huanghesaurus holotype includes 13 vertebrae (IVPP V6722-4 to 16) and six 7 8 838 partial ribs (IVPP V6722-17 to 22) and, as ever, these are hard to assign to their exact 9 10 839 locations in the vertebral column. Pareiasaurs typically have 17-21 presacral vertebrae, the 11 840 lower numbers being found in more basal taxa (Lee 1997). It is likely the 13 vertebrae of 12 13 841 Huanghesaurus come from a single individual, as they were all found together in one spot 14 15 842 (Gao 1983), they appear to match in overall dimensions, and they show subtly changing 16 843 morphology from one to the next. Clearly, several vertebrae are missing, and the present 17 18 844 materials do not permitFor any estimate Review of total presacral vertebralOnly numbers (Lee 1997, character 19 20 845 67). 21 846 The first vertebrae (IVPP V6722-4 to 7) appear to form an articulating sequence (Gao 22 23 847 1983: fig. 2, pl. 1, fig. 6), and they are quite different in morphology from the others (IVPP 24 25 848 V6722-8 to 16). The first four are identified as posterior cervical vertebrae on the basis of 26 849 three characters: the parapophysis and diapophysis are entirely distinct from each other, the 27 28 850 transverse processes are located far anteriorly (Jalil & Janvier 2005: 76), and the neural spine, 29 30 851 most unusually, slopes forwards. Of the further two criteria given by Jalil & Janvier (2005: 31 852 76), we see some compression of the centra, but not ‘the very pronounced compression’ they 32 33 853 note, nor do the specimens bear the longitudinal, median ridge on the ventral surface seen in 34 35 854 the Moroccan pareiasaur. The other vertebrae (IVPP V6722-8 to 16) are identified as dorsals, 36 855 and probably posterior dorsals, on the basis of their short centra, fused rib attachments located 37 38 856 less anteriorly, near-vertical neural spine, and the massive transverse processes, resembling in 39 40 857 many ways the middle to posterior dorsals of the Moroccan pareiasaur (Jalil & Janvier 2005, 41 858 figs. 32, 33). 42 43 859 Few phylogenetically informative characters of the axial skeleton can be coded with 44 45 860 confidence. In that all putative presacral vertebrae of both Shihtienfenia and Huanghesaurus 46 861 show transverse processes with rib attachments, there is no evidence that either specimen had 47 48 862 ribless lumbar vertebrae (Lee 1997, character 68; Tsuji 2013, character 62). Shihtienfenia has 49 50 863 five sacral vertebrae (Lee 1997, character 93; Tsuji 2013, character 63). Further, Shihtienfenia 51 864 shows the primitive amniote morphology of the second and third sacral ribs showing only 52 53 865 slight dorsoventral compression (Lee 1997, character 94; Tsuji 2013, character 84). 54 55 866 56 867 POSTERIOR CERVICAL VERTEBRAE 57 58 868 59 60 Page 27 of 85 Zoological Journal of the Linnean Society

27 1 2 3 869 Young & Yeh (1963:207) refer to ‘four isolated neck vertebrae’ of Shihtienfenia, of which 4 5 870 three are incomplete centra, and cannot be further described, and the fourth is more complete. 6 871 It presents an unusual shape, showing the somewhat crushed and incomplete centrum and the 7 8 872 right-hand lateral portion of the vertebra. The centrum (IVPP V2717) is tall and narrow 9 10 873 (Table 2) and the paired axially oriented bases of the neural arch (Fig. 9A, n.a.) are clear, 11 874 spaced some 30 mm apart. The lateral portion of the vertebra includes the prezygapophysis, 12 13 875 projected far laterally, up to 140 mm from the midline, and with an articular facet 80 mm 14 15 876 mediolaterally long and 35 mm anteroposteriorly deep. Beneath the prezygapophysis, a wall 16 877 of bone descends vertically, and expands forward into the flared transverse process (Fig. 9A, 17 18 878 t.p.) with a facet someFor 110 mm Reviewlong at most. This vertical Only lamina beneath the 19 20 879 prezygapophyseal articular facet also flares backwards as a separate process, but the detail is 21 880 unclear because the posterior part of the vertebra is incomplete. Such broad posterior cervical 22 23 881 vertebrae, with a wall-like flange connecting the laterally projected prezygapophysis and 24 25 882 transverse process, are typical of pareiasaurs (e.g. Jalil & Janvier 2005; Tsuji & Müller 2008; 26 883 Tsuji 2013). 27 28 884 The four posterior cervicals of Huanghesaurus are two rather incomplete specimens, 29 30 885 consisting of centrum and base of the neural arch only (IVPP V6722-4 and 5) and two rather 31 886 more complete specimens (IVPP V6722-6 and 7). The description is based primarily on the 32 33 887 latter two specimens, with comparative remarks for the others (Table 3). In these, the centrum 34 35 888 is more or less square when viewed laterally (Fig. 9B), with a slightly emarginated ventral 36 889 margin, and broadly overturned articular faces. The mid-central pinching is more marked 37 38 890 when viewed ventrally, but there is no clear mid-ventral ridge. The articular faces are roughly 39 40 891 circular in shape, with a slight ventral prolongation associated with the ventral lateral 41 892 pinching of the centrum. Both faces are deeply amphicoelous, with a deep, centrally located 42 43 893 pit, which is much deeper on the posterior than the anterior face. In lateral view, the 44 45 894 diapophysis and parapophysis are pronounced (Fig. 9B, dp., pp.), each standing well proud of 46 895 the centrum surface, and located about midway between the two articular ends. These two rib 47 48 896 facets are of about equal size in three of these vertebrae, each measuring about 20 x 33 mm, 49 50 897 but the diapophysis is somewhat narrower in IVPP V6722-4, measuring 14 x 32 mm. They 51 898 are oval, and each slopes back and down. Their diagonal arrangement means that the 52 53 899 diapophysis is set slightly more posteriorly, the parapophysis more anteriorly, implying that 54 55 900 the ribs canted substantially backwards. 56 901 The contact between centrum and neural arch is hard to detect, partly because it may 57 58 902 have been fused in life, but also because of the rather coarse preservation. Presumably the line 59 60 Zoological Journal of the Linnean Society Page 28 of 85

28 1 2 3 903 of contact ran along the base of the neural canal, and then between diapophysis (on the neural 4 5 904 arch) and parapophysis (on the centrum). The base of the neural arch surrounds a narrow 6 905 neural canal, 27 mm wide and 14 mm high, and beneath the rather modestly sized 7 8 906 prezygapophyses, the whole neural arch is only 50 mm wide, just over half the width of the 9 10 907 centrum. The prezygapophyses, best seen in IVPP V6722-4 (Fig. 9B, prz.), are set back and 11 908 do not project in front of the line of the anterior articular face of the centrum. The articular 12 13 909 faces are oval, measuring 45 x 24 mm, and with the long axis oriented nearly parasagittally. 14 o 15 910 They are tilted up at about 35 from medial to lateral. The postzygapophyses, best seen in 16 911 IVPP V6722-6 (Fig. 9B, poz.), have an articular face that measures 50 x 28 mm, with the long 17 18 912 axis oriented parasagittally.For The Review postzygapophyses are setOnly far back, and project entirely 19 20 913 beyond the posterior margin of the centrum. 21 914 The neural spine is most unusual, sloping substantially forwards (Fig. 9B, n.sp.). Its 22 23 915 base is set well back, emerging above the proximal portions of the postzygapophyses. It then 24 25 916 slopes forwards, with the posterior margin beginning above the posterior margin of the 26 917 centrum, and running upwards and forwards, with a gentle concave curve, and the anterior 27 28 918 margin more or less straight. The neural spine is 85 mm long on the anterior margin, and 80 29 30 919 mm along the posterior margin from the dorsal root of the postzygapophysis to the tip. The 31 920 spine is somewhat oval in cross section, with modest anterior and posterior midline ridges, 32 33 921 The distal tip of the spine broadens laterally, with a maximum width of 50 mm, and 34 35 922 maximum antero-posterior depth of 24 mm. The distal end bears two broad bosses, one on 36 923 each side, forming a symmetrical, C-shaped curved head in dorsal view, with the concave 37 38 924 face anteriorly, and the convex surface posteriorly. 39 40 925 41 926 ANTERIOR DORSAL VERTEBRAE 42 43 927 44 45 928 Three incomplete and laterally compressed vertebrae of the holotype of Shihtienfenia (IVPP 46 929 V2717) are identified as anterior dorsals (Young & Yeh 1963: 207-208, fig. 5). The centra are 47 48 930 tall and narrow (Table 2), doubtless much exaggerated by lateral crushing. The articular faces 49 50 931 of the centra show deep central excavations, and broadly overturned lips. The anterior face of 51 932 the vertebra identified as 11 (Fig. 9C) shows a concave articular face of the centrum, 52 53 933 surmounted by distorted transverse processes, one pointing up and the other down, and the 54 55 934 neural spine twisted round to the side. On the left sides of vertebrae identified as 11 and 12 56 935 (Fig. 9D) an extensive bone lamina descends on the lateral face of the centrum, providing the 57 58 936 diapophyseal articulation at just above mid-height of the centrum, and the parapophyseal 59 60 Page 29 of 85 Zoological Journal of the Linnean Society

29 1 2 3 937 articulation 60 mm or so higher on the transverse process, although this portion is not 4 5 938 preserved. Vertebra 13 (Young & Yeh 1963: fig. 5) is incomplete and retains little to describe 6 939 (Fig. 9E), whereas vertebra ?14 is more complete, with the anterior view (Fig. 9F) showing 7 8 940 the massive zygapophyses, a circular neural canal measuring 25 x 27 mm, and the base of the 9 10 941 anteriorly located neural spine. The hypantrum noted by Young & Yeh (1963: fig. 5, top 11 942 right) cannot be seen. 12 13 943 A single vertebra that formed part of the holotype of Shansisaurus xuecunensis 14 15 944 (Cheng 1980: fig. 18; CAGS V301) appears to be a partial anterior or middle dorsal. The 16 945 anterior articular face is slightly taller than wide and deeply excavated. It is surmounted by a 17 18 946 tiny neural canal, andFor expands substantiallyReview laterally in theOnly preserved right-hand side, which 19 20 947 shows a large prezygapophysis projected up to 85 mm from the midline. Beneath it, and 21 948 projecting only slightly less far is the transverse process, apparently with a single 22 23 949 diapophyseal head. 24 25 950 26 951 POSTERIOR DORSAL VERTEBRAE 27 28 952 29 30 953 The five articulated posterior dorsal vertebrae of Shihtienfenia (Fig. 10A–C) are all 31 954 incomplete, lacking the neural spine in all cases, the prezygapophyses in numbers 16, 17 and 32 33 955 20, the postzygapophyses in numbers 16 and 20, and much of the posterior part of the 34 35 956 centrum in 20. Note that the numbering comes from Young and Yeh (1963, fig. 2), based on 36 957 context of discovery. These vertebrae all share similar dimensions, so far as can be measured 37 38 958 (Table 2). The centrum is narrow, taller than broad, with deeply concave sides. The articular 39 40 959 faces are deeply concave, with the deepest portion penetrating in the centre. The marginal lips 41 960 of the articular faces are substantially turned over, and ventrally, these overturned portions of 42 43 961 the articular faces extend considerably. In ventral view (Fig. 10C), where the vertebrae meet, 44 45 962 the anterior and posterior overturned articular faces form a substantial diamond-shaped facet 46 963 between each pair of vertebrae, some 60 mm measured axially. Thus, the ventral portion of 47 48 964 each centrum, which typically measures 90 mm long (Table 2; Fig. 10C), is composed of 49 50 965 three equal-length portions, the anterior articular facet and the posterior articular facet, 51 966 separated by only 30 mm of ventral centrum which forms a narrow ridge between. This 52 53 967 extreme articular foldover and ventral facet is not seen in dorsal vertebrae of Huanghesaurus. 54 55 968 In all five vertebrae, the rib attachment is projected on a short transverse process (Fig. 56 969 10A, B, t.p.) which projects laterally little more than the prezygapophysis. The rib facet, 57 58 970 representing the fused diapophysis and parapophysis, is broad and rounded, not as elongate as 59 60 Zoological Journal of the Linnean Society Page 30 of 85

30 1 2 o 3 971 in Huanghesaurus, with the long axis, 50-55 mm long, slanting at 45 from posterodorsal to 4 5 972 anteroventral, and 30 mm measured orthogonally. In lateral view (Fig. 10B, prez., poz.), the 6 973 prezygapophyses project far forward of the anterior margin of the centrum, and this is 7 8 974 matched by the anterior location of the neural spine and postzygapophyses which, although 9 10 975 huge (the postzygapophyseal facet of presacral 19 measures 95 x 55 mm), do not extend 11 976 behind the posterior articular face of the centrum. 12 13 977 The posterior dorsal vertebrae of Huanghesaurus (Table 3) include several more or 14 15 978 less complete specimens (IVPP V6772-8, 12, 13, 15), and others (IVPP V6772-9, 11, 14) 16 979 missing most of the neural arch and transverse processes, and one lacking the centrum (IVPP 17 18 980 V6772-16). The mostFor complete Review example (IVPP V6722-15 Only) is a massive vertebra, with a short 19 20 981 centrum, and massive zygapophyses and transverse processes (Fig. 10D–F). In lateral view 21 982 (Fig. 10E), the centrum is substantially constricted from side to side, reduced to half the width 22 23 983 of the articular faces, but the ventral emargination, although pronounced, is less substantial. 24 25 984 The articular faces lie roughly at the same level with no vertical offset, but the centrum is 26 985 distorted moderately laterally. The articular faces are similar in shape, being somewhat 27 28 986 circular, but wider than high, and the anterior face is slightly larger than the posterior (Table 29 30 987 3). The centrum is deeply amphicoelous, with a narrow, but very deep hollow in the centre of 31 988 each articular face (Fig. 10D, F). 32 33 989 The anterior view of the neural arch consists of massive, flat lateral laminae on either 34 35 990 side of a tiny neural canal (Fig. 10D, n.c.), about 18 mm wide and tall (it is up to 25 mm wide 36 991 in other dorsal vertebrae). These lateral laminae rise to the base of the prezygapophyses, 37 38 992 which are missing, but presumably had articular faces tilting down and back, to judge from 39 40 993 the postzygapophyses. The transverse process sprouts from immediately below the base of the 41 994 prezygapophysis (Fig. 10D, t.p., prz.), and runs up and slightly backwards, terminating in a 42 o 43 995 broad distal tip. The rib facet, clear on the right-hand side, is a single structure, oriented at 45 44 45 996 anteroventrally, and shaped like an extended, pinched oval, some 80 mm long, 25 mm deep in 46 997 the anterior part and 23 mm in the posterior, and narrowing to 12 mm wide in the middle (Fig. 47 48 998 10E, r.f.). The articular face of this facet is concave. In other dorsals (e.g. IVPP V6722-8), the 49 50 999 transverse process is at most 50 mm wide antero-posteriorly. The lamina beneath the 51 1000 transverse process runs from its distal end to the rib facet located anterodorsally on the side of 52 53 1001 the centrum; this lamina is from 15 to 25 mm thick anteroposteriorly. In posterior view (Fig. 54 55 1002 10F), the transverse process proper stands distinctly apart from the lamina beneath, the 56 1003 division being marked by a substantial depression in the whole ventral part of the lamina. The 57 58 59 60 Page 31 of 85 Zoological Journal of the Linnean Society

