taxonID	type	description	language	source
B66BDD2A082BFF9EE36774C5FEB6E16B.taxon	description	The surfaces of the skull and mandible (Fig. 4) are coated by widespread exostoses and a small number of discrete osteoderms. This suggests that the scelidosaur skull was encased by an array of keratinous epidermal scutes or plates. For comparison, an osteological preparation of the skull of a similarly sized subadult green turtle [Chelonia mydas (Linnaeus, 1758) – Norman, personal collection – Fig. 5 A, B] – a taxon belonging to the clade Testudinata with putative (sister-taxon) archosaur affinities (Crawford et al., 2012) – reveals similarly heavily textured skull roofing bones that, in life, are known to anchor a tessellate covering of keratinous scutes (Fig. 5 C, D). Unfortunately, this particular specimen does not show the pattern of smooth, shallow grooves that mark the edges of some of the principal cranial scutes (Penkalski, pers. comm. March 2020). The premaxillary beak In Scelidosaurus a rhamphotheca was, without much doubt, an externally smooth casque-like structure referred to as a tomium in Chelonia (Fig. 5 C, tom) that enveloped the premaxillae (Fig. 6, rsc). The external surface of the premaxilla (not including the narial fossa) is slightly rugose and pitted with small foramina that in combination would have supported, anchored and indicate the presence of a vascular supply that provided nutrients for the growth of an overlying rhamphotheca; closely comparable osteological features are seen underlying the tomium of the turtle. The scelidosaur rhamphotheca formed a short cuttingedge along the edentulous margin of the premaxilla (Figs 4, 6). The slightly rugose and vascularized lateral wall to the dentulous portion of the premaxilla is likely to have been similarly encased by a posterior extension of the rhamphotheca, in conformity with the structure seen in Chelonia. It is probable that the premaxillary dentition was ensheathed (and supported) by this portion of the keratinous beak; the crowns of the teeth are envisioned projecting from behind the rhamphothecal parapet (Fig. 6 A), even though there is no modern analogue for such a composite arrangement. The dorsal portion of the rhamphotheca coated the external surface of the premaxillae and would have extended as far dorsally as the base of the dorsomedian premaxillary process, but would have been cut back so that it skirted the ventrolateral portion of the external naris. Its posterodorsal edge would have merged with the rhamphothecal margin near the posterior end of the premaxilla on either side of the snout (Fig. 6 A). The snout Anteriorly, the dorsal surface of the nasals (Fig. 4 B) is characterized by a radiating pattern of strands of bony tissue that may have anchored a midline scute (Fig. 6 A, B, nmsc); this underlying bony pattern corresponds to that which supports similar midline scutes on the chelonian skull (Fig. 5 B, D). Farther posteriorly, the surface of these bones develops a thicker knobbly texture that is overprinted by a series of repeated curved ridges. The ridges are oriented (more or less) transversely across the roof of the snout and extend down the sides of the snout where it is walled by the maxilla and prefrontal. The repetition of the curved ridges is suggestive of attachment sites for successive (possibly overlapping) scutes that encased the snout above the buccal emargination and extended posteriorly as far as the nasofrontal suture (Fig. 6, nsc). The lateral wall of the snout formed by the maxilla and premaxilla is reconstructed here covered by a large maxillary scute (Fig. 6, msc), but there are indications (Fig. 4 A) of faint attachment ridges, so it is possible that a series of overlapping scutes were found here as well. Posterior to the reconstructed lateral maxillary scute there is a smooth patch of bone (Fig. 6,?) behind which the lacrimal bears irregular exostotic growth that would have supported an overlying scute (Fig. 6, lsc). There is no equivalent patterning of successive curved exostotic ridges on the chelonian skulls that I have examined, so the scute pattern in the scelidosaur skull probably differs from the mosaic-like tessellate pattern of scutes seen in these living, albeit distantly related, diapsid taxa (Fig. 5). The skull roof and occiput The frontals are dominated by a dense pattern of strand-like superficial bone that radiates from a midline groove (Fig. 4 B). As with the anterior portion of the nasal, this morphology is suggestive of the presence of a large, shield-like scute (Fig. 6 B, fsc) that extended across to the adjacent surfaces of the prefrontal, middle supraorbital and postorbital. Lateral to the frontal plate, the palpebral (= anterior supraorbital) and posterior supraorbital osteoderms form a shallowly arched bar of bone (= brow ridge) that flanks the dorsal orbital margin of the skull roof. The rugose external surfaces of these bones are structurally distinct from the frontal plate, and are likely to have anchored their own substantial keratinous sheaths (Fig. 6, sosc) that