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Ornithischia (Fig. 6: stem/branch 3) Definition adopted: The most inclusive clade that includes Iguanodon bernissartensis but neither Megalosaurus bucklandii nor Diplodocus carnegii (after Baron et al., 2017a). Characters in support: Horizontal or only gently arched premaxillary palate (Char. 17: 0 → 1); strongly curved and hook-shaped jugal process of the ectopterygoid (Char. 57: 0 → 1; Fig. 5E); ventrally inclined dorsal surface of the rostrum of the dentary (Char. 74: 0 → 1); retroarticular is slightly upturned at its distal end (Char. 82: 0 → 1; Fig. 7F); premaxilla with four teeth (Char. 84: 0 → 1); teeth ankylosed into the alveoli (Char. 100: 0 → 1; Fig. 7G); and medial articular facet of the proximal portion of the femur is straight in caudomedial view (Char. 213: 0 → 1; Fig. 7J).

Saurischia (Fig. 6: stem/branch 2) Definitionadopted: The most inclusive clade containing Allosaurus fragilis (Marsh, 1877) and Camarasaurus supremus Cope, 1877 but not Stegosaurus stenops Marsh, 1887 (after Langer et al., 2020). Characters in support: Subnarial foramen present (Char. 5: 0 → 1); premaxilla with a deep narial fossa at the rostroventral corner of the naris (Char. 19: 0 → 1); maxilla with significantly deeper rostrally than caudally surface ventral to the external antorbital fenestra (Char. 29: 1 → 0); caudal chonos of cranial cervical vertebrae as a shallow fossa (Char. 109: 0 → 1); epipophyses present in cervical vertebrae 6-9 (Char. 111: 0 → 1); neural arch of cervical vertebrae lower than caudal articular facet of the centrum (Char. 113: 0 → 1); articular surface of the rib of the first primordial sacral vertebra is C-shaped in lateral view (Char. 130: 0 → 1); transverse processes of sacral vertebrae roof the space between the ribs (Char. 131: 0 → 1); humerus + radius/femur + tibia length ratio less than 0.55 (Char. 141: 0 → 1); apex of deltopectoral crest between 30% and 43% down the length of the humerus (Char. 142: 0 → 1); expanded deltopectoral crest of the humerus (Char. 143: 0 → 1); humerus shorter than 0.6 of the length of the femur (Char. 145: 0 → 1); humerus sigmoid in lateral view (Char. 147: 0 → 1); average length of digits I–III of the manus more than 0.4 of the total length of humerus plus radius (Char. 153: 0 → 1); trenchant unguals on digits I–III of the manus (Char. 155: 0 → 1); deep extensor pits on distal/dorsal portion of metacarpals II-III (Char. 156: 0 → 1); width of the shaft of metacarpal IV significantly narrower than that of metacarpals I-III (Char. 167: 0 → 1); ventral margin of the acetabular wall of the ilium straight to concave (Char. 175: 0 → 1/2); distal end of the pubis slightly expanded (Char. 190: 0 → 1); kinked transition from the femoral shaft to the femoral head and expanded head (Char. 190: 1 → 2); deep groove between the lateral condyle and crista tibiofibularis on the distal end of the femur (Char. 231: 0 → 1); cnemial crest of the tibia arcs craniolaterally (Char. 234: 1 → 2); tibial articulation caudal to the ascending process of the astragalus with a markedly rimmed and elliptical fossa (Char. 249: 0 → 1); proximal articular facet for fibula of astragalus less than 0.3 of the transverse width of the bone (Char. 250: 0 → 1); cranial ascending process separated from the cranial surface of the astragalar body by a platform (Char. 256: 1 → 2); calcaneum with a concave articular surface for the fibula (Char. 261: 0 → 1); pointed caudal prong of the distal tarsal 4 (Char. 265: 0 → 1); distal tarsal 4 with a medial process (Char. 266: 0 → 1); and metatarsal IV with an expanded proximal portion (Char. 272: 0 → 1).