31 1 2 3 1004 depth of the lamina varies from substantial in IVPP V6722-8 to more shallow in IVPP 4 5 1005 V6722-15. 6 1006 The postzygapophyses are massive, each extending some 120 mm from the midline, 7 8 1007 and so similar in length to the transverse processes below. Each postzygapophysis (Fig. 10D– 9 10 1008 F, poz.) extends more or less horizontally from the midline, and the articular face is canted at 11 1009 an angle of some 20o, facing ventro-anteriorly. The facet is not flat, but curved from front to 12 13 1010 back and from distally to proximally, and it sweeps down to meet the dorsal margin of the 14 15 1011 transverse process, in posterior view (Fig. 10F). There is a deep space between the 16 1012 postzygapophyses in the midline, and the tiny (17 x 17 mm) neural canal lies some distance 17 18 1013 below, and partly behindFor the raised Review margin of the posterior Only articular face. 19 20 1014 The neural spine stands nearly vertical, unlike that of the cervicals, but it is similarly 21 1015 massive and carries a similar expanded double-bossed distal end. The neural spine emerges 22 23 1016 from the top of the massive postzygapophyses, and because of the way they sweep 24 25 1017 downwards to the upper margin of the transverse process, and because the shortening of the 26 1018 whole vertebra, a ∧-shaped cavity is formed beneath the base of the neural spine when seen in 27 28 1019 anterior view (Fig. 10D). The neural spine is 105 mm tall, broadening from a minimum width 29 30 1020 of 30 mm to 52 mm at the massively expanded and heavy dorsal tip. In life, these massive 31 1021 boss-like neural spines probably articulated with each other, forming a basis for some of the 32 33 1022 massive dorsal armour, as shown by Seeley (1892: pl. 17) for Pareiasaurus. The shaft of the 34 35 1023 neural spine is deeper antero-posteriorly than wide laterally, and it has a somewhat triangular 36 1024 anterior face, coming to a ridge that extends in the midline from base to tip of the neural 37 38 1025 spine. In posterior view (Fig. 10F), the neural spine bears a midline ridge proximally, but this 39 40 1026 splits into two narrow ridges that diverge dorsally. The distal end of the neural spine in 41 1027 posterior view carries a broad boss at each side, and is slightly hollowed between; the 42 43 1028 diverging ridges each run to the base of the lateral distal bosses. 44 45 1029 Specimen IVPP V6722-15 is illustrated by Gao (1983: fig. 3), but the posterior view is 46 1030 labelled as ‘anterior’, and the details of the vertebra are slightly stylised, with an inaccurate 47 48 1031 rendition of the posterior depression beneath the transverse process. The ‘figure of eight’ rib 49 50 1032 facet terminating the transverse process seen in this specimen (Fig. 10E, r.f.) is very similar to 51 1033 that shown by the Pareiasauria gen. et sp. indet., from the Upper Permian of Morocco (Jalil & 52 53 1034 Janvier 2005: 80). 54 55 1035 Accessory articulations between dorsal vertebrae, the hypantrum and hyposphene, 56 1036 were noted in dorsal vertebrae of Shihtienfenia by Young & Yeh 1963: 207, fig. 5) and in 57 58 1037 dorsal vertebrae of Huanghesaurus by Gao (1983: 196), but these identifications seem to be 59 60 Zoological Journal of the Linnean Society Page 32 of 85

32 1 2 3 1038 incorrect. The structures labelled by Young & Yeh (1963: fig. 5) are sketchy and hard to 4 5 1039 match with the specimens. Young & Yeh (1963: 207) describe these structures as follows: ‘In 6 1040 the anterior view the “hypantrum” is weakly indicated. Between it and the neural canal there 7 8 1041 is a weakly developed pyramid-like development which [is] not found in any of the related 9 10 1042 forms. This structure is, however, missing in the fourth isolated vertebra.” Further, in 11 1043 describing Huanghesaurus, Gao (1983: 196) reports that “The hypantrum and hyposphene are 12 13 1044 all pronounced” in the dorsal vertebrae, although they are not marked in the figures or further 14 15 1045 described. In Shihtienfenia, these appear to be singular midline structures, and little more than 16 1046 the hollow between the base of the flaring postzygapophyses (‘hyposphene’) and an irregular 17 18 1047 single, midline projectionFor above Review the neural canal (‘hypantrum’). Only In Huanghesaurus, for 19 20 1048 example the dorsal vertebrae IVPP V6722-8, 10 and 15 show a slight expansion of the lamina 21 1049 below the location of the (missing) prezygapophyses, on either side and close to the midline, 22 23 1050 just above the neural canal (Fig. 10D), and these angular structures are seen also in IVPP 24 25 1051 V6722-10, but these do not show any facet, and there is no matching structure beneath the 26 1052 postzygapophyses. Further, these putative facets are tiny when compared to the rather 27 28 1053 substantial zygapophyses, and are presumably just small projections that perhaps carried 29 30 1054 intervertebral muscles or ligaments and no more. 31 1055 Such additional articulations are well known in trunk vertebrae of sauropodomorph 32 33 1056 dinosaurs (Apesteguia 2005) and theropods, and might be a saurischian synapomorphy, as 34 35 1057 they are absent in ornithischians (Gauthier 1986; Langer & Benton 2006). In addition, these 36 1058 accessory articulations have been identified in some basal archosaurs (notably, large 37 38 1059 rauisuchids), basal sauropterygians (Rieppel 1994), placodonts (Rieppel 2000), and diadectids 39 40 1060 (KIssel & Lehman 2002). In these taxa, the hyposphenes and hypantra are paired structures 41 1061 lying between, and slightly below the zygapophyses, and with definite facets for contact when 42 43 1062 the vertebrae are articulated. The hypantra and hyposphenes described in the Chinese 44 45 1063 pareiasaurs appear to be illusory. 46 1064 47 48 1065 SACRAL AND CAUDAL VERTEBRAE 49 50 1066 51 1067 The only sacrum so far reported is a substantial specimen in the type of Shihtienfenia (IVPP 52 53 1068 V2717) showing five vertebrae in articulation (Fig. 11). Young & Yeh (1963: 208) note that 54 55 1069 the first of the series is broken, and they speculate that there might have been a further sacral 56 1070 in front, making six in all. This is a high figure, in view of the fact that pareiasaurs generally 57 58 1071 had four or five sacral vertebrae; Lee (1995, 1997: 239-240) prefers to regard the putative 59 60 Page 33 of 85 Zoological Journal of the Linnean Society

33 1 2 3 1072 sixth sacral of Shihtienfenia as the first caudal. These statements may sound confusing, in that 4 5 1073 the first authors refer to an additional anterior sacral, and Lee refers to a putative additional 6 1074 posterior one. Young & Yeh (1963) are right that the first sacral is represented by a 7 8 1075 substantial sacral rib on the left side, but Lee (1995, 1997) is correct that the posteriormost of 9 10 1076 the six vertebrae in the block is likely the anteriomost caudal. 11 1077 The block of six vertebrae is fused, and the centra of vertebrae 2-5 form a dorsally 12 13 1078 convex curve, running smoothly from one to the next (Fig. 11A; Table 2). Despite distortion 14 15 1079 in many specimens, this arch seems so smooth and regular that it may be original. As noted, 16 1080 the first vertebra in the series is incomplete, missing most of the centrum. The 17 18 1081 postzygapophyses Forare present, butReview the neural spine is missing. Only 19 20 1082 The divisions between centra 2 to 4 are hard to make out because of the close 21 1083 association of these vertebrae, and the absence of extreme broadening or overturn at the 22 23 1084 articular faces. Sacral 5 shows a more spool-shaped centrum, with slightly expanded articular 24 25 1085 ends, and this is more marked in caudal 1. Sacral centra 2-4 then show little lateral narrowing, 26 1086 and no sign of a ventral ridge (Fig. 11D). Sacral 5 and caudal 1 do show some lateral 27 28 1087 pinching, but the ventral view shows no sign of a narrow ridge. All centra are of roughly 29 30 1088 equal length (Table 2), but observations on the articular faces and dorsal regions of the centra 31 1089 are impossible because of the way the specimens are so closely associated. The anterior face 32 33 1090 of sacral centrum 1 is partly obscured, but the posterior face of caudal centrum 1 appears 34 35 1091 deeply excavated. 36 1092 In the more complete sacrals 2-4, the neural spine is near vertical, and located well 37 38 1093 forward (Fig. 11A, B, n.sp.), as in the dorsals. The distal tips of the sacral neural spines are 39 40 1094 missing, but the remainder of the three spines is a laterally compressed rod, 55 mm long 41 1095 anteroposteriorly at the base and 45 mm at the distal end, as preserved, and from 25 mm wide 42 43 1096 mediolaterally at the base and 12 mm distally. The neural spine flares ventrally into the 44 45 1097 postzygapophyses: these diminish substantially from a length of 80 mm in sacral 1, to 45 mm 46 1098 in sacrals 2 and 3, and 40 mm in sacral 4. At the same time they become narrower, and 47 48 1099 directed much more dorsally than in the dorsal vertebrae, where they are massive laterally 49 50 1100 directed elements. The angle of the midline of the postzygapophyses in dorsal vertebrae was 51 1101 some 10o posterior to lateral, whereas these sacral postzygapophyses are oriented at some 60o 52 53 1102 posterior to lateral. The prezygapophyses are less clear, but can be seen firmly adhering below 54 55 1103 the narrow postzygapophyses of sacrals 3 and 4 (Fig. 11A–C, poz., prz.). Presumably the 56 1104 substantial fusion of the sacral centra and ribs reduces the need for strengthening of the 57 58 1105 vertebral column by substantial zygapophyses. 59 60 Zoological Journal of the Linnean Society Page 34 of 85

34 1 2 3 1106 The lower neural arch expands anterior to the postzygapophysis to form a short 4 5 1107 transverse process that extends nearly vertically, but slightly posteriorly ventrally over the 6 1108 upper lateral face of the centrum. Sacral ribs are seen on both sides, but the first and second 7 8 1109 are best on the left. The first sacral rib appears largest, and it runs diagonally backwards from 9 10 1110 a massive near-vertical medial attachment to the neural arch of sacral vertebra 1 (Fig. 11A, D, 11 1111 s.r.1). The first sacral rib on the left measures 180 mm long on its dorsal margin, and tapers 12 13 1112 from a dorsoventral height of 115 mm proximally to 65 mm distally. At this distal end, it 14 15 1113 appears to be firmly fused to the second sacral rib of the left side, a shorter element, 105 mm 16 1114 along the dorsal margin. The joint lateral facet measures 65 mm dorsoventrally high by 70 17 18 1115 mm anteroposteriorlyFor wide at theReview dorsal margin, and 45 Onlymm at the ventral margin. Young & 19 20 1116 Yeh (1963: fig. 3) show a putative portion of left sacral rib 3 forming part of this complex, 21 1117 but this cannot be seen in the specimen. Sacral ribs are seen on all vertebrae on the right side, 22 23 1118 but they are compressed to the midline, and lack their distal portions. The transverse 24 25 1119 processes and sacral ribs extend smoothly beneath and behind the prezygapophyses, and the 26 1120 junction between transverse process and rib is not clear. As preserved, these sacral ribs project 27 28 1121 posteriorly and ventrally, narrowing substantially distally, but their original length and 29 30 1122 orientation cannot be determined because of distortion and breakage. 31 1123 The first caudal vertebra in this block (Fig. 11), identified as a putative sixth sacral by 32 33 1124 Young & Yeh (1963: 208), but as a first caudal by Lee (1997: 240), is similar in overall shape 34 35 1125 to the fifth sacral, showing the same shape of centrum, much diminished zygapophyses, the 36 1126 prezygapophyses spanning little more than 55 mm in all measured mediolaterally, a tiny 37 38 1127 fraction of the span of the zygapophyses of the dorsal vertebrae. The transverse process and 39 40 1128 presumed fused rib appear short, but the distal end on the right side is damaged, and this 41 1129 structure is missing on the left. Young & Yeh (1963: 208-209) mention one other caudal 42 43 1130 vertebra of the holotype (IVPP V2717) and one of the paratype (IVPP V2718, missing), but 44 45 1131 they ‘are too imperfect for a detailed description’. 46 1132 47 48 1133 RIBS 49 50 1134 51 1135 A number of ribs and rib fragments of Huanghesaurus are preserved, some of them double- 52 53 1136 headed (IVPP V6722-17 to 19) and others single-headed (IVPP V6722-20 to 22). One 54 55 1137 double-headed rib, lacking its distal end (IVPP V6722-18; Fig. 12A, tu., ca.), shows the 56 1138 substantial tuberculum and smaller, projecting capitulum. This 188-mm long fragment 57 58 1139 measures 95 mm across the maximum spread of the articular heads and 40 mm deep. The 59 60 Page 35 of 85 Zoological Journal of the Linnean Society

35 1 2 3 1140 capitulum extends on a distinct lateral projection, some 50 mm long, extending from the side 4 5 1141 of the broader tuberculum. The single-headed ribs have elongate figure-of-eight articular 6 1142 facets that match the facets on transverse processes of presumed posterior dorsal vertebrae, 7 8 1143 such as IVPP V6722-20 (Fig. 12B). These articular facets vary from 71 mm along the 9 10 1144 maximum axis to 125 mm in IVPP V6722-22 (Fig. 12D). This last, most massive, of the 11 1145 several ribs, has a relatively straight shaft varying from 34–38 mm in maximum dimension, 12 13 1146 and showing the beginning of a deep groove on the posterior margin. This does not seem to 14 15 1147 correspond to any distal broadening of the rib, so Shihtienfenia did not have the derived 16 1148 condition of broadened ribs seen in Pumilopareia (Lee 1997, character 69). 17 18 1149 The double-headedFor ribs Reviewpresumably pertain to theOnly cervical or anterior dorsal vertebrae, 19 20 1150 and the single-headed ribs to the mid to posterior dorsals. Judging from comparisons with 21 1151 articulated pareiasaur skeletons (e.g. Seeley, 1889, 1892; Tsuji 2013), the most substantial rib 22 23 1152 (IVPP V6722-19) may come from the middle region of the torso, corresponding to the largest 24 25 1153 dorsal vertebrae, and perhaps the greatest mass of the torso region. 26 1154 27 28 1155 29 30 1156 SHOULDER GIRDLE AND FORELIMB 31 1157 32 33 1158 SCAPULOCORACOID 34 35 1159 36 1160 The scapulocoracoid of pareiasaurs is a three-part element, consisting of a scapula and two 37 38 1161 coracoid elements, often termed the anterior coracoid and coracoid (= posterior coracoid; = 39 40 1162 metacoracoid), whose homologies to the equivalent elements of turtles (Lee 1998) and 41 1163 mammals (Vickaryous & Hall 2006) are complex and debated. Here, we term these two 42 43 1164 elements the anterior and posterior coracoids respectively, and regard the acromion process of 44 45 1165 the scapula as equivalent to that of other basal amniotes, and not a modified anterior coracoid 46 1166 (Lee 1998). 47 48 1167 The right scapula of Shihtienfenia (IVPP V2717) is a long slender element, seemingly 49 50 1168 more or less complete because it lacks broken edges (Fig. 13; Young & Yeh 1963: fig. 6). 51 1169 The element is maximally 630 mm dorsoventrally long, of which 450 mm forms the scapular 52 53 1170 blade, and 180 mm the acromion process and glenoid. The distal end of the blade apparently 54 55 1171 tapers to a rather rounded distal termination; the margins of the distal end are partly repaired 56 1172 with plaster, but sufficient of the edges are original to suggest the shape is about right. The 57 58 1173 distal portion of the blade is flat and slightly spoon-shaped, and the blade thickens proximally 59 60 Zoological Journal of the Linnean Society Page 36 of 85