served to shield the orbit and its associated soft tissues. It is possible that these keratinous scutes were subdivided into smaller units than illustrated here, and may have been superficially ornate for behaviourally related reasons; enlarged, sculpted and colourful circumorbital scutes are seen in many living squamates. A rugose, double-ridged sagittal crest dominates the posterior part of the skull roof. The ridges are flanked by large ovoid supratemporal fenestrae and behind these latter is a divergent pair of prominent, curved, horn-like occipital osteoderms. The temporal arches and occipital margin show some evidence of irregular exostotic growth that may well reflect the attachment of overlying scutes (Fig. 6, stsc). It is, of course, possible that this posterior part of the skull table was less extensively scute-covered. The fenestrae themselves would have been spanned by skin that (although scaly) retained a degree of flexibility to allow movement of the underlying temporal musculature. The same consideration should also apply to the adjacent infratemporal fenestrae (itsc). However, there are areas of the skull of Chelonia mydas where exostotic bone is absent and the bone surface is, instead, smooth-surfaced (Fig. 5 A, au); this area (the margins of which are dotted in Fig. 5 C) is covered in life by several scutes (Fig. 5 C, ausc). Therefore, it is possible that in Scelidosaurus tessellated scutes enveloped the posterior skull roof, as well as its lateral flanks. The restoration (Fig. 6 A, B) includes an imaginary array of rather large scutes in these areas. The occipital osteoderm ‘ horns’ have comparatively smooth, finely grooved surfaces pock-marked by many tiny foramina; these features are interpreted as a combination of points for the connective tissue that tethered an overlying keratinous horn (Fig. 6, hsc), and the vascular supply for its continued growth. Similar textures are visible on the horn-cores of living bovid mammals (e. g. Ovis aries – Norman, pers. colln – Fig. 7 A, hc). As can be seen in this example, the shape of the horn core may not necessarily have a direct bearing on that of the overlying keratinous sheath (Fig. 7 B, kh); the same may be true in the case of the scelidosaur, but in the absence of new discoveries of scelidosaur material in the Lias exhibiting exceptional preservation (e. g. Arbour & Evans, 2017; Brown, 2017), there is no way of judging on the matter, so a conservative restoration has been illustrated.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0835FF8AE0A372B0FD52E72D.taxon	description	A diet of terrestrial plants requires a variety of modifications to be made to the digestive system (King, 1996; Sues, 2000). Land plants have a skeletal scaffold formed by a combination of structural polymers: lignin, hemicellulose and cellulose, none of which can be hydrolysed by vertebrate gut enzymes. To release the soluble contents of plant cells, their lignin / cellulose fabric needs to be broken down. This process is started in the mouth using teeth and jaw muscles. There is structural evidence in Scelidosaurus for a small, sharp keratinous beak that was narrow so that the animal was capable of cropping plant material (perhaps more succulent items) selectively. Once in the oral cavity, a modest amount of pulping and shearing of plant tissue occurred prior to swallowing, judged by the morphology of the dentition. The structure of the gut into which the browse was passed is unknown in Scelidosaurus but the wide span of the ribcage (Norman, 2020 b) indicates that the torso was broad. In its proportions and general body shape, Scelidosaurus more closely resembles those seen in ankylosaurs (Fig. 22 A), than the vertically extended (narrow and deep) torso morphology exhibited by stegosaurs (Fig. 22 B). It is reasonable to assume that a modest amount of chewing of ingested plant material occurred in the mouth. However, the residence time in the gut to allow for the enzymatic breakdown of lignin and digestion of cellulose would be expected to be long, prior to absorption and assimilation of the plant breakdown products. There are additional factors to be considered, such as the presence of antipredation chemical defences produced by the plants, such as alkaloids, terpenoids, condensed and hydrolysable tannins (Swain, 1976), as well as the relative succulence and physical texture of the browse. A crop can be inferred (because it is present in living archosaurs) as a specialized sac-like compartment at the base of the oesophagus, adjacent to the stomach. The crop can store and chemically prepare the browse for subsequent digestion by softening and enzymatically detoxifying plant tissue. Herbivorous reptiles and birds have a far greater tolerance of alkaloids than, for example, crop-less herbivorous mammals (King, 1996). This may in part be attributed to the ability of the former groups to chemically neutralize these poisons in the crop before they enter the absorptive part of the digestive system. The stomach of living birds and crocodiles is also modified by