Thyreophora (Fig. 6: stem/branch 8) Definition adopted: The most inclusive clade that contains Ankylosaurus magniventris Brown, 1908 but not Iguanodon bernissartensis (after Sereno, 1998). Neornithischia (Fig. 6: stem/branch 9) Heterodontosauridae (Fig. 6: stem/branch 10) SYSTEMATIC PALAEONTOLOGY: PARAPREDENTATA (NOVUM) Oldest known occurrence: Lutungutali sitwensis., Published as part of Norman, David B, Baron, Matthew G, Garcia, Mauricio S & Müller, Rodrigo Temp, 2022, Taxonomic, palaeobiological and evolutionary implications of a phylogenetic hypothesis for Ornithischia (Archosauria: Dinosauria), pp. 1273-1309 in Zoological Journal of the Linnean Society 196 (4) on pages 1286-1289, DOI: 10.1093/zoolinnean/zlac062, http://zenodo.org/record/7381299, {"references":["Sereno PC. 1998. A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen 109: 41 - 83.","Dzik J. 2003. A beaked herbivorous archosaur with dinosaurian affinities from the early Late Triassic of Poland. Journal of Vertebrate Paleontology 23: 556 - 574.","Barrett PM, Butler RJ, Mundil R, Scheyer TM, Irmis RB, Sanchez-Villagra MR. 2014. A palaeoequatorial ornithischian and the new constraints on early dinosaur diversification. Proceedings of the Royal Society B 281: 6.","Butler RJ, Galton PM, Porro LB, Chiappe LM, Erickson GM, Henderson DM. 2010. Lower limits of the ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America. Proceedings of the Royal Society B 277: 375 - 381.","Martz JW, Small BJ. 2019. Non-dinosaurian dinosauromorphs from the Chinle Formation (Upper Triassic) of the Eagle Basin, northern Colorado: Dromomeron romeri (Lagerpetidae) and a new taxon, Kwanasaurus williamparkeri (Silesauridae). PeerJ 7: e 7551.","Nesbitt SJ, Langer MC, Ezcurra MD. 2019. The anatomy of Asilisaurus kongwe, a dinosauriform from the Lifua Member of the Manda Beds (~ Middle Triassic) of Africa. Anatomical Record 303: 813 - 873.","Cooper MR. 1985. A revision of the ornithischian dinosaur Kangnasaurus coetzeei Haughton, with a classification of the Ornithischia. Annals of the South African Museum 95: 281 - 317.","Crompton AW, Charig AJ. 1962. A new ornithischian from the Upper Triassic of South Africa. Nature 196: 1074 - 1077.","Sereno PC. 2005. Stem Archosauria v. 1.0. In: Sereno PC, McAllister S, Brusatte SL. TaxonSearch: a relational database for suprageneric taxa and phylogenetic definitions. PhyloInformatics 8: 1 - 25.","Owen R. 1842. Report on British fossil reptiles. Part 2. Report of the British Association for the Advancement of Science (Plymouth) XI: 60 - 204.","Seeley HG. 1888. On the classification of the fossil animals commonly named Dinosauria. Proceedings of the Royal Society of London 43: 165 - 171.","Ferigolo J, Langer MC. 2006. A Late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone. Historical Biology 19: 1 - 11.","Romer AS. 1956. Osteology of the reptiles. Chicago: University of Chicago Press.","Nabavizadeh A, Weishampel DB. 2016. The predentary bone and its significance in the evolution of feeding mechanisms in ornithischian dinosaurs. The Anatomical Record 299: 1358 - 1388.","Marsh OC. 1894. The typical Ornithopoda of the American Jurassic. American Journal of Science and Arts 48: 85 - 90.","Nesbitt SJ. 2011. The early evolution of archosaurs: relationships and origin of major clades. Bulletin of the American Museum of Natural History 352: 1 - 292.","Holliday CM, Nesbitt SJ. 2013. Morphology and diversity of the mandibular symphysis of archosauriforms. Geological Society of London. Special Publication 379: 555 - 571.","You H, Dodson P. 2004. Basal Ceratopsia. In: Weishampel DB, Dodson P, Osmolska H, eds. The Dinosauria, 2 nd edn. Berkeley: University of California Press, 478 - 493.","Sereno PC. 2012. Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs. ZooKeys 226: 1 - 225.","Baron MG, Norman DB, Barrett PM. 2017 a. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543: 501 - 506."]}

A layer of keratinous scutes encased the skull of Scelidosaurus. The neurocranium as well as the associated principal sensory systems of this dinosaur are described. The cranial musculature is reconstructed and a subsequent functional analysis suggests that jaw motion was orthal, allowing pulping of vegetation and some high-angle shearing between opposing teeth. Wishboning of the lower jaw was enabled by transverse displacement of the quadrates; and the long-axis mandibular torsion that occurred during the chewing cycle was permitted by flexibility at the dentary symphysis. Limb proportions and pectoral and pelvic musculature reconstructions suggest that Scelidosaurus was a facultative quadruped of ‘average’ locomotor ability; it retains some anatomical features indicative of a bipedal-cursorial ancestry. Hindlimb motion was oblique-to-parasagittal to accommodate the girth of the abdomen. Scelidosaurus used a combination of costal and abdominally driven aspiration. The hypothesis that respiration was an ‘evolutionary driver’ of opisthopuby in all dinosaurs is overly simplistic. A critical assessment of datasets used to analyse the systematics of ornithischians (and thyreophoran subclades) has led to a revised dataset that positions Scelidosaurus as a stem ankylosaur, rather than a stem thyreophoran. The value of phylogenetic definitions is reconsidered in the light of the new thyreophoran cladogram.