36 1 2 3 1174 in a mediolateral orientation from 15 mm to 20 mm, and 35 mm proximally, at which point it 4 5 1175 measures 77-80 mm wide anteroposteriorly. The lateral face of the scapular blade shows 6 1176 coarse longitudinal striations. On the medial face, the distal end is roughened, and the 7 8 1177 remainder shows similar coarse longitudinal striations, including a large, irregular midline 9 10 1178 ridge. 11 1179 Proximally, the anterior margin of the scapular blade broadens and extends into the 12 13 1180 acromion process on the anterior margin (Fig. 13A, B, D, acr.) and an internal process seen in 14 15 1181 medial view (Fig. 13D, int.pr.). The acromion process is massive, located on the anterior 16 1182 scapular margin, and with a roughened boss some 55 mm dorsoventrally long and 25 mm 17 18 1183 mediolaterally wideFor at most. The Review internal process is slightly Only broken, but extends as a broad 19 20 1184 ridge to the coracoidal margin. The proximal portion of the scapula is 115 mm 21 1185 anteroposteriorly wide at the level of the acromion, and up to 60 mm mediolaterally deep. It 22 23 1186 narrows slightly to 95 mm and 55 mm respectively, and expands towards the glenoid, which 24 25 1187 is incomplete and cannot be described clearly. 26 1188 The left scapula consists of a blade and a separate portion of the fused proximal 27 28 1189 scapula, anterior coracoid, and posterior coracoid (Fig. 14; Young & Yeh 1963: fig. 7, right). 29 30 1190 The scapular blade is preserved for 460 mm from acromion to distal end, which is irregularly 31 1191 broken. This is equivalent to the length on the right side above the acromion, so 32 33 1192 interpretations of the distal end of the former might require care. On the left side, there is no 34 35 1193 sign of thinning, nor of the apparently spoon-shaped expanded and curved distal end seen on 36 1194 the right. As preserved, the left scapular blade narrows from 120 mm distally to 85 mm 37 38 1195 proximally, measured anteroposteriorly. At the same time, the blade thickens from 30 mm 39 40 1196 deep mediolaterally at the distal end to 75 mm in line with the acromion. This creates a 41 1197 somewhat cylindrical scapular blade, especially proximally (Lee 1997). Anterior and posterior 42 43 1198 margins of the scapular blade are nearly straight. On the anterior margin, the acromion and 44 45 1199 medial internal process form roughly equal-sized processes on either side of the clavicle. The 46 1200 roughened distal face of the acromion measures 80 x 25 mm. Below the acromion, the scapula 47 48 1201 expands to an anteroposterior width of about 200 mm, partly by an anterior flange, but mainly 49 50 1202 through the upper portion of the glenoid facet (Fig. 14A, gl.). 51 1203 Sutures between scapula, posterior coracoid, and anterior coracoid are hard to 52 53 1204 distinguish in lateral view (Fig. 14A), and they are entirely obscured in medial view. Further, 54 55 1205 the anterior, ventral, and posterior margins of the posterior coracoids are missing, so their 56 1206 original dimensions cannot be determined. At most, the anterior coracoid-posterior coracoid 57 58 1207 plate measures 270 mm anteroposteriorly. The glenoid (Fig. 14A, gl.) is a broad and deeply 59 60 Page 37 of 85 Zoological Journal of the Linnean Society

37 1 2 o 3 1208 concave articulation face with its long axis oriented at approximately 45 above horizontal. 4 5 1209 The glenoid measures 210 mm long at most along this long axis, and 105 mm wide, measured 6 1210 orthogonally to the long axis. A large, deep coracoid foramen (Fig. 14A, co.f.) is located just 7 8 1211 anterior to the glenoid and it penetrates the posterodorsal portion of the anterior coracoid 9 10 1212 deeply. In medial view (Fig. 14B), the scapulocoracoid presents a smooth aspect, with no 11 1213 evidence of the sutures dividing scapula from posterior coracoid and anterior coracoid, but the 12 13 1214 groove to the subscapular fossa and the deep foramen, which connects with the coracoid 14 15 1215 foramen are evident. 16 1216 The left scapulocoracoid of Huanghesaurus (IVPP V6722-22) presents similar 17 18 1217 characters (Gao 1983:For fig. 197), Review but is one-quarter again Only larger. The whole specimen (Fig. 19 20 1218 15A–D) is at most 870 mm long, of which the scapular blade is about 600 mm. The distal end 21 1219 is incomplete, and has a maximum anteroposterior width of 190 mm. The blade is roughly 22 23 1220 straight-sided, but it narrows to a minimum anteroposterior width of 95 mm, and expands to 24 25 1221 130 mm just above the acromion process. The blade is flattened distally, becoming more 26 1222 cylindrical proximally. The acromion process is set on a pedestal projecting from the anterior 27 28 1223 margin of the scapula (Fig. 15C, D, acr.), and the medial part of the scapula expands 29 30 1224 anteriorly. The glenoid is steeply angled from anterodorsal to posteroventral, and measures 31 1225 210 x 105 mm, with a twist halfway along its length. In lateral view, the anterior and posterior 32 33 1226 coracoids (Fig. 15A, B, aco., pco.) have incomplete ventral margins, and they seem to have 34 35 1227 been of similar dimensions. The coracoid foramen penetrates the posterodorsal angle of the 36 1228 anterior coracoid in lateral view (Fig. 15B, D, co.f.), and passes upwards to emerge in the 37 38 1229 middle of the basal portion of the scapula, in medial view. The sutures between all three 39 40 1230 elements can just be discerned in lateral view, but they are invisible in medial view (Fig. 41 1231 15C). The medial face is uniform and smooth, interrupted only by the substantial subscapular 42 43 1232 foramen, which measures 40 x 20 mm in diameter. 44 45 1233 The left scapulocoracoid of Shansisaurus xuecunensis (CAGS V301), as illustrated 46 1234 (Cheng 1980: fig. 19; pl. 1, fig. 1), shows the same overall shape, size, proportions, and detail 47 48 1235 as in that of Huanghesaurus (Gao 1983: fig. 4). The scapular blade is long and tapers slightly, 49 50 1236 while its cross-sectional shape changes from rather flattened at the distal end, to more 51 1237 cylindrical proximally. The acromion is projected on a distinct square process, and has a 52 o 53 1238 distinct facet. The glenoid is angled at some 30 above horizontal and is distributed almost 54 55 1239 equally between scapula and posterior coracoid. The anterior coracoid is of similar 56 1240 dimensions to the posterior coracoid in lateral view, and it carries the exit of the coracoid 57 58 1241 foramen in its extreme posterodorsal corner, close to the junction of all three elements. 59 60 Zoological Journal of the Linnean Society Page 38 of 85

38 1 2 3 1242 An incomplete right scapulocoracoid, IVPP V6727 (Fig. 15E, F), was assigned by 4 5 1243 Gao (1989: 1238-1239) to Shansisaurus sp., and he identified some diagnostic features, 6 1244 namely ‘a long, narrow, and internally curved scapular blade; a weakly developed and low- 7 8 1245 positioned acromion; and a distinct precoracoid foramen, the internal opening of which is 9 10 1246 located entirely in the anterior coracoid’. These are, however, all features seen widely among 11 1247 pareiasaurs, and indeed in many basal tetrapods, and cannot distinguish Shansisaurus from 12 13 1248 Shihtienfenia. The specimen shows the proximal portion of the scapula and much of the 14 15 1249 anterior coracoid, but it lacks the margins of the latter, the posterior coracoid is missing, and 16 1250 the glenoid fossa is badly damaged. The coracoids are in the same plane as the scapula, and 17 18 1251 the suture between Foranterior coracoid Review and scapula is firmly Only fused, but still detectable laterally 19 20 1252 as a fine interdigitating suture line running from the anterior margin to the glenoid. The 21 1253 anterior coracoid is a broad flat plate in lateral view (Fig. 15E, aco.), and it bears a large 22 23 1254 coracoid foramen in its posterior portion, measuring 20 mm across (Fig. 15E, co.f.). The 24 25 1255 anterior coracoid thickens posterodorsally towards the glenoid, but this region is damaged and 26 1256 its original location and shape cannot be identified. The scapula has a massive proximal 27 28 1257 portion, 80 mm thick mediolaterally at the glenoid region. The base, as preserved, is 140 mm 29 30 1258 anteroposteriorly wide, and at most 255 mm ventrodorsally long, from the posterior coracoid- 31 1259 scapula suture to the broken distal end of the scapular blade. There is a massive, rectangular 32 33 1260 acromion process (Fig. 15E, F, acr.), rugose and 70 mm along its longest axis, extending 34 35 1261 substantially laterally from the scapula. In addition, the anterior, narrow margin of the lower 36 1262 portion of the scapula also extends as a rectangular process, with a 38 mm long rugose 37 38 1263 surface, and beginning 53 mm above the scapula-anterior coracoid suture. Above the 39 40 1264 acromion, the preserved portion of the scapular blade is of approximately equal 41 1265 anteroposterior width, measuring 70-75 mm, and 35 mm medio-laterally deep at the centre of 42 43 1266 the blade, which is marked by a gentle midline ridge. In medial view (Fig. 15F), the whole 44 45 1267 preserved portion of the scapulocoracoid is remarkably smooth and uniform, and the main 46 1268 feature is the very obvious and deep subscapular fossa (Fig. 15F, s.s.f.), which penetrates at 47 48 1269 the middle of the ventral margin of the scapula, on the faint interdigitating suture line between 49 50 1270 scapula and anterior coracoid. This fossa is at the ventral end of a slight channel down the 51 1271 medial face of the scapula, and the canal opening enters the anterior coracoid medially and 52 53 1272 exits as the coracoid foramen. 54 55 1273 An isolated left scapula (IVPP V8533), assigned by Gao (1989: 1239, pl. 2K) to 56 1274 ‘Pareiasauride gen. et sp. indet.’, is a long, slender, strap-like element, 85 mm antero- 57 58 1275 posteriorly wide at the base of the blade, narrowing to 73 mm at mid-length, and expanding 59 60 Page 39 of 85 Zoological Journal of the Linnean Society

39 1 2 3 1276 distally to a maximum of 107 mm (Fig. 15G, H). The whole specimen is some 400 mm long, 4 5 1277 and it lacks the glenoid region, the contacts with the coracoids, and the distalmost parts of the 6 1278 blade. The scapula blade is a thin plate of bone, the primitive condition (Lee 1997, character 7 8 1279 76), and not cylindrical as in some derived pareiasaurs. There is a modest acromion process 9 10 1280 on the anterior margin (Lee 1997, character 74), and behind it, visible in medial view (Fig. 11 1281 15H), the base of another process, broken off. There is no groove on the anterior margin of 12 13 1282 the blade for a cleithrum. 14 15 1283 These scapulocoracoids provide several phylogenetically informative characters, and 16 1284 they appear to be identical in all three nominal ‘taxa’: there is an acromion process on the 17 18 1285 anterior surface of Forthe scapula (LeeReview 1997, character 74; TsujiOnly 2013, character 68); the scapular 19 20 1286 blade is very long, with a length at least three times the diameter of the glenoid fossa (Lee 21 1287 1997, character 75; Tsuji 2013, character 69); and the dorsal edge of the posterior coracoid is 22 o 23 1288 almost horizontal, and meets the posterior border of the scapula at an angle of less than 135 24 25 1289 (Lee 1997, character 77; Tsuji 2013, character 70). This last character has been coded as 26 1290 derived in previous studies, but it is hard to determine because it depends on the orientation of 27 28 1291 the scapulocoracoid, whether with scapular blade vertical or pointing posterodorsally. With 29 30 1292 the scapular blade vertical, as shown by Lee (1997: fig. 12), there is a distinct shift from a 31 1293 more or less horizontal suture line to one that runs at about 45o in a posterodorsal direction 32 o 33 1294 (equivalent to the 135 angle – measured from the anterior orientation - mentioned in previous 34 35 1295 character definitions). In the Chinese pareiasaurs, the sutures are hard to determine in the 36 1296 specimens thanks to extensive fusion. Although Cheng (1980: fig. 19) shows the posterior 37 o 38 1297 coracoid-scapular contact at an angle of about 30 in Shansisaurus, the angle is near- 39 40 1298 horizontal in Shihtienfenia and Huanghesaurus (Figs. 14, 15). 41 1299 42 43 1300 DERMAL SHOULDER GIRDLE 44 45 1301 46 1302 The dermal shoulder girdle of Shihtienfenia (IVPP V 2717) is represented by both clavicles, 47 48 1303 but no interclavicle. The clavicles are elongate, slender elements, each some 530 mm long 49 50 1304 and with a blade 70 mm anteroposteriorly long distally, and 80 mm proximally (Fig. 14B, 51 1305 16A). The clavicle begins proximally as a flat, bladed element that fitted into the anterior 52 53 1306 facet of the (missing) interclavicle, then turns gently in line with the broadly semi-circular 54 55 1307 cross section of the whole pectoral girdle, terminating in a distal rod-like structure. As 56 1308 reconstructed, the posterior margin of the clavicle sits close to the anterior margin of the 57 58 1309 scapula, with the acromion process located laterally, and the medial internal process medially 59 60 Zoological Journal of the Linnean Society Page 40 of 85