the presence of a muscular gizzard whose walls are abrasive and used to physically pulverize the plant tissues (or large bones in the case of crocodiles) in preparation for digestion. Birds and crocodiles are known to swallow grit or stones (gastroliths) that become lodged in the walls of the gizzard and assist in the physical breakdown of food in the stomach (gastroliths are also known to serve as ballast in crocodiles – Taylor, 1987). Beyond the stomach and gizzard, the intestine has an absorptive section (small intestine) that can remove soluble plant cell contents released by the crushing of their tissues. In herbivorous birds, this region of the gut contains a series of blind-ended pouches (caecae). The caecae are diverticulae in the gut (sometimes spirally coiled) into which the partly digested and crushed plant material passes for further digestion mediated by symbiotic microbes (prokaryotes and protistans). Unlike their vertebrate hosts, these microbes are capable of producing enzymes that hydrolyse plant cell walls by converting them to breakdown products, such as sugars and volatile fatty acids (McBee, 1977). Enzymatic breakdown of the plant cell walls releases sugars, proteins, minerals and vitamins that can be absorbed through the lining of the caecum and small intestine. The process of providing nutrition to the population of symbiotic microbes boosts their population, which in turn allows the host to absorb amino acids and other breakdown products derived from cell death among symbionts. In living herbivorous lizards (and mammals), the more distal region of the gut accommodates a voluminous caecum that arises at the junction of the small and large intestines (Romer & Parsons, 1980). The size of the abdominal cavity simply reflects the storage capacity of the gut and its ability to cater for the lengthier phases of digestion and absorption inherent in a vegetarian diet. Only in exceptional circumstances are traces of the soft tissues of the gut (cololites) preserved (Dal Sasso & Signore, 1998; Ji et al., 1998), but in the case of Scelidosaurus there is, to date, no known preservation of gut tissues or gastroliths in association with the abdominal cavity that might illuminate gut structure and function. RESPIRATORY SYSTEM The respiratory systems of dinosaurs are not preserved but they are so central to the development of an understanding of the physiology and metabolic status of these animals that they have become a persistent subject of investigation. Carrier & Farmer (2000 a, b), Perry (2001) and Perry & Sander (2004) did much to promote debate on this topic by focusing on the respiratory potential in dinosaurs, given what was then known about the skeletal mechanics and respiratory physiology of extant squamates, crocodiles and birds. The close relationship between theropod dinosaurs and birds (Huxley, 1868; Ostrom, 1976; Xu et al., 2014) focused much of the subsequent discussion about dinosaur lung structure on the osteological correlates identifiable in theropods: pneumatized bones, uncinate ribs and gastralia (Claessens, 2004; O’Connor & Claessens, 2005; Codd et al., 2008; Benson et al., 2012) and, to a lesser extent, sauropods (Britt, 1997; Perry & Reuter, 1999). Benson et al. (2012: 188), in an article that focused solely upon skeletal pneumaticity and its implications for dinosaurian (including bird) physiology, noted that Ornithischia is a clade of diverse and abundant dinosaurs that is deeply nested within ornithodiran archosaurs and yet lacks a pneumatic postcranium, implying that this factor needed to be reconciled in any model of dinosaurian biology. Aspiratory respiration became established in amniotes ancestral to Archosauria, resulting in the potential to increase the overall efficiency of gas exchange among these animals (Perry & Sander, 2004). Most models of amniote respiration were understood to be driven by muscle-induced repositioning of the ribs to change the volume of the thoracic cavity (costal aspiration). However, it has become clear that respiration can be augmented by cuirassal aspiration (indicated by the presence of an abdominal skeleton of gastralia – belly ribs) and pelvic aspiration (dependent upon an ability to flex either the entire pelvis against the dorsal vertebral column or specialized parts of a fixed pelvis – Carrier & Farmer, 2000 a, b). In living birds, highly compliant air-sacs evolved in association with a unidirectional (‘ flow-through’) lung structure. A strictly comparable respiratory system was hypothesized for theropods ancestral to birds (O’Connor & Claessens, 2005; Benson et al., 2012). Abdominal wall compliance probably increased in birds with the loss of gastralia. However, cross-current (unidirectional) gas-exchange systems were then identified by Farmer & Sanders (2010) in the lungs of alligators. The strong similarity in air-flow patterns in the lungs of birds and crocodilians suggests that these features are plesiomorphic for Archosauria (Schachner et al., 2013 a). Flow-through lungs are also now recognized more widely among diapsid amniotes, including squamates (Schachner et al., 2013 b; Cieri & Farmer, 2016), so the inference of the existence of this type of lung in dinosaurs cannot seriously be doubted.