the proximodorsal margin of scapula (0), occupying a median position on the proximal shaft and curved toward the dorsal edge of the proximal scapular blade (1), developed into a promontory that overhangs the proximal end of the scapula and is not curved toward the dorsal border (2).
67. Sternal shape: reniform (0), hatchet shaped with a stout, short “handle” (1), pronounced elongation of the “handle” of the hatchet relative to the “blade” (2).
68. Carpals: fully ossified (0), fused to form a carpometacarpal I block (1), reduced to no more than two small ossicles (2).
69. Metacarpal I: elongate dumbbell shaped (0), short, block-like and fused against carpals (1), absent (2).
72. Ungual of manus digit I: claw-like (0), subconical (1), lost (2).
73. Unguals of manus digits II and III: claw-like (0), flattened, twisted and hoof-like (1).
74. Manus digit III: four phalanges (0), three phalanges (1).
75. Ilium, preacetabular process: long, laterally compressed (0), axially twisted so that lateral surface faces dorsolaterally (1).
76. Ilium: profile of dorsal edge. Horizontal to slightly arched, no significant notch in its profile posterodorsal to the ischiadic peduncle (0), sinuous profile created by the presence of a broad saddle-like notch (1).
77. Ilium: dorsal margin development: no transverse thickening of the dorsal edge in the region posterodorsal to the ischial peduncle (0), transversely thickened, beveled edge (1), thickened edge developed into a thick rolled edge (2), prominently everted, with a downturned, flap-shaped pendule that overhangs the ischiadic peduncle (3).
78. Ilium: postacetabular process in profile. Vertical plate with rounded edge (0), generally triangular, tapering posteriorly (1), laterally compressed and relatively narrow, rectangular bar (2), upturned plate (3).
79. Pubis: anterior ramus form: short (0), elongate (1).
80. Pubis: anterior ramus shape. Short, deep and blunt (0), rod-shaped (1), laterally compressed parallel-sided blade (2), expanded distally (3), strongly transversely compressed and deeply expanded distal portion (4).
81. Pubis: posterior ramus. Terminates bluntly adjacent to distal end of ischium (0), shorter than ischium, tapers to a point (1).
83. Ischium: shaft morphology 2. Compressed and blade-like along length of shaft (0), sub-cylindrical shaft (1), narrow, angular-sided shaft (2).
84. Ischium: shaft morphology 3. Distal end unexpanded (0), distal end expanded into “boot” (1), distal end laterally expanded, rather than expanded anteroposteriorly (2).
85. Ischium: obturator process. Absent (0), positioned near mid-shaft (1), positioned close to pubic peduncle, from which it is separated by an embayment (2).
86. Femoral head grooved posteriorly: present (0), absent (1).
87. Femur: curvature of shaft. Femoral shaft bowed along its length (0), proximal half of the shaft straight, distal half of shaft curved caudally (1), femoral shaft straight (2).
89. Femur: distal extensor groove. Absent (0), very broad trough (1), U-shaped trough (2), partially enclosed by expansion of adjacent anterior condyles (3), edges of trough meet to form a fully-enclosed tunnel (4).
90. Femur: distal condyles. Moderately expanded anteroposteriorly (0), strongly expanded and partly occluding flexor channel (1). Most probably a size-related mechanical feature.
91. Metatarsal I: well developed and articulates with proximal phalanx (0), slender and splint-like (1), absent (2). Difficult to assess in many instances. As in the case of a palpebral bone on the orbital margin, is absence actual evidence of absence, or a biostratinomic artifact?
92. Pedal phalanges: shape. Dorsoventrally flattened but elongate and pointed (0), elongate, bluntly truncated tip with prominent claw grooves retained (1), anterior margin broadly rounded in dorsal view, lateral claw grooves absent (2).
3
Osteology of the Basal Hadrosauroid Equijubus normani (Dinosauria, Ornithopoda) from the Early Cretaceous of China
Andrew T. McDonald, Susannah C. R. Maidment, Paul M. Barrett, Hai-lu You, and Peter Dodson
ABSTRACT
The basal hadrosauroid Equijubus normani is rediagnosed and fully described based upon the holotype and only known specimen, IVPP V 12534, from the Lower Cretaceous Xinminpu Group of Gansu Province, China. Equijubus can be diagnosed by a suite of cranial (finger-like process on the maxillary process of the jugal, rostrally elongate lacrimal) and vertebral (epipophyses present on third cervical vertebra, hyposphene present on at least dorsal vertebrae 6–8 and 11–15) autapomorphies, and a unique combination of characters. Comprehensive description of the skull and partial postcranium of IVPP V 12534 allows Equijubus to be compared to other iguanodontians from China and elsewhere. A better understanding of the anatomy of Equijubus will be useful for assessing the diversity of Asian iguanodonts, and allow it to be more confidently placed in a phylogenetic context.
INTRODUCTION
During much of the nineteenth and twentieth centuries, Europe boasted the richest fossil record of basal (i.e., non-hadrosaurid) iguanodontian dinosaurs in the world (Buffetaut and Le Loeuff, 1991; Weishampel et al., 2003; Norman, 2010, 2011a, this volume; Barrett et al., 2011). However, recent discoveries have revealed an abundance of new taxa from Asia, particularly China; recently named taxa include Nanyangosaurus zhugeii (Xu et al., 2000), Jinzhousaurus yangi (Wang and Xu, 2001; Barrett et al., 2009; Wang et al., 2010), Shuangmiaosaurus gilmorei (You, Ji, et al., 2003), Equijubus normani (You, Luo, et al., 2003), Lanzhousaurus magnidens (You et al., 2005), Penelopognathus weishampeli (Godefroit et al., 2005), Jintasaurus meniscus (You and Li, 2009), Bolong yixianensis (Wu et al., 2010), and Xuwulong yueluni (You et al., 2011). Although it is represented by one of the most complete skeletons known for these taxa, Equijubus has received only a brief description (You, Luo, et al., 2003).
We present herein a complete osteological description of the holotype and only known specimen of Equijubus, including elements that were not described or figured in the original description, and we provide a revised diagnosis for the taxon. The additional information presented on Equijubus in this description will facilitate comparison with other basal iguanodonts and allow its phylogenetic affinities to be more adequately tested. As is evident from the long list of taxa above, new Chinese iguanodonts are being discovered at a rapid pace, and it is essential when diagnosing new taxa that full comparisons with other iguanodonts are possible. Detailed descriptions of existing Chinese taxa, such as Equijubus and Jinzhousaurus (Barrett et al., 2009; Wang et al., 2010), will aid such comparative study.
Institutional Abbreviations AMNH, American Museum of Natural History, New York; CEUM, College of Eastern Utah Prehistoric Museum, Price, Utah;