40 1 2 3 1310 (Figs. 13D, 16A, acr., int.pr.). There is no slot or distinct marking on the anterior margin of 4 5 1311 the scapula for the clavicles, so they presumably did not adhere closely in life. 6 1312 This is confirmed by the dermal shoulder girdle of Huanghesaurus, which is 7 8 1313 represented by a pair of clavicles, but also a well-preserved interclavicle. A cleithrum occurs 9 10 1314 in the pareiasaurs Embrithosaurus and Bradysaurus, but has not been identified among the 11 1315 materials of Shihtienfenia, and the absence of a groove on the anterior margin of the scapula 12 13 1316 suggests there was no cleithrum (Lee 1997, character 79; Tsuji 2013, character 71). 14 15 1317 The right and left clavicles of Huanghesaurus (IVPP V6722-23, 24) are both elongate, 16 1318 blade-like elements (Fig. 16B–E) that fitted tightly into the anterior groove on the 17 18 1319 interclavicle, and metFor each other Review in the midline of that element.Only The right clavicle is 515 mm 19 20 1320 long mediolaterally, and at most 120 mm deep anteroposteriorly at the proximal end. The 21 1321 clavicle narrows to 65 mm deep anteroposteriorly at mid-shaft, and the distal end is 62 mm 22 23 1322 deep. Proximally, the clavicle shows a long, narrow process on the dorsal (interior) surface 24 25 1323 (Fig. 16D, icl.pr. r.cl.) that fits snugly into the anterior groove on the interclavicle. The 26 1324 clavicle has a broad, rounded anterior portion, up to 50 mm deep dorsoventrally, that runs 27 28 1325 from the proximal to the distal end, and provides the structural strength of the element. The 29 30 1326 anterior portion is demarcated from the posterior flange of the clavicle, which is 15-20 mm 31 1327 thick dorsoventrally. The posterior flange (Fig. 16E, p.fl.) forms a deep slot at the proximal 32 33 1328 end, and the exact shape of the anterior margin of the posterior flange matches the anterior 34 35 1329 margin of the interclavicle. Distally, the posterior flange of the clavicle expands posteriorly 36 1330 into a short, 70 mm long mediolaterally oriented blade. This, and the middle and distal parts 37 38 1331 of the posterior flange acted as the major site of origin for the pectoralis muscle. The distal 39 40 1332 end of the clavicle is marked by the loss of the posterior flange, and a twist of the anterior 41 1333 margin to form a rounded tongue-like termination, covered in a sculptured region of 42 43 1334 longitudinally oriented irregular ridges, each 2-3 mm wide. The ventral (exterior) surface of 44 45 1335 the clavicle (Fig. 16C) shows a uniform, smoothly curved appearance, and a distinct tapering 46 1336 to the distal end. 47 48 1337 The single, substantial interclavicle of Huanghesaurus (IVPP6722-25) is preserved 49 50 1338 more or less complete, lacking just the distal end of the left-hand anterior process (Fig. 16F, 51 1339 G). The whole element measures 345 mm wide across the anterior processes, and 310 mm 52 53 1340 anteroposteriorly, so showing the derived condition of a long anterior processes (Lee 1995; 54 55 1341 1997, character 80). The anterior part of the interclavicle bears a deep facet for reception of 56 1342 the clavicles along its entire width (Fig. 16F, cl.f.). This facet has a roughened surface, and 57 58 1343 radiating ridges and grooves at the lateral ends, and there is a distinct lip at the midline 59 60 Page 41 of 85 Zoological Journal of the Linnean Society

41 1 2 3 1344 posterior margin, which overlapped the clavicles ventrally when they were in place. The 4 5 1345 posterior portion of the interclavicle is a short tongue-shaped structure, 92 mm wide at its 6 1346 narrowest, and 135 mm at its widest. The posterior process (Fig. 16F, G, p.pr.) is thickest in 7 8 1347 the centre, measuring 35 mm ventrodorsally. The posterior margin of the posterior process is 9 10 1348 curved around the arc of a circle, and it bears deep radial grooves, seen in both external 11 1349 (ventral) and internal (dorsal) views. These radial grooves are seen only along the posterior 12 13 1350 margin, and all are oriented anteroposteriorly, and they are deepest on the dorsal face. These 14 15 1351 were presumably structures for the attachment of parts of the pectoralis muscle, and were 16 1352 adapted to withstand substantial stresses and strains. 17 18 1353 Together, theFor three dermal Review elements of the shoulde Onlyr girdle formed a powerful 19 20 1354 supporting structure beneath the thorax, and the clavicles presumably met the anterior margin 21 1355 of the scapular blade at mid-length. The initial reconstruction (Fig. 16H, I), based on IVPP 22 23 1356 V2717 (Young and Sun 1963, pl. 1, 2), shows the broad thorax surrounded by clavicles below 24 25 1357 and scapulae round the sides. Here, the interclavicle is missing, but it would have bound the 26 1358 clavicles together into a powerful ventral cuirass that also provided the origin of the 27 28 1359 substantial pectoralis muscle. 29 30 1360 31 1361 HUMERUS 32 33 1362 34 35 1363 In the description of the humerus and femur, I use the terms ventral, dorsal, anterior, and 36 1364 posterior, assuming the limb is at rest, and in sprawling pose. Both humeri of the type 37 38 1365 specimen of Shihtienfenia (IVPP V2717) are preserved, the left essentially complete, and the 39 40 1366 right as a much distorted proximal portion that shows the proximal articular face, measuring 41 1367 180 x 60 mm. The description is devoted to the left humerus (Fig. 17A–D), some 400 mm 42 43 1368 long, with an expanded proximal end, 295 mm wide at most, and an expanded distal end, 250 44 45 1369 mm wide at most, and with a twist of the shaft that sets the major planes of the two articular 46 1370 ends at an angle of 45o to each other. The proximal articular end carries the articulation for the 47 48 1371 glenoid of the scapulocoracoid, an elongate facet up to 210 mm long and 70 mm wide at the 49 50 1372 middle point (Fig. 17A–D, a.f.). The articular facet has narrow distal ends, and it rolls from 51 1373 proximally- to proximodorsally-facing in the anterior portion. In dorsal view, the proximal 52 53 1374 articular end of the humerus is roughly square, with the anterior dorsoventral prominent ridge 54 55 1375 that separates an anterodorsal face from the remainder of the proximal humerus. In ventral 56 1376 view (Fig. 17A), the proximal end of the humerus shows a flaring posterior and middle 57 58 1377 portion, and a massively thickened anterior margin that extends into the deltopectoral crest 59 60 Zoological Journal of the Linnean Society Page 42 of 85

42 1 2 3 1378 (Fig. 17A–C, dpc.), which projects as a substantial boss about halfway down the length of the 4 5 1379 humerus. The narrow humeral shaft is oval, measuring 80 x 65 mm in diameter. The flared 6 1380 distal end of the humerus shows a damaged entepicondylar region, but a large and delicate 7 8 1381 ectepicondylar lamina extending on the dorsal face, for the distalmost 170 mm of the humerus 9 10 1382 (Fig. 17C, ect.). This terminates proximally as a thin lamina. Young and Yeh (1963, p. 210) 11 1383 noted that there is an entepicondylar groove, which runs parallel to the shaft orientation, on 12 13 1384 the anterior face of the lamina, but no ectepicondylar foramen. However, at the proximal end 14 15 1385 of the ectepicondylar groove, there is a distinct pocket or pit that has been scooped out by the 16 1386 preparators (Fig. 17B, ect.) – it is in the correct location to be an ectepicondylar foramen, but 17 18 1387 it is impossible to sayFor whether thisReview might indeed be a foramen Only or not. Suffice to say that all 19 20 1388 other pareiasaurs appear to possess such a foramen (Lee 1997, p. 237). In posterior view (Fig. 21 1389 17D, ect., ent.), the ectepicondylar lamina provides a squared margin to the dorsal edge of the 22 23 1390 distal end of the humerus, the entepicondylar projection being less complete. The supinator 24 25 1391 process, forming part of the ectepicondylar lamina, projects (Fig. 17D, sup.). The distal end of 26 1392 the humerus is damaged, so the tibial and fibular condyles cannot be clearly distinguished. 27 28 1393 The left humerus of Huanghesaurus (IVPP V6722-26) is a massive element, with 29 30 1394 more or less complete proximal end, but lacking the distal articular end (Fig. 17E, F). The 31 1395 bone is at most 350 mm long, as preserved. The massively expanded proximal portion is up to 32 33 1396 360 mm across anteroposteriorly, and the shaft narrows to 85 mm, and the distal end expands 34 35 1397 again to 145 mm. In dorsal view (Fig. 17E), the anterior margin is marked by a massive 36 1398 process with a deeply roughened surface. Behind, there is a distinct and rather straight 37 38 1399 anterior dorsoventral line (Fig. 17E, a.d.v.l.) that marked areas for major dorsal musculature, 39 40 1400 the deltoid insertion on the deltopectoral crest portion, and the latissimus dorsi and triceps on 41 1401 the other side. This structure is a raised, broad ridge that separates the two planes of the 42 43 1402 anterior portion of the humerus. In the posterior portion is the deltopectoral crest (Fig. 17E, F, 44 45 1403 dpc.), an irregular ridge that wraps around from the posterior margin. In ventral view (Fig. 46 1404 17F), the expanded proximal end of the humerus is broadly convex and apparently 47 48 1405 featureless. 49 50 1406 The proximal articular facet is located entirely along the proximal margin of the 51 1407 element, with only its posteriormost portion visible in ventral view (Fig. 17F, p.a.f.). The face 52 53 1408 is elongate, 225 mm mediolaterally long in all, with a narrow anterior portion and a broader 54 55 1409 posterior portion, up to 82 mm across, which shows a distinct corkscrew twist, matching the 56 1410 natural rolling motion of the humerus as the forearm moves position in the typical sprawling 57 58 1411 pareiasaur posture. The humerus shows torsion, the long axis of the proximal articular head 59 60 Page 43 of 85 Zoological Journal of the Linnean Society

43 1 2 o 3 1412 set at about 60-70 to the distal, but the absence of the distal articular facets makes this 4 5 1413 uncertain. 6 1414 The distal end of the humerus, although missing the articular condyles, shows distinct 7 8 1415 ectepicondylar and entepicondylar expansions. These lie on either side of the deep 9 10 1416 anterodorsally located intercondylar fossa (= trochlear fossa; olecranon fossa; Fig. 17E, ic.f.), 11 1417 the deep channel in which the substantial olecranon of the ulna could move. The 12 13 1418 entepicondyle consists of a narrow bone rod that encompasses an entepicondylar foramen 14 15 1419 (Fig. 17F, ent.f.). The proximal part of the encompassing bone rod is original, but the distal 16 1420 part of the rod has been remodelled in plaster, so its original dimensions are not certain. 17 18 1421 Nonetheless, the proximalFor portion Review shows that the entepicondylar Only foramen was entirely 19 20 1422 surrounded by bone, measured 32 x 10 mm, and angled from an antero-distal to a postero- 21 1423 proximal orientation. The ectepicondyle projects substantially dorsally as a broad process 22 23 1424 with an external margin that forms a helical curve that terminates with an antero-dorsally 24 25 1425 sweeping point, the supinator process (Fig. 17E, ect., sup.). The ectepicondylar foramen (Gao 26 1426 1983, fig. 5) has been excavated into the bluish sediment that invests the broken distal end of 27 28 1427 the humerus, so its original dimensions, including depth, are uncertain. Indeed, the bone 29 30 1428 edges are not clear, so it cannot be claimed with certainty that this is an original structure. 31 1429 A further essentially complete left humerus (IVPP V8534) was identified by Gao 32 33 1430 (1989: 1239, pl. 2L) as ‘Pareiasauride gen. et sp. indet.’ The element is flattened and 34 35 1431 distorted, and lacks the articular ends, so it is hard to assess the degree of torsion of the 36 1432 humerus: both articular ends lie in the same plane. As preserved (Fig. 17G), the humerus 37 38 1433 measures 435 mm long, and it has a hugely expanded proximal end, up to 265 mm across, and 39 40 1434 this narrows dramatically about 230 mm from the proximal margin to a distal shaft measuring 41 1435 71 mm in maximum dimension at its narrowest, and expanding distally to measure 140 mm. 42 43 1436 In ventral view, the distinct facet for articulation with the scapulocoracoid measures 100 x 45 44 45 1437 mm. The deltopectoral crest forms part of the hugely flared proximal end. The condition of 46 1438 preservation does not allow any consideration of entepicondylar and entepicondylar foramina, 47 48 1439 nor of the distal articulation facets. 49 50 1440 Of the phylogenetically informative characters of the humerus, the humeri of 51 1441 Shihtienfenia and Huanghesaurus show: torsion such that the expanded proximal and distal 52 o 53 1442 ends stand at an angle of less than or equal to 45 (Lee 1997, character 81; Tsuji 2013, 54 55 1443 character 72); the ectepicondyle is expanded and forms a wide rectangular flange that projects 56 1444 in front (preaxially) of the radial condyle (Lee 1997, character 82; Tsuji 2013, character 73); 57 58 1445 there is no ectepicondylar foramen (Lee 1997, character 83; Tsuji 2013, character 74); the 59 60 Zoological Journal of the Linnean Society Page 44 of 85

44 1 2 3 1446 entepicondyle is rounded, narrow, and with a reduced distal expansion (Lee 1997, character 4 5 1447 84; Tsuji 2013, character 75); the entepicondylar foramen is present in the form of an open 6 1448 groove in Shihtienfenia, and apparently as a fully enclosed structure in Huanghesaurus, 7 8 1449 although the area has been much repaired (Lee 1997, character 85; Tsuji 2013, character 76); 9 10 1450 the entepicondylar foramen is situated on the side of the epicondyle and is feebly exposed in 11 1451 dorsal view (Lee 1997, character 86; Tsuji 2013, character 77; wrongly coded 0 by Lee 1997); 12 13 1452 the entepicondyle and ectepicondyle do not project distally beyond the epicondylar region, in 14 15 1453 Shihtienfenia at least (Lee 1997, character 87; Tsuji 2013, character 78); there is a transverse 16 1454 ridge on the intercondylar depression on the distal humerus, defined dorsally by the ulnar 17 18 1455 articular surface (LeeFor 1997, character Review 88; Tsuji 2013, character Only 79); the ulnar articulation 19 20 1456 surface of the humerus takes the form of a groove bordered posteriorly by a faint ridge, with 21 1457 no expansion (Lee 1997, character 89; Tsuji 2013, character 80); and the radial condyle of the 22 23 1458 humerus is hemispherical and located entirely on the ventral surface of the humerus (Lee 24 25 1459 1997, character 90; Tsuji 2013, character 81). Characters 78-81 cannot be coded in 26 1460 Huanghesaurus because the distal end of the humerus is damaged. 27 28 1461 29 30 1462 ULNA AND RADIUS 31 1463 32 33 1464 A largely complete, but crushed, left ulna of Huanghesaurus (IVPP V6722-27) is striking 34 35 1465 because of the massive olecranon portion (Fig. 18A, B., ole.), the primitive condition for 36 1466 pareiasaurs (Lee 1997, character 91). The ulna is 535 mm long, but lacks the proximalmost 37 38 1467 and distalmost articular terminations. The proximal expanded portion of the ulna extends for 39 40 1468 nearly half its length (260 mm) and is at most 170 mm antero-posteriorly broad, which may 41 1469 be partially exaggerated by the flattening, and the shaft narrows to 62 mm, before expanding 42 43 1470 slightly distally to 80 mm. In lateral (external) view (Fig. 18A), the ulna shows the two 44 45 1471 sigmoid processes of similar dimensions, defining a narrow sigmoid notch (= radial notch), 46 1472 which in life received the head of the radius. The anterior margin of the ulna is rounded in 47 48 1473 section and describes a gentle curve, whereas the posterior margin is marked by a distinct 49 50 1474 ridge, extending distally from the olecranon for 140 mm. In medial (internal) view (Fig. 18B), 51 1475 the ulna shows a flat proximal portion with some longitudinal cracks suggesting crushing 52 53 1476 during fossilisation. The posterior distal flange is demarcated from the main shaft. The 54 55 1477 expanded olecranon and medially facing proximal articular surface of the ulna indicate the 56 1478 primitive condition for Tsuji’s (2013) character 82 (= Lee’s 1997 character 91). 57 58 59 60 Page 45 of 85 Zoological Journal of the Linnean Society

