1308
Journal of Paleontology 91(6):1306–1312
side (Fig. 2). These almost certainly represent paired cerato- branchials. The right mandibular ramus is incomplete, with the anterior part of the dentary missing, but as preserved it is 23.3mm long.
When complete it was probably ~25.0–26.0mm long. The vertebral column.—The specimen is preserved essentially in complete articulation, but it is still a little difficult to be sure of the precise number of vertebrae in each specific region. In particular, there is a gap in the cervical series, while the pectoral girdle covers the anterior dorsals making it especially difficult to determine the boundary between the cervicals and dorsals. However, we consider it most likely that the new taxon had a total of between 66 and 68 vertebrae, with 11 or possibly even 12 cervicals, between 11 and 13 dorsals, two sacrals, and 41 caudals. The neurocentral sutures are closed. The neck is approximately equal in length to the trunk
(Tables 1, 2) and it seems likely that the skull is in natural articulation with the cervical series and has not disarticulated from the neck. The anterior part of the neck is obscured by matrix along with elements of the right manus (Fig. 1). The remains of eight cervical vertebrae are clearly visible and a bundle of four ribs positioned anterior to the first visible cervical vertebra (Fig. 3) indicates the occurrence of two more cervicals at the anterior end. Furthermore there would have been a much-reduced atlas giving a minimum cervical count of 11. However, in this region there may also be a sufficient gap to accommodate an additional vertebra. Many of the cervical ribs cross at least two (and possibly even three) intervertebral joints. As a consequence, at any given point
Figure 2. Pectodens zhenyuensis n. gen. n. sp. (1) Photograph and (2)line drawing with the overlying postcranial elements removed. (3) Detail of the second premaxillary tooth. Abbreviations: a = angular; ar = articular; d = dentary; ec = ectopterygoid; f = frontal; j = jugal; l = lachrymal; mx = maxilla; n = nasal; pf = postfrontal; pm = premaxilla; po = postorbital; prf = prefrontal; pt = pterygoid; q = quadrate; sa = surangular; sq = squamosal.
Paired frontals appear rather short although their anterior and posterior sutures are not clear. There is a prominent right prefrontal but determining details of the surrounding sutures is difficult. There appears to be a well-defined lacrimal (Fig. 2). The right squamosal is preserved, and its suture with the postorbital is clear (Fig. 2). The parietals appear to be completely covered by the right ilium (Fig. 2.1). The postorbital process of the jugal is thin and elongate extending posterodorsally to reach the postorbital and squamosal. There is no evidence for a posterior process on the jugal. Elements of the palate can be seen within the orbit; pterygoid teeth are small but clearly present. The full extent of these denticles is unclear, but ~15 teeth are exposed. The orbit is relatively large, which may indicate immaturity
of the individual. The skull is 25.7mm long and the orbit, as preserved, is 10.5mm long. However, the displacement of the prefrontal has caused a little distortion to the orbit so that in life it may have been a little shorter. The snout is ~11.7mm long. Two small rod-like elements with blunt ends lie in the vicinity of the anterior cervicals and the quadrate on the right
Table 1. Measurements (mm) of the individual cervical vertebrae in the holotype specimen of Pectodens zhenyuensis n. gen. n sp., IVPP V18578. Lengths are measured from the ends of the zygapophyses.
Cervical Atlas
Axis
Length -
3- 4 5 6 7 8 9
- -
11.0 11.2 11.8
10 11
~13.5* 9.3 6.7 5.9
+The ribs partly obscure the ventral edge. *A fracture passes through the bone.
Table 2. Measurements (mm) of the individual dorsal vertebrae in the holotype specimen of Pectodens zhenyuensis n. gen. n. sp., IVPP V18578. CL = centrum length; TPL = length of transverse process.
Dorsal CL
1- 2- 3 4 5 6 7
8- 9- 10 11 12
5.5 -
-
*Presumed to be completely covered by elements of the pectoral girdle **Posterior end of the centrum covered by matrix and gastralia
6.2 6.5 6.5 6.6
- **
TPL -
-
~3.8 ~4.0 -
~3.7 - - - - - -
Height -
~3.5+ ~5.7* 4.1 4.1 -
2.7 3.0 3.0
- -
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232 |
Page 233 |
Page 234 |
Page 235 |
Page 236 |
Page 237 |
Page 238 |
Page 239 |
Page 240 |
Page 241 |
Page 242 |
Page 243 |
Page 244 |
Page 245 |
Page 246 |
Page 247 |
Page 248 |
Page 249 |
Page 250 |
Page 251 |
Page 252 |
Page 253 |
Page 254 |
Page 255 |
Page 256 |
Page 257 |
Page 258 |
Page 259 |
Page 260 |
Page 261 |
Page 262 |
Page 263 |
Page 264 |
Page 265 |
Page 266 |
Page 267 |
Page 268 |
Page 269 |
Page 270 |
Page 271 |
Page 272 |
Page 273 |
Page 274 |
Page 275 |
Page 276