45 1 2 3 1479 The left radius of Huanghesaurus (IVPP V6722-28; Fig. 18C, D) is shorter than the 4 5 1480 ulna, measuring 385 mm long, but lacking the articular ends. The element has expanded ends, 6 1481 the proximal measuring 125 x 80 mm, the distal 135 x 85 mm, and the shaft narrowing to 57 x 7 8 1482 40 mm at mid-length. The element bears a marked, but damaged, expansion on the lateral 9 10 1483 (external) face (Fig. 18C) at the proximal end, which runs into a narrow diagonal ridge 11 1484 extending at least halfway down the shaft, but is relatively flat on the medial (internal) face 12 13 1485 (Fig. 18D). There is also a broad ridge in the midline towards the distal end. Both ends of the 14 15 1486 radius are deeply excavated, and filled with sediment, indicating loss of the epipophyses 16 1487 before fossilisation. 17 18 1488 For Review Only 19 20 1489 21 1490 PELVIC GIRDLE AND HINDLIMB 22 23 1491 24 25 1492 PELVIC GIRDLE 26 1493 27 28 1494 The pelvic girdle is represented by the fused elements of both sides in Shihtienfenia (IVPP 29 30 1495 V2727), of which the left side is almost complete, and the right side less so, with the lower 31 1496 borders of pubis and ischium being damaged. The left side of the pelvis (Fig. 19A, B) is 32 33 1497 massive and compact. The whole pelvis is firmly fused, and measures some 430 mm in 34 35 1498 dorsoventral height from the anterior tip of the iliac blade to the ventral public margin at the 36 1499 anterior end and 370 mm from the posterior tip of the iliac blade to the ventral ischiadic 37 38 1500 margin at the posterior. The dorsal blade of the ilium has a substantial anterior process (Fig. 39 40 1501 19A, B, ant.pr.), and the blade slopes steeply posteroventrally, being 320 mm long in all. The 41 1502 dorsal margin is massive, 60 mm mediolaterally thick at the everted and horizontally oriented 42 43 1503 anterior process, but tapering to 25 mm at the posterior process. Ventrally, the ilium narrows 44 45 1504 to 125 mm wide anteroposteriorly at the neck, and expands to 150 mm at the level of the 46 1505 acetabulum. The whole ilium slopes well forwards with respect to the horizontal dorsal 47 48 1506 margin of the iliac blade. The acetabulum (Fig. 19A, ac.) is nearly perfectly circular, 49 50 1507 measuring about 160 mm across in every dimension from the high point of the surrounding 51 1508 lip. It is generally shallow, but deepens to 40 mm beneath a marked expansion, or buttress, on 52 53 1509 the dorsal iliac margin. The sutures with pubis and ischium are heavily fused, but can still be 54 55 1510 determined approximately. 56 1511 In medial view (Fig. 19B), the left ilium shows a groove above the posteroventral 57 58 1512 margin of the blade. Along the dorsal blade margin is a groove sloping posteroventrally in the 59 60 Zoological Journal of the Linnean Society Page 46 of 85

46 1 2 3 1513 anterior portion, associated with sacral ribs 1 and 2, and below it lies a ridge, the crista 4 5 1514 sacralis (Hartmann-Weinberg 1933, 1937; Lee 1997: 240; Fig. 19B, cr.sac.). There is a 6 1515 fragment, possibly of sacral rib 2 still adhering in the anteroventral angle. Anteriorly, and still 7 8 1516 close to the dorsal blade margin are more fragments of sacral ribs, presumably ribs 3 and 4. 9 10 1517 The fourth rib is quite substantial (Fig. 19B, s.r.4), measuring 85 mm anteroposteriorly and 52 11 1518 mm dorsoventrally, and narrowing from its flared distal end to dimensions of 30 x 25 mm 12 13 1519 respectively at 75 mm medially from the medial face of the iliac blade. 14 15 1520 In lateral view, the ilium expands more or less symmetrically around the circular 16 1521 acetabulum, leaving a margin of some 30 mm anteriorly and posteriorly. The somewhat fused 17 18 1522 contacts between theFor three pelvic Review elements can be discerned Only (Fig. 19A, il., is., pu.). The pubis 19 20 1523 and ischium are relatively modest-sized elements, the former appearing to lack its anterior and 21 1524 ventral margins. The pubis carries a slightly smaller portion of the ventral part of the 22 23 1525 acetabulum than the ischium, if their sutured contact is correctly identified. The ischium has a 24 25 1526 modest posteroventral process, whose distal end is missing. In medial view (Fig. 19B), the 26 1527 surface behind the acetabulum, and the medial faces of pubis and ischium, are relatively 27 28 1528 smooth and featureless, and the bone contacts cannot be seen. The maximum anteroposterior 29 30 1529 length of the puboischiadic plate, missing anterior and posterior projections, is 245 mm. 31 1530 The right pelvic plate (Fig. 19C, D) is rather less complete, lacking the distal ends of 32 33 1531 the iliac blade and most of the pubis and ischium below the ventral margin of the acetabulum. 34 35 1532 It appears to show similar features to the left pelvic plate, measuring 280 mm 36 1533 anteroposteriorly along the iliac blade, and 265 mm at most across the ischiopubis. 37 38 1534 Dorsoventral heights are 420 mm anteriorly and 340 mm posteriorly, and the acetabulum is 39 40 1535 circular and 160 mm in diameter, as on the left side. The acetabulum is deepest in its dorsal 41 1536 portion. Most of the features in medial view (Fig. 19D) are the same as on the left pelvic 42 43 1537 plate, except that the sacral rib attachments are less clear. From the distal end of the anterior 44 45 1538 process, a deep groove runs posteroventrally on the medial face of the iliac blade. Further 46 1539 ventrally, below the 120 mm anteroposterior waist of the pelvic plate, there appears to be a 47 48 1540 twist, with a broad process sweeping across the posterior ventral portion of the ilium and 49 50 1541 across to the posteroventral point of the ischium. Near the anterior margin, the ilium forms a 51 1542 slightly overturned and flattened area and a distinct broad, vertical groove and process 52 53 1543 descends across the posterior portion of the pubis. 54 55 1544 The pelvis of Shihtienfenia provides evidence about a number of phylogenetically 56 1545 informative characters: the crista sacralis of the ilium is a well developed ridge (Lee 1997, 57 58 1546 character 95; Tsuji 2013, character 85); the iliac shaft is inclined anterodorsally, forming an 59 60 Page 47 of 85 Zoological Journal of the Linnean Society

47 1 2 o 3 1547 angle with the vertical of more than 20 (Lee 1997, character 96; Tsuji 2013, character 86); 4 5 1548 the iliac blade is expanded well anterior of the iliac shaft (Lee 1997, character 97; Tsuji 2013, 6 1549 character 87); the anterior extent of the ilium is concave along the vertical dimension and the 7 8 1550 anteroventral margin is strongly everted, even pointed looking and oriented almost 9 10 1551 horizontally (Lee 1997, character 98; Tsuji 2013, character 88); the posterior process of the 11 1552 iliac blade is strongly reduced (Lee 1997, character 99; Tsuji 2013, character 89); the dorsal 12 13 1553 buttress on the acetabulum is strongly developed (Lee 1997, character 100; Tsuji 2013, 14 15 1554 character 90); and the edge of the acetabulum is anteriorly rounded or slightly oval (Lee 1997, 16 1555 character 101; Tsuji 2013, character 91). 17 18 1556 For Review Only 19 20 1557 HINDLIMB ELEMENTS 21 1558 22 23 1559 The only identified hindlimb element of any of the Shanxi pareiasaurs is an incomplete left 24 25 1560 femur of the Shansisaurus xuecunesis holotype (CAGS V301, not currently accessible; Cheng 26 1561 1980: fig. 20; pl. 2, fig. 1). This element (Fig. 19E, F) was robust, and it measured 420 mm 27 28 1562 long. If complete, the proximal end would have been about 168 mm wide, narrowing to 92 29 30 1563 mm at mid-shaft, and expanding distally to 184 mm. In dorsal view (Fig. 19E), the twist of 31 1564 the narrow, and somewhat flattened shaft is clear, as is the intercondylar groove between 32 33 1565 tibial and fibular facets. The ventral view of the proximal face (Fig. 19F, i.tr., tr.m.) shows the 34 35 1566 incurved internal trochanter near the posterior margin, but the anterior margin with the 36 1567 trochanter major is missing. Between them lies a broad, concave intetrochanteric fossa. On 37 38 1568 the expanded distal end of the femur the substantial tibial and fibular articular condyles 39 40 1569 occupy the distal end (Fig. 19F, fi.c., ti.c.), and wrap round some distance onto the ventral 41 1570 face of the femur, a characteristic of sprawling forms. 42 43 1571 The proximal head of this femur of Shansisaurus is curved slightly anteriorly 44 45 1572 (preaxially) (Lee 1997, character 107; Tsuji 2013, character 95); the postaxial flange is 46 1573 present, and extends the entire length of the femur, but is narrower in the middle, so the femur 47 48 1574 looks concave in dorsal or ventral view (Lee 1997, character 112; Tsuji 2013, character 97); 49 50 1575 and the internal (minor) trochanter is long and curved in its proximal region in ventral view, 51 1576 with the preaxial (anterior) side concave and the postaxial (posterior) side convex (Lee 1997, 52 53 1577 character 114; Tsuji 2013, character 98). 54 55 1578 Additional undescribed limb elements are three polygonal bones that may have been 56 1579 elements of the ankle or wrist. They are part of IVPP V6722, and so presumably belong with 57 58 1580 the other elements, and yet three of them (Fig. 19G–I) cannot readily be matched with ankle 59 60 Zoological Journal of the Linnean Society Page 48 of 85

48 1 2 3 1581 or wrist elements from other pareiasaurs. The largest (Fig. 19G) is a flattened element, 4 5 1582 bearing three articular facets, two at one end, separated from each other by a narrow bone 6 1583 bridge, and set at an angle of about 90o to each other, and a single facet at the other end. This 7 8 1584 element measures 68 mm long, 70 mm wide across the double facets, and 56 mm wide at the 9 10 1585 other end. This could be identified as an astragalocalcaneum, in which the double facets were 11 1586 for contact with tibia and fibula, and the single, or broader facet at the other end, with a 12 13 1587 number of smaller distal tarsals. The second element (Fig. 19H) is 66 mm long and with 14 15 1588 terminal ends 60 mm and 50 mm wide, and is generally similar in shape. The identity of these 16 1589 two elements is uncertain: they look like the astragalus of the stem-amniote Diadectes 17 18 1590 (Schaeffer 1941: fig.For 13D), and Review very different from the rectangularOnly astragalocalcaneum, 19 20 1591 pierced with a foramen, seen in other pareiasaurs (e.g. Lee 1997: fig. 18; Tsuji 2013: fig. 7). 21 1592 The third, smaller element (Fig. 19I) is more equidimensional, with terminal facets, and a 22 23 1593 narrowed shaft between. It is 46 mm long and 45 mm and 34 mm wide across each end, and 24 25 1594 could be a distal tarsal or carpal. If correctly identified, these elements suggest 26 1595 Huanghesaurus had a fused astragalocalcaneum (Tsuji 2013, character 100; Lee, 1997, 27 28 1596 character 116), a typical feature of pareiasaurs (Lee, 1995). 29 30 1597 31 1598 32 33 1599 DERMAL ARMOUR 34 35 1600 36 1601 Osteoderms of the Chinese pareiasaurs have not been described or illustrated, but Young & 37 38 1602 Yeh (1963: 211) noted ‘There is no sure indication of the presence of the dermal scutes, 39 40 1603 although some of the fragmentary bone may be proved as such’. Gao (1983, p. 200) describes, 41 1604 but does not illustrate armour plates from Huanghesaurus. Indeed, among the un-catalogued 42 43 1605 material of Huanghesaurus (IVPP V6722), there are five armour plates (Fig. 19J), each 44 45 1606 saddle-shaped, with a smooth, convex internal face, and a sculpted external face, with a 46 1607 central boss and generally radiating sculpture. The best specimen measures 48 x 33 mm, and 47 48 1608 23 mm thick at the boss. These are similar to the armour plates of Scutosaurus (Lee, 1997, 49 50 1609 fig. 20B), but more regular in outline. Presumably these plates were set in the skin of 51 1610 Huanghesaurus in regular rows, with their long axes mediolaterally oriented, as in the 52 53 1611 reconstruction of Scutosaurus armament (Lee, 1997: fig. 19B). An extraneous rounded 54 55 1612 structure is preserved on the radius of Huanghesaurus, adhering to the bone at the distal end. 56 1613 This rounded 45 x 25 mm bony object could be interpreted as a dermal ossification of the 57 58 1614 kind seen in Anthodon, but it seems to lack internal structure. Four or five similar rounded 59 60 Page 49 of 85 Zoological Journal of the Linnean Society

49 1 2 3 1615 objects occur among the uncatalogued Huanghesaurus material (IVPP V6722) and they may 4 5 1616 be either coprolites of some smaller animal, or inorganic nodules of some kind. 6 1617 These previously undescribed armour plates allow coding of some cladistic characters, 7 8 1618 namely osteoderms present (Tsuji, 2013, character 105; Lee, 1997, character 122); dorsal 9 10 1619 surface of osteoderm possesses a distinct rounded central boss (Tsuji, 2013, character 106; 11 1620 Lee, 1997, character 123); osteoderm ornamentation consists of few, large, lumpy ridges, 12 13 1621 irregularly spaced (Tsuji, 2013, character 107; Lee, 1997, character 124); and osteoderms are 14 15 1622 round and small, no larger than the diameter of the centra of dorsal vertebrae (Tsuji, 2013, 16 1623 character 108; Lee, 1997, character 125). 17 18 1624 For Review Only 19 20 1625 21 1626 RECONSTRUCTION 22 23 1627 24 25 1628 A detailed reconstruction of Shihtienfenia is not attempted because so many portions of the 26 1629 skeleton and skull are missing. However, the articulated shoulder girdle region confirms that 27 28 1630 this pareiasaur resembled the Russian Scutosaurus closely in size and proportions, so a 29 30 1631 reconstruction is attempted (Fig. 20) based on the classic sketch reconstruction of Scutosaurus 31 1632 by Helen Ziska, reproduced in Gregory (1946), with modifications based on known elements 32 33 1633 from Shihtienfenia. Like other derived pareiasaurs, Shihtienfenia was a bulky animal, with a 34 35 1634 massive torso, powerful, sprawling limbs, and a short neck and relatively small head. The 36 1635 teeth are those of a herbivore, and the massive torso implies substantial digestive systems, 37 38 1636 also typical of herbivores. 39 40 1637 41 1638 42 43 1639 PHYLOGENETIC ANALYSIS 44 45 1640 46 1641 The aim is not to provide a new phylogenetic analysis of the pareiasaurs. Indeed, in a series of 47 48 1642 recent publications (Lee 1997; Jalil and Janvier 2005; Tsuji & Müller 2008; Tsuji 2013; Tsuji 49 50 1643 et al. 2013), with slight revisions of the data matrix, a reasonably stable phylogeny has been 51 1644 established. The aim here has been to code the Chinese pareiasaurs first-hand, perhaps for the 52 53 1645 first time, instead of simply from publications, and to do so in light of the thorough alpha- 54 55 1646 taxonomic review just performed. The major specimens were coded separately so that the 56 1647 relative positions of the synonymised taxa Shihtienfenia, Shansisaurus, and Huanghesaurus 57 58 1648 might be assessed. The data matrix of Tsuji (2013) was used, representing a substantial 59 60 Zoological Journal of the Linnean Society Page 50 of 85

50 1 2 3 1649 revision of the Lee (1997) matrix, and character codings for the four putative Chinese taxa 4 5 1650 considered here, Shihtienfenia, Shansisaurus, Huanghesaurus, and Sanchuansaurus, are 6 1651 shown in Table 4. The evidence for the codings is presented throughout the descriptive 7 8 1652 portion of the paper. Honania is not included, as the author has not seen the new material 9 10 1653 first-hand. 11 1654 The cladistic data matrix, comprising 30 taxa and 126 characters, with all characters 12 13 1655 run as unordered and equally weighted, was analysed in PAUP 4.0a146 for Macintosh (X86), 14 15 1656 using standard settings for a parsimony analysis by the branch-and-bound method. Six 16 1657 characters were parsimony uninformative, and the analysis based on the remaining 120 17 18 1658 characters retained For11340 trees Reviewof length 219 steps (consistency Only index excluding 19 20 1659 uninformative characters = 0.7170, retention index = 0.8611, rescaled consistency index = 21 1660 0.6252). The strict consensus tree (Fig. 21) was well resolved, except for some uncertainty in 22 23 1661 the relationships of the nycteroleterids in the outgroup, Provelosaurus and Nanoparia, and the 24 25 1662 three Chinese taxa Shihtienfenia, Shansisaurus, and Huanghesaurus. Bootstrap values were 26 1663 100% throughout, except for the two lower values shown (Fig. 21). 27 28 1664 The cladistic analysis confirms previous analyses in broad outline (e.g. Lee 1997; Jalil 29 30 1665 and Janvier 2005; Tsuji 2013), but differs in obtaining better resolution of the several 31 1666 outgroup taxa, from Millerettidae to Macroleter, especially in discriminating Nycteroleteridae 32 33 1667 from the other taxa, and in resolving the relationships of the basal pareiasaurs, and those of 34 35 1668 the derived clade around Pareiasaurus and Arganaceras. The analysis confirms the clades 36 1669 Pareiasauromorpha, Pareiasauria, Velosauria, Pumiliopareiasauria (Provelosaurus– 37 38 1670 Pumilopareia), Therischia, and the Pareiasuchus–Shihtienfenia subclades. The clade name 39 40 1671 Pareiasauria was erected by Seeley (1888), the names Velosauria, Therischia, and 41 1672 Pumiliopareiasauria by Lee (1994), and used first in print by deBraga and Rieppel (1997), 42 43 1673 although not by Lee (1997) himself. The clade Elginiidae was named by Cope (1896), and 44 45 1674 widely used by Russian authors in particular since then. 46 1675 This leaves unnamed the Pareiasuchus-Shihtienfenia clade, which we term here the 47 48 1676 Sinopareiasauria, referencing the Chinese pareiasaurs in this small clade. This clade has 49 50 1677 been robust in all recent cladistic analyses (e.g. Lee 1997; Jalil and Janvier 2005; Tsuji 2013), 51 1678 and yet has only a single apomorphy (character 69, 1 ! 2; scapular blade length: very long, 52 53 1679 with a length at least three times the diameter of the glenoid fossa). 54 55 1680 As for the Chinese taxa, Sanchuansaurus is clearly separated from the other three 56 1681 genera and placed in a more basal position in the cladogram (Fig. 21), between Deltavjatia 57 58 1682 and the derived Velosauria. This confirms its distinctiveness as a separate genus from the 59 60 Page 51 of 85 Zoological Journal of the Linnean Society

51 1 2 3 1683 other Chinese taxa. Importantly, the other three taxa form an unresolved tritomy paired with 4 5 1684 the two valid species of Pareiasuchus, and this strongly suggests that Shansisaurus and 6 1685 Huanghesaurus can be reasonably synonymised with Shihtienfenia, as suggested earlier in the 7 8 1686 systematic and descriptive section of this paper. 9 10 1687 The cladogram makes no indications about the palaeogeographic history of the 11 1688 pareiasaurs. Indeed, the 22 taxa divide into subclades that do not correspond to geographic 12 13 1689 regions, with African, Russian, and Chinese taxa occurring together within subclades, perhaps 14 15 1690 suggesting that many taxa were more-or-less worldwide in occurrence over the supercontinent 16 1691 Pangaea. There is an approximate stratigraphic equivalence of the cladogram, with three 17 18 1692 broad age bands represented:For MiddleReview Permian (Bradysaurus Only, Embrithosaurus, 19 20 1693 Nochelesaurus), Wuchiapingian (Deltavjatia, Pumiliopareiasauria, Pareiasuchus, 21 1694 Pareiasaurus) and Changhsingian (Sanchuansaurus, Shihtienfenia, Scutosaurus, Elginiidae). 22 23 1695 24 25 1696 CONCLUSION 26 1697 27 28 1698 The detailed redescription of the various pareiasaur fossils from the Late Permian of China 29 30 1699 has confirmed earlier suggestions that there might be only two valid taxa, Sanchuansaurus 31 1700 and Shihtienfenia in the Sunjiagou Formation. These are distinguished by several characters, 32 33 1701 especially those that place Shihtienfenia in the derived clades Velosauria and Therischia, as 34 35 1702 well as the lower number of marginal cusps in tooth crowns (9-11) in Sanchuansaurus, and 36 1703 the general points that it is of smaller size and of greater stratigraphic age. Nearly all the 37 38 1704 specimens described by Chinese authors from 1963 onwards could be examined first-hand, 39 40 1705 and these confirm the key features presented in earlier papers by Young and Yeh (1963), Gao 41 1706 (1983, 1989), Cheng (1980), and Young (1979). 42 43 1707 Phylogenetic analysis confirms that pareiasaurs are related to nycteroleterids and 44 45 1708 procolophonians, but probably not to turtles. In detail, the phylogeny broadly tracks the 46 1709 evolution of the clade through time, with origins in the Middle Permian, and substantial 47 48 1710 diversification through the Late Permian across Russia, Africa, and China, with occasional 49 50 1711 incursions into South America and western Europe. The palaeogeographic history appears to 51 1712 suggest a main centre of evolution in South Africa, and with repeated excursions of taxa 52 53 1713 worldwide happening several times. 54 55 1714 The relative completeness of the first-named Chinese pareiasaur, Shihtienfenia 56 1715 permica, suggests that complete specimens can be found in the Sunjiagou Formation. 57 58 1716 Materials collected later were less complete, and yet the individual bones appear to be 59 60 Zoological Journal of the Linnean Society Page 52 of 85

52 1 2 3 1717 generally in good condition; this suggests that the materials may have been limited as much 4 5 1718 for logistical reasons as taphonomic. Therefore, complete skeletons, as found in Russia and 6 1719 South Africa, may await an expedition with sufficient lifting and transporting equipment. 7 8 1720 9 10 1721 ACKNOWLEDGEMENTS 11 1722 12 13 1723 I am very grateful to the Chinese Academy of Sciences for funding my visit to China in April 14 15 1724 and May 2012 as a CAS Visiting Professor, and to Fucheng Zhang for arranging the 16 1725 application. At the Institute of Vertebrate Paleontology and Paleoanthropology, I am grateful 17 18 1726 to Jun Liu for adviceFor and conversations Review about Chinese PermianOnly tetrapods, to Zheng Fang for 19 20 1727 making the IVPP collections available and helping in manhandling unwieldy specimens, and 21 1728 to my PhD student Qi Zhao for making daily arrangements and for teaching me some 22 23 1729 Chinese. Further, I thank Mike Lee and an anonymous referee for many helpful comments 24 25 1730 that helped restructure the paper. 26 1731 27 28 1732 29 30 1733 REFERENCES 31 1734 32 33 1735 Apesteguía S. 2005. Evolution of the hyposphene–hypantrum complex within Sauropoda. In: 34 35 1736 Tidwell V, Carpenter, K, eds. Thunder-lizards: the sauropodomorph dinosaurs. 36 1737 Bloomington: University of Indiana Press, Bloomington, 248–267. 37 38 1738 Araújo DCF. 1985. Sobre Pareiasaurus americanus sp. nov., do Permiano Superior do Rio 39 40 1739 Grande do Sul, Brasil. I. Diagnose especifica. Anais Academie do Brasileira de Ciências 41 1740 57: 63–66. 42 43 1741 Benton MJ. 2012. No gap in the Middle Permian record of fossil vertebrates. Geology 40: 44 45 1742 339-342. 46 1743 Benton MJ, Newell AJ, Khlyupin AYu, Shumov IS, Price GD, Kurkin AA. 2012. 47 48 1744 Preservation of exceptional vertebrate assemblages in Middle Permian fluviolacustrine 49 50 1745 mudstones of Kotel'nich, Russia: stratigraphy, sedimentology, and taphonomy. 51 1746 Palaeogeography, Palaeoclimatology, Palaeoecology 319-320: 58-83. 52 53 1747 Canoville A, Thomas DB, Chinsamy A. 2014. Insights into the habitat of Middle Permian 54 55 1748 pareiasaurs (Parareptilia) from preliminary isotopic analyses. Lethaia 47: 266–274. 56 1749 Cheng ZW. 1980. Mesozoic stratigraphy and paleontology of the Shaanxi-Gansu-Ningxia 57 58 1750 Basin. Vol. 2. Beijing: Publishing House of Geology, 115-119. [In Chinese.] 59 60 Page 53 of 85 Zoological Journal of the Linnean Society

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56 1 2 3 1848 Tsuji LA. 2013. Anatomy, cranial ontogeny and phylogenetic relationships of the pareiasaur 4 5 1849 Deltavjatia rossicus from the Late Permian of central Russia. Earth & Environmental 6 1850 Science Transactions of the Royal Society of Edinburgh 104: 81–122. 7 8 1851 Tsuji LA, Müller J. 2008. A reevaluation of Parasaurus geinitzi, the first named pareiasaur 9 10 1852 (Amniota, Parareptilia). Canadian Journal of Earth Sciences 45: 1111–1121. 11 1853 Tsuji LA. Sidor CA, Steyer JS, Smith RMH, Tabor NL, Ide O. 2013. The vertebrate fauna 12 13 1854 of the Upper Permian of Niger–VII. Cranial anatomy and relationhips of Bunostegos 14 15 1855 akokanensis (Pareiasauruia). Journal of Vertebrate Paleontology 33: 747–763. 16 1856 Vickaryous MK, Hall BK. 2006. Homology of the reptilian coracoid and a reappraisal of the 17 18 1857 evolution and developmentFor Review of the amniote pectoral Onlyapparatus. Journal of Anatomy 208: 19 20 1858 263-285. 21 1859 Wang ZQ. 1993. Evolutionary ecosystem of Permian-Triassic redbeds in North China: a 22 23 1860 historical record of global desertification. In: Lucas, SG, Morales, M, eds. The 24 25 1861 Nonmarine Triassic. Albuquerque: New Mexico Museum of Natural History & Science, 26 1862 471-476. 27 28 1863 Wang ZQ, Chen AS. 2001. Traces of arborescent lycopsids and dieback of the forest 29 30 1864 vegetation in relation to the terminal Permian mass extinction in North China. Review of 31 1865 Palaeobotany and Palynology 117: 217–243. 32 33 1866 Wang ZQ, Wang LX. 1986. Late Permian fossil plants from the lower part of the 34 35 1867 Shiqeunfeng (Shihshoenfeng) group in North China. Bulletin of the Tianjin Institute of 36 1868 Geology and Mineral Resources 15: 1–80 [in Chinese with English abstract]. 37 38 1869 Xu L, Li XW, Jia SH, Liu J. 2015. The Jiyaun tetrapod fauna of the Upper Permian of 39 40 1870 China. New pareiasaur material and the reestablishment of Honania complicidentata. 41 1871 Acta Palaeontologica Polonica 60: 689-700. 42 43 1872 Young CC. 1979. A Late Permian fauna from Jiyuan, Henan. Vertebrata PalAsiatica 1979: 44 45 1873 17: 99-113. [In Chinese.] 46 1874 Young CC, Yeh HK. 1983. On a new pareiasaur from the Upper Permian of Shansi, China. 47 48 1875 Vertebrata PalAsiatica 17: 195–214. 49 50 1876 Zhang Y, Zheng SL, Naugolnykh SV. 2012. A new species of Lepidopteris discovered from 51 1877 the Upper Permian of China with its stratigraphic and biologic implications. Chinese 52 53 1878 Science Bulletin 57: 3603–3609. 54 55 1879 56 57 58 59 60 Page 57 of 85 Zoological Journal of the Linnean Society

57 1 2 3 1880 Figure 1. Locality map of western Shanxi Province, showing the principal pareiasaur 4 5 1881 localities, at Baode, on the banks of the Yellow River, and at Xuecun, and other localities in 6 1882 Liujin, on the Sanchuan River. The base map (from Google Maps) shows topography and 7 8 1883 main roads and towns, and the Lower and Middle-Upper Permian (LP, M-UP) outcrop, is 9 10 1884 marked, showing continuity of occurrences in the Upper Permian from Baode to Luliang. 11 1885 12 13 1886 Figure 2. Summary stratigraphic chart of the Middle and Late Permian, showing the 14 15 1887 international marine stratigraphic epochs and stages, the magnetostratigraphic pattern and key 16 1888 zones, the Russian stages, gorizonts, tetrapod zones, and faunal complexes, the South Afican 17 18 1889 tetrapod assemblageFor zones, and Review the North Chinese formations Only and tetrapod faunas. The 19 20 1890 outlines of the diagram are from Benton (2012) and Benton et al. (2013), with revisions of the 21 1891 Karoo boundaries, and radiometric dates (indicated by solid circles) from Rubidge et al. 22 23 1892 (2012). The Chinese horizons and correlations are discussed in the text, and are based mainly 24 25 1893 on Stevens et al. (2011). 26 1894 27 28 1895 Figure 3. Teeth of Honania complicidentata Young, 1979. A, Isolated tooth, IVPP V4015.1. 29 30 1896 B, Isolated tooth, IVPP V4015.3. C, Original image from Young (1979, fig. 4), showing the 31 1897 Honania type series, teeth IVPP V4015.1 (two views), V4015.2, and V4015.3 (two views). D, 32 33 1898 Original image from Young (1979, fig. 5), showing the Tsiyuania type series, teeth IVPP 34 35 1899 V4016.1 (two views) and V4016.2 (two views). Abbreviation: ci, cingulum. 36 1900 37 38 1901 Figure 4. Right maxilla of Sanchuansaurus pygmaeus Gao, 1989 (IVPP V6723), in lateral 39 40 1902 (A), medial (B), and dorsal (C) views. Abbreviations: a.p., antorbital process; io.c., 41 1903 infraorbital canal; p.s., palatal shelf; 1–15, tooth numbers. 42 43 1904 44 45 1905 Figure 5. Hindlimb elements of Sanchuansaurus pygmaeus Gao, 1989. (A–D) left femur 46 1906 (IVPP V6724), in dorsal (A), posterior (B), ventral (C), and anterior (D) views. (E–H) left 47 48 1907 fibula (IVPP V6725) in dorsal (E), posterior (F), ventral (G), and anterior (H) views. 49 50 1908 Abbreviations: a.t., anterior trochanter; fib., facet for articulation with fibulare; fi.c., fibular 51 1909 condyle of femur; int., facet for articulation with intermedium; i.s., intercondylar sulcus; p.f., 52 53 1910 posterior flange; ti.c., tibial condyle of femur. 54 55 1911 56 1912 Figure 6. Putative left jugal (IVPP V6722-3) of Shihtienfenia permica Young and Yeh, 1963, 57 58 1913 originally ascribed to Huanghesaurus, in lateral (A) and medial (B) views. 59 60 Zoological Journal of the Linnean Society Page 58 of 85

58 1 2 3 1914 4 5 1915 6 1916 Figure 8. Mandible elements of Shihtienfenia permica Young and Yeh, 1963, originally 7 8 1917 ascribed to Huanghesaurus. (A, B) portion of left dentary (IVPP unnumbered) in lateral (A) 9 10 1918 and medial (B) views. (C–E) details of the dentary dentition (IVPP V6722-1) in lateral (C) 11 1919 and medial (D) views, and close-up of dentary teeth 11 and 12 (E). Abbreviations: ci, 12 13 1920 cingulum; ri, ridge. 14 15 1921 16 1922 Figure 9. Posterior cervical vertebrae of Shihtienfenia permica Young and Yeh, 1963. (A) 17 18 1923 Posterior cervical vertebraFor (IVPP Review V2717) in anterior view. Only (B) Posterior cervical vertebrae, , 19 20 1924 originally ascribed to Huanghesaurus (IVPP V6722-4 to 7), in lateral view. Abbreviations: 21 1925 ce., centrum; dp., diapophysis; n.a., neural arch; n.c., neural canal; n.sp., neural spine; poz., 22 23 1926 postzygapophysis; pp., parapophysis; prz., prezygapophysis; t.p., transverse process. 24 25 1927 26 1928 Figure 10. Posterior dorsal vertebrae of Shihtienfenia permica Young and Yeh, 1963. (A–C) 27 28 1929 Posterior dorsal vertebrae (IVPP V2717; presacrals 16-20?) in dorsal (A~), left lateral (B), 29 30 1930 and ventral (C) views. Abbreviations: n.c., neural canal; n.sp., neural spine; poz., 31 1931 postzygapophysis; prz., prezygapophysis; t.p., transverse process; 16–20, estimated numbers 32 33 1932 of dorsal vertebrae. 34 35 1933 36 1934 Figure 11. Sacral vertebrae and first caudal vertebra of Shihtienfenia permica Young and 37 38 1935 Yeh, 1963 (IVPP V2717), in right lateral (A), left lateral (B), near-dorsal (C(), and ventral (D) 39 40 1936 views. Abbreviations: ca.v.1, caudal vertebra 1; n.sp., neural spine; poz., postzygapophysis; 41 1937 prz., prezygapophysis; s.r.1, sacral rib 1; 1–5, sacral vertebrae 1–5. 42 43 1938 44 45 1939 Figure 12. Isolated ribs of Shihtienfenia permica Young and Yeh, 1963, originally ascribed to 46 1940 Huanghesaurus, in lateral (above) and medial (below) views. (A) cervical rib (IVPP V6722- 47 48 1941 18), (B, C) anterior dorsal ribs (IVPP V6722-20, 21), and (D) mid-dorsal rib (IVPP V6722- 49 50 1942 22). Abbreviations: ca., capitulum; tu., tuberculum). 51 1943 52 53 1944 Figure 13. Right scapula of Shihtienfenia permica Young and Yeh, 1963 (IVPP V2717), in 54 55 1945 lateral (A), anterior (B), medial (C) and posterior (D) views. Abbreviations: acr., acromion 56 1946 process; gl., glenoid; int.pr., internal process. 57 58 1947 59 60 Page 59 of 85 Zoological Journal of the Linnean Society

59 1 2 3 1948 Figure 14. Left shoulder girdle of Shihtienfenia permica Young and Yeh, 1963 (IVPP 4 5 1949 V2717), in lateral (A) and medial (B) views, comprising scapula, coracoid, and clavicle, 6 1950 partly held together by a metal armature used when the specimen was displayed in the IVPP 7 8 1951 public museum. Abbreviations: acr., acromion process; cl., clavicle; co., coracoid; co.f., 9 10 1952 coracoid foramen; gl., glenoid; sc., scapula. 11 1953 12 13 1954 Figure 15. Various scapulocoracoid remains of Shihtienfenia permica Young and Yeh, 1963. 14 15 1955 (A–D) Left scapulocoracoid, originally ascribed to Huanghesaurus (IVPP V6722-22), in 16 1956 lateral (A, B) and medial (C, D) views, showing ths specimen and a sketch interpretation. (E, 17 18 1957 F) Left scapulocoracoidFor originally Review assigned to Shansisaurus Only sp. (IVPP V6727), in lateral (E) 19 20 1958 and medial (F) views. (G, H) Left scapula originally assigned to ‘Pareiasauride sp.’ (IVPP 21 1959 V8533), in lateral (E) and medial (F) views. Abbreviations: aco., anterior coracoid; acr., 22 23 1960 acromion process; co.f., coracoid foramen; gl., glenoid; pco., posterior coracoid; pr., process; 24 25 1961 sc., scapula; s.s.f., subscapular fossa. 26 1962 27 28 1963 Figure 16. Dermal shoulder girdle of Shihtienfenia permica Young and Yeh, 1963. (A) Left 29 30 1964 side of shoulder girdle (IVPP V2717), showing clavicle in place. (B–E) Right and left 31 1965 clavicles originally ascribed to Huanghesaurus (IVPP V6722-22) in anterior (B), external (C), 32 33 1966 posterior (D), and internal (E) views. (F, G) Interclavicle originally ascribed to 34 35 1967 Huanghesaurus (IVPP V6722-22) in external/ ventral (F) and internal/ dorsal (G) views, the 36 1968 latter showing the proximal part of the left clavicle in position. (H, I) Sketch reconstructions 37 38 1969 of the shoulder girdle of IVPP V2717, and anterior (H) and left lateral (I) views. 39 40 1970 Abbreviations: cl., clavicle; cl.f., clavicular facet; co., coracoid; h, humerus; icl,pr., 41 1971 interclavicle process; p.fl., posterior flange; p.pr., posterior process; R, right-hand side; sc., 42 43 1972 scapula. 44 45 1973 46 1974 Figure 17. Humerus of Shihtienfenia permica Young and Yeh, 1963. (A–D) Left humerus of 47 48 1975 Shihtienfenia (IVPP V2717) in ventral (A), anterior (B), dorsal (C), and posterior (D) views. 49 50 1976 (E, F) Left humerus of Huanghesaurus (IVPP V6722-26) in dorsal (E) and ventral (F) views. 51 1977 (G) Left humerus of ‘Pareiasauridae indet.’ (IVPP V8534) in ventral view. Abbreviations: 52 53 1978 a.d.v.l., anterior dorso-ventral line; a.f., articular facet; dpc, deltopectoral crest; ect., 54 55 1979 ectepicondyle; ent, entepicondyle; ent.f., entepicondylar foramen; ic.f., intercondylar fossa; 56 1980 p.a.f., posterior articular facet; sup., supinator process. 57 58 1981 59 60 Zoological Journal of the Linnean Society Page 60 of 85

60 1 2 3 1982 Figure 18. Ulna and radius of Shihtienfenia permica Young and Yeh, 1963. (A. B) Left ulna 4 5 1983 of Huanghesaurus (IVPP V6722-27) in lateral (A) and medial (B) views. (C, D) Left radius 6 1984 of Huanghesaurus (IVPP V6722-28) om lateral (C) and medial (D) views. Abbreviations: 7 8 1985 ole., olecranon; sig.n., sigmoid notch; sig. p., sigmoid process. 9 10 1986 11 1987 Figure 19. Pelvis and hindlimb of Shihtienfenia permica Young and Yeh, 1963. (A, B) Left 12 13 1988 side of pelvis of Shihtienfenis (IVPP V2727), in lateral (A) and medial (B) views. (C, D) 14 15 1989 Right side of pelvis of Shihtienfenis (IVPP V2727), in lateral (C) and medial (D) views. (E, F) 16 1990 Left femur of Shansisaurus (CAGS V301), in dorsal (E) and ventral (B) views. (G–H) Ankle 17 18 1991 bones of HuanghesaurusFor (IVPP Review V6722): possible astragalocalcaneum Only (G), unidentified ankle 19 20 1992 bone (H), and possible tarsal or carpal (I). (J) Dermal plates of Huanghesaurus (IVPP 21 1993 V6722). Abbreviations: ac., acetabulum; ant.pr., anterior process; cr.sac., crista sacralis; fi.c., 22 23 1994 fibular condyle; i.tr., internal trochanter; ic.f., intercondylar foramen; il., ilium; is., ischium; 24 25 1995 pu., pubis; sa.r.4, sacral rib 4; ti.c., tibial condyle; tr.m., trochanter major. 26 1996 27 28 1997 Figure 20. Reconstruction of Shihtienfenia permica Young and Yeh, 1963, based on 29 30 1998 preserved elements, photographs of the whole-skeleton mount (Young and Yeh 1963, pls. 1, 31 1999 2), and broad comparability with Scutosaurus, as reconstructed in Ziska in Gregory (1946). 32 33 2000 34 35 2001 Figure 21. Strict consensus cladogram of relationships among pareiasaurs, with the four 36 2002 named Chinese taxa highlighted in bold. Bootstrap values are 100% throughout, except for 37 38 2003 the two values shown (51%, 52%). 39 40 2004 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 61 of 85 Zoological Journal of the Linnean Society

61 1 2 3 2005 Table 1. Basic measurements of the crowns of Chinese pareiasaur teeth. Explanation of 4 5 2006 measurements: breadth, maximum anteroposterior width of the crown, measured on the 6 2007 medial (lingual) face, in mm; height, maximum dorsoventral measurement from tooth tip to 7 8 2008 cenre of cingulum, measured on medial (lingual) face, in mm; cingulum and marginal 9 10 2009 denticles represent totals. Position in tooth row is indicated for teeth of Sanchuansaurus and 11 2010 Huanghesaurus, in parentheses after the repository number; abbreviation: R, replacement. 12 13 2011 14 15 2012 Cingulum Marginal 16 2013 Genus Specimen Height Breadth denticles denticles 17 18 2014 Honania IVPPFor V4015.1 Review 13 10 Only c. 12 16 19 20 2015 Honania IVPP V4015.2 - 10 - 15-17 21 2016 Honania IVPP V4015.3 11.5 9.5 c. 12 12-14 22 23 2017 Tsiyuania IVPP V4016.1 13.5+ 14 c. 15 8+ 24 25 2018 Tsiyuania IVPP V4016.2 12+ 12+ - - 26 2019 Sanchuansaurus IVPP V6723 (4) 5.5 8 10-12 c. 10 27 28 2020 Sanchuansaurus IVPP V6723 (7) c. 8 9 10-12 9-10 29 30 2021 Sanchuansaurus IVPP V6723 (8R) 9 c. 9 - c. 10 31 2022 Sanchuansaurus IVPP V6723 (9) 8.5 9 10-12 c. 10 32 33 2023 Sanchuansaurus IVPP V6723 (11) 8+ 10 10-12 c. 9 34 35 2024 Sanchuansaurus IVPP V6723 (13) 10+ 11 c. 12 c. 10 36 2025 Huanghesaurus IVPP V6722-1 (1) 12.5+ c. 12 - - 37 38 2026 Huanghesaurus IVPP V6722-1 (3) 14 12 - 15-16 39 40 2027 Huanghesaurus IVPP V6722-1 (5) 19 12 5-6 15-16 41 2028 Huanghesaurus IVPP V6722-1 (10) 15 11-12 5-6 15-17 42 43 2029 Huanghesaurus IVPP V6722-1 (12) 14 12 5-6 13-15 44 45 2030 46 2031 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Zoological Journal of the Linnean Society Page 62 of 85

62 1 2 3 2032 Table 2. Measurements of the vertebrae of Shihtienfenia (IVPP V2717). Individual specimens 4 5 2033 are not numbered separately, so references to figures in Yang and Yeh (1963) are given, 6 2034 together with their identifications. 7 8 2035 1. Height from base of centrum in posterior view to top of neural spine. 9 10 2036 2. Maximum width across distal tips of transverse processes. 11 2037 3. Height of anterior articular face of centrum 12 13 2038 4. Width of anterior articular face of centrum 14 15 2039 5. Height of posterior articular face of centrum 16 2040 6. Width of posterior articular face of centrum 17 18 2041 7. Maximum lengthFor of centrum Review from anterior to posterior Only face. 19 20 2042 21 2043 22 23 2044 Number Identity 1 2 3 4 5 6 7 24 25 2045 Fig. 5, lower left Posterior cervical - ?280 90 74 110 70 82 26 2046 Fig. 5, upper left ?Presacral 11 - 230 c. 130 75 c. 130 c. 70 90 27 28 2047 Fig. 5, upper left ?Presacral 12 - 230 c. 130 c. 75 c. 120 - 90 29 30 2048 Fig. 5, upper right ?Presacral 13 - - c. 110 c. 65 - - 80 31 2049 Fig. 5, upper right ?Presacral 14 - c. 220 c. 95 c. 70 - - c.70 32 33 2050 Fig. 2. ?Presacral 16 - 190 77 105 - - 88 34 35 2051 Fig. 2. ?Presacral 17 - 220 - - - - 90 36 2052 Fig. 2. ?Presacral 18 - 220 - - - - 90 37 38 2053 Fig. 2. ?Presacral 19 - 220 - - - - 95 39 40 2054 Fig. 2. ?Presacral 20 ------41 2055 Fig. 3. Sacral 1 - c. 170 - - - - - 42 43 2056 Fig. 3. Sacral 2 c. 240 c. 160 - c. 65 - - 85 44 45 2057 Fig. 3. Sacral 3 180+ c. 180 - - - - 85 46 2058 Fig. 3. Sacral 4 180+ c. 170 - - - - 87 47 48 2059 Fig. 3. Sacral 5 - c. 130 - - - - 87 49 50 2060 Fig. 3. Caudal 1 - c. 100 - - - c. 55 c.80 51 2061 52 53 2062 54 55 56 57 58 59 60 Page 63 of 85 Zoological Journal of the Linnean Society

63 1 2 3 2063 Table 3. Measurements of the vertebrae of Huanghesaurus (IVPP V6722). 4 5 2064 1. Height from base of centrum in posterior view to top of neural spine. 6 2065 2. Maximum width across distal tips of transverse processes. 7 8 2066 3. Height of anterior articular face of centrum 9 10 2067 4. Width of anterior articular face of centrum 11 2068 5. Height of posterior articular face of centrum 12 13 2069 6. Width of posterior articular face of centrum 14 15 2070 7. Maximum length of centrum from anterior to posterior face. 16 2071 17 18 2072 For Review Only 19 20 2073 Number Identity 1 2 3 4 5 6 7 21 2074 IVPP V6722-4 Posterior cervical - - - - 87 72 80 22 23 2075 IVPP V6722-5 Posterior cervical - - 78 c. 75 80 82 80 24 25 2076 IVPP V6722-6 Posterior cervical 200 - c. 90 82 90 90 80 26 2077 IVPP V6722-7 Posterior cervical 220 c. 140 - - c. 95 - c.75 27 28 2078 IVPP V6722-8 Posterior dorsal 265 245 110 115 95 110 65 29 30 2079 IVPP V6722-9 Posterior dorsal - - 110 110 95 110 60 31 2080 IVPP V6722-10 Posterior dorsal 32 33 2081 IVPP V6722-11 Posterior dorsal - - 110 105 - - - 34 35 2082 IVPP V6722-12 *Posterior dorsal - - 90 77 98 85 64 36 2083 IVPP V6722-13 *Posterior dorsal 322 - 95 70 90 70 80 37 38 2084 IVPP V6722-14 Posterior dorsal - - 117 102 94 102 62 39 40 2085 IVPP V6722-15 Posterior dorsal 293 255 90 86 85 80 58 41 2086 IVPP V6722-16 Posterior dorsal - 252 - - - - - 42 43 2087 *crushed and distorted 44 45 2088 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Zoological Journal of the Linnean Society Page 64 of 85

64 1 2 3 2089 Table 4. Character codings for the Chinese pareiasaurs, listed according to the original 4 5 2090 designations of the taxa. Character numbering follows Lee (1997) and Tsuji (2013). Character 6 2091 absences are coded ‘?’. 7 8 2092 9 2093 Taxon Character number 10 2094 11 11-11 1-1—1 12222 22333 33-33 44444 11 2095 [Lee 1997] 23456 78901 23-45 6-7-- 89013 56012 36-78 13567 12 13 2096 1 11111 11112 22222 22223 33333 33334 14 2097 [Tsuji 2013] 12345 67890 12345 67890 12345 67890 12345 67890 15 2098 Shihtienfenia ????? ????? ????? ????? ????? ????? ????? ????? 16 2099 Shansisaurus ????? ????? ????? ????? ????? ????? ????? ????? 17 2100 Huanghesaurus ????? ????? ????? ????? ????? ????? ????? ????? 18 2101 Sanchuansaurus For ?????Review ????? ????? ????? Only????1 1???? ????? ????? 19 2102 20 2103 ---4- 555-2 55656 66666 -6977 77777 78888 88888 21 2104 [Lee 1997] ---9- 124-7 58190 34567 -8301 23457 91234 56789 22 2105 44444 44445 55555 55556 66666 66667 77777 77778 23 2106 [Tsuji 2013] 12345 67890 12345 67890 12345 67890 12345 67890 24 2107 Shihtienfenia ????? ????? ????? ????? ?03?? ??120 11111 11011 25 26 2108 Shansisaurus ????? ????? ????? ????? ????? ??120 1???? ????? 27 2109 Huanghesaurus ? ? ? ? ? 1 110? ?11?4 11??? ?0??? ??120 11111 01??? 28 2110 Sanchuansaurus ????? ????1 0113? ?1??? ????? ????? ????? ????? 29 2111 30 2112 1 11111 11111 11111 11111 1------31 2113 99999 99990 00000 01111 11222 22222 2------32 2114 [Lee 1997] 01245 67890 13457 92456 89012 34567 8------33 2115 1 11111 11111 11111 11111 34 2116 88888 88889 99999 99990 00000 00001 11111 11112 35 2117 [Tsuji 2013] 12345 67890 12345 67890 12345 67890 12345 67890 36 2118 Shihtienfenia 0??01 11211 0???? ????? ????? ????? ????? ????1 37 38 2119 Shansisaurus ????? ????? ????1 111?? ????? ????? ????? ????? 39 2120 Huanghesaurus ?0??? ????? ????? ????1 ????1 120?? ????? ????? 40 2121 Sanchuansaurus ????? ????? ????1 ?1??? ????? ????? ????? ????1 41 2122 42 2123 ------43 2124 ------44 2125 [Lee 1997] ------45 2126 11111 1 46 2127 22222 2 47 2128 [Tsuji 2013] 12345 6 48 2129 Shihtienfenia ? ? ? ? ? ? 49 2130 Shansisaurus ????? ? 50 51 2131 Huanghesaurus ? ? ? ? ? ? 52 2132 Sanchuansaurus ????? ? 53 2133 54 55 56 57 58 59 60 Page 65 of 85 Zoological Journal of the Linnean Society

1 M-UP 2 LP 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 For Review Only 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

20 km Sanchuan River

M-UP LP Zoological Journal of the Linnean Society Page 66 of 85

1 2 3 4 5 Inter- Russian Russian South African North Chinese 6 Mag. Russian Russian North Chinese national Mag. tetrapod faunal tetrapod tetrapod 7 stage stages gorizonts formations Epoch stages zones complexes assemblage zones faunas 8 Myr R P Archosaurus Vyazniki U Huanghesaurus 9 Chang. 3 rossicus Sunjiagou M Shihtienfenia 10 Dicynodon L Sanchuansaurus Vyatkian 11 Scutosaurus Sokolki 255 karpinskii 12 N2P 13 For ReviewCistecephalus OnlyJiyuan Fauna Proelginia permiana 14 Lopingian Il’inskoye Tropidostoma 15

16 Wuchiapingian R2P Sokolki Deltavjatia vjatkensis Kotel’nich 17 Tatarian Pristerognathus Shangshihezhi/ 260 Upper 18 Shihhotse 19 Severodvinian Illawarra Ulemosaurus Isheevo/ 20 Tapinocephalus 21 svijagensis Malaya Kinel

22 Capitanian N1P 23 265 Middle Upper L.

24 Guadalupian Urzhumian 25 R P Estemmenosuchus Ocher Eodicynodon 26 Wordian 1 uralensis Xiashihezhi/ Dashankou 27 Lower Fauna Biarmian 28 270 Ocher Shihhotse 29 Parabradysaurus Golyusher- Roadian Kazanian silantjevi ma 30 31 Kiama 32 Ufimian Clamorosaurus Inta nocturnus 33 Shanxi 34 275 Kungurian ‘Kungurian’ Cisuralian 35 Cisuralian 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 67 of 85 Zoological Journal of the Linnean Society

1 2 3 4 A B 5 6 7 8 9 10 11 12 13 14 ci 15 16 17 18 For Review Only 19 20 21 22 23 24 25 26 27 5 mm 28 29 30 C 31 32 33 34 35 36 37 38 39 40 41 42 D 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Zoological Journal of the Linnean Society Page 68 of 85

1 a.p. 2 A 3 4 A 5 io.c. 6 7 8 9 10 11 12 13 14 15 16 17 18 For Review Only 19 20 21 22 23 3 24 5 25 13 9 7 26 27 a.p. 28 B 29 10 mm 30 31 io.c. 32 33 34 35 36 37 p.s. 38 39 40 1 41 42 43 44 45 46 13 47 3 48 5 7 9 49 p.s. 50 C 51 52 53 54 55 56 2 57 13 58 3 5 7 9 59 60 Page 69 of 85 Zoological Journal of the Linnean Society

1 2 3 4 A B C D 5 6 7 8 9 10 11 p.f. 12 13 14 15 16 17 18 For Review Only 19 20 21 i.s. 22 23 24 fi.c. 25 26 ti.c. 27 50 mm 28 29 30 31 32 E F G H 33 34 35 36 37 a.t. 38 39 40 41 42 43 44 45 46 47 48 49 50 51 fib. int. 52 53 54 55 56 57 58 59 60 Zoological Journal of the Linnean Society Page 70 of 85

1 2 3 4 5 6 7 8 9 10 11 12 A B 13 20 mm 14 15 16 17 18 For Review Only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 71 of 85 Zoological Journal of15 the Linnean13 Society 11 9 7 1 A 5 2 3 3 4 5 sa? 6 7 8 9 10 11 12 13 14 15 an. ma.f. 16 v.o. 17 13 15 18 9 11 20 mm 19 B 5 7 20 3 21 22 pa? 23 24 25 sy. 26 27 For Review Only 28 29 30 an. 31 32 me.f. 33 d.l. 34 35 7 9 13 15 36 5 11 17 19 37 C 3 38 39 40 41 42 ar. 43 44 45 46 47 48 49 50 D E 51 52 53 54 55 me.f. 56 57 58 59 60 Zoological Journal of the Linnean Society Page 72 of 85

1 2 3 A 4 5 20 mm 6 7 8 9 10 11 B 12 13 14 15 16 17 18 19 20 21 22 23 24 25 C 13 26 15 9 7 5 27 28 11 29 30 31 For Review Only 32 33 34 35 36 3 37 38 39 40 41 42 43 44 E 45 ri 46 47 48 49 50 51 52 53 54 20 mm 55 ci 56 10 mm 57 58 59 60 13 15 9 11 7 5 D

3 Page 73 of 85 Zoological Journal of the Linnean Society

1 2 n.a. 3 n.sp. 4 B 5 A prz. 6 7 poz. 8 9 10 prz. 11 12 13 14 15 16 17 ce. 18 t.p. dp. 19 20 21 pp. 22 20 mm 23 24 25 t.p. 26 For Review Only n.sp. 27 dp. 28 C D E F prz. 29 n.sp. 30 31 32 pp. 33 34 35 36 37 n.c. 38 39 40 41 42 t.p. 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Zoological Journal of the Linnean Society Page 74 of 85

1 2 A D n.sp. 3 4 5 6 7 8 9 poz. 10 11 12 13 14 15 16 t.p. 17 t.p. poz. 18 19 20 prz. 21 22 B poz. prz. 23 n.c. 24 t.p. 25 For Review Only 26 27 28 29 poz. 30 20 31 20 mm prz. 32 33 34 35 E 36 19 37 38 16 17 r.f. 39 40 18 41 F 42 C n.sp. 43 44 45 46 47 48 49 50 51 t.p. poz. 52 53 54 t.p. 55 56 57 58 n.c. 59 60 Page 75 of 85 Zoological Journal of the Linnean Society

1 n.sp. 2 A 3 4 ca.v.1 5 20 mm 6 7 8 prz. 9 10 11 12 13 14 15 4 5 16 3 17 prz. 18 19 n.sp. 20 2 21 s.r.1 22 23 24 25 For Review Only 26 B 27 28 29 30 31 ca.v.1 32 4 3 33 5 34 5 2 35 C 2 4 36 3 37 38 39 40 41 ca.v.1 42 43 44 45 poz. 46 47 48 2 49 50 3 51 52 53 54 55 56 57 58 D 59 60 ca.v.1 5 4

s.r.1 Zoological Journal of the Linnean Society Page 76 of 85

1 2 ca. 3 tu. 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 A For BReviewC Only D 26 27 28 29 ca. tu. 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 20 mm 51 52 53 54 55 56 57 58 59 60 Page 77 of 85 Zoological Journal of the Linnean Society

1 2 3 A B C D 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 For Review Only 26 27 28 29 30 31 32 33 34 35 36 37 38 39 int.pr. 40 41 42 43 int.pr. 44 45 46 47 48 49 50 acr. 51 52 53 acr. 54 55 20 mm gl. 56 57 58 gl. gl. 59 60 Zoological Journal of the Linnean Society Page 78 of 85

1 2 3 4 A B 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 20 mm 21 22 23 24 25 For Review Only 26 27 28 29 30 31 32 33 34 35 36 37 sc. 38 39 sc. 40 41 gl. 42 cl. 43 44 co. 45 co. 46 47 48 49 50 cl. 51 52 53 54 55 co.f. 56 57 58 59 60 Page 79 of 85 Zoological Journal of the Linnean Society

1 2 3 A 40 mm C 4 5 6 7 8 9 10 B D 11 12 13 14 15 16 17 18 19 20 21 22 23 sc. sc. 24 25 For Review Only 26 27 28 29 30 31 32 33 34 acr. 35 36 acr. 37 38 co.f. 39 40 41 42 43 co.f. 44 aco. 45 pco. 46 aco. pco. 47 48 49 50 51 E F 40 mm 52 53 G 54 55 56 H 57 acr. 58 sc. acr. s.s.f. 59 60 sc. pr.

20 mm aco. co.f. aco. co.f. Zoological Journal of the Linnean Society Page 80 of 85

1 2 3 A B C 4 sc. 5 6 7 8 9 40 mm 10 11 12 13 R. R. 14 15 16 17 18 19 20 21 cl. 22 23 24 25 For Review Only 26 27 28 29 D icl.pr. E 30 31 co. 32 33 34 35 36 F cl.f. 37 38 R. R. 39 40 41 42 43 p.pr. p.fl. 44 45 46 47 48 49 50 51 G 52 53 54 55 56 H I 57 58 p.pr. sc. sc. 59 60 80 mm cl. co. cl.

h. co. h. Page 81 of 85 Zoological Journal of the Linnean Society

1 2 A C 3 4 dpc. 20 mm 5 6 dpc. 7 8 9 a.f. 10 B a.f. 11 12 13 14 15 16 D 17 18 19 20 21 22 dpc. 23 24 25 For Review Only 26 27 ect. 28 a.f. 29 30 31 32 33 34 ent. 35 36 37 ect. 38 39 40 41 42 sup. 43 ent. 44 45 46 47 ect. 48 49 a.d.v.l. 50 51 52 53 54 55 56 57 p.a.f. 58 p.a.f. 59 60

dpc. dpc. 40 mm dpc. sup. ent.f. ect. E F G ic.f ic.f Zoological Journal of the Linnean Society Page 82 of 85

1 ole. ole. 2 3 A B 4 5 C D 6 7 sig.p. 8 9 10 11 12 sig.n. 13 14 15 16 17 18 19 20 21 22 23 24 40 mm 25 For Review Only 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 83 of 85 Zoological Journal of the Linnean Society

1 ant.pr. ant.pr. ant.pr. 2 3 A B 4 5 cr.sac. 6 7 8 sa.r.4 9 10 11 12 13 14 C 15 16 17 18 ac. 19 40 mm 20 21 22 23 il. 24 25 For Review Only 26 27 28 ant.pr. 29 30 ac. 31 32 is. 33 34 35 36 37 pu. 38 39 40 41 D 42 E F 43 44 i.tr. 45 46 G H I 47 48 tr.m. 49 50 51 52 53 54 55 56 ic.f. 20 mm 57 58 59 60 ti.c. fi.c. J Zoological Journal of the Linnean Society Page 84 of 85

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 For Review Only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 100 mm 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 85 of 85 Zoological Journal of the Linnean Society Millerettidae

1 Rhipaeosaurus 2 3 Owenetta 4 5 Bashkyroleter bashkyricus 6 NYCTEROLETERIDAE 7 Nycteroleter 8 9 Bashyroleter mesensis 10 11 PAREIASAUROMORPHA Emeroleter 12 13 Macroleter 14 15 Bradysaurus seeleyi 16 For Review Only 17 Bradysaurus baini 18 PAREIASAURIA 19 Embrithosaurus 20 21 Nochelesaurus 22 23 Parasaurus 24 25 Bunostegos 26 27 Deltavjatia 28 29 Sanchuansaurus 30 31 PUMILIO- Provelosaurus 32 PAREIASAURIA 33 Nanoparia 34 35 Anthodon 36 37 Pumiliopareia 38 39 SINOPAREIA- Pareiasuchus peringueyi 40 VELOSAURIA SAURIA 41 Pareiasuchus nasicornis 42 43 Shansisaurus 44 45 Shihtienfenia 46 47 Huanghesaurus 48 THERISCHIA 49 Pareiasaurus 50 51 Scutosaurus 52 51 53 Obirkovia 54 55 ELGINIIDAE Elginia 56 52 57 Arganaceras 58 59 60