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0831FFB7E0AE7779FBEBE20D.taxon	description	Costal aspiration: Brocklehurst et al. (2017) examined rib mobility in juvenile alligators. One particular consideration was the arrangement of the para- and diapophyseal articular facets along the dorsal series and the degree to which the positioning of the facets affected rib motion. Archosaurs (and alligators are no exception; Brocklehurst et al., 2017: fig. 1; see also: Norman, 1980: figs 34, 37) display migration of these facets along the dorsal vertebral series: the parapophysis rises from the lateral surface of the centrum to the transverse process and then migrates toward the distal end of the latter before finally merging with the diapophysis. In Scelidosaurus, the parapophyses of the first three dorsals rise sequentially to occupy a position on the anteroventral edge at the base of the transverse process. However, once this position is attained, no further migration takes place until the last two dorsals in the series (Norman, 2020 b: figs 20, 21). The parapophyseal facets are all dimple-shaped and smoothly concave, indicating a normal synovial joint. The diapophyseal facets are more complex having a ventral half that is synovial and a dorsal half that is pockmarked by ligament pits (Norman, 2020 b: fig. 16, pits), suggesting that the upper half of the suture between the diapophysis and tuberculum formed a firmer, fibrous joint. The ribs are notable for their span when placed in articulation (Norman, 2020 b: fig. 34): the back of the animal was broad, rather than narrow and deep. The distal ends of the thoracic ribs are bluntly truncated, indicating that their ends articulated with sternal rib cartilages (none of the latter are preserved). The presence of facets on the trailing edges of some of the longer anterior dorsal ribs, as well as what appears to be a partly mineralized plate (Norman, 2020 b: fig. 35 A), shows that uncinate plates were present – but may have been localized to the middle of the shafts of the longer thoracic ribs – and similar indications of uncinate plates have been reported in other ankylosaurs (e. g. Brown, 1908; see also: Gilmore, 1930) and the basal stegosaur Huayangosaurus (Zhou, 1984: fig. 19). The more specialized slender uncinate processes reported in some avialians have been linked to the mechanics of the respiratory system (Codd et al., 2008). Recent work (Codd et al., 2019) has also shown that in alligators the iliocostalis musculature is attached to the uncinate plates on the ribs and was capable of facilitating rib movement, augmenting thoracic compression (exhalation) under terrestrial conditions. Slender, uncinate processes are present on all the dorsal ribs of the extant lepidosaurian Sphenodon, but these have muscular connections to the gastralia and may be associated with cuirassal aspiration (Codd et al., 2019). In Scelidosaurus, the uncinate plates are mineralized sheets of tissue (probably cartilage) that are in their structure more similar to the flap or flangelike uncinate plates seen in crocodiles. These are here interpreted primarily as rib stabilizers or ‘ spacers’, but there is the possibility that they also anchored iliocostalis musculature that facilitated exhalation, as described in alligators. Ribs may also play a role in supporting the osteoderms that form conspicuous rows running the length of the torso. The most prominent osteoderms are found along the flanks of the animal and lie adjacent to the distal ends of the rib shafts. There is superficial similarity between the osteoderms covering the back of Scelidosaurus and those seen in crocodiles, but crocodilian osteoderms are more closely packed and articulate, creating a flexible dermal carapace, whereas those of this dinosaur do not articulate (apart from in the cervical region), being more widely spaced. The area between individual torso osteoderms comprises a semi-flexible dermis formed by a mosaic of much smaller osteoderms (Norman, 2020 c: fig. 36). Individual large osteoderms are lightly constructed, with a thin cortex and a cancellous medulla (Norman, 2020 c: fig. 43), so the weight of the dermal armour was unlikely to have been excessive. The extent to which osteoderms were anchored by ligaments to the ribcage and formed part of a tension system similar to that seen in extant crocodilians is unclear, but is considered to be unlikely, given their widely spaced and nonarticular arrangement in the thoracic region. The ossified tendon bundles that flanked the neural spines of the dorsal vertebrae would have tensioned the backbone in an analogous manner to the osteodermbased tension system of crocodilians. However, the larger osteoderms were likely to have been capped by keratinous sheaths (Brown, 2017) and formed rows of defensive spikes. Firm anchorage in the dermis and to the underlying skeleton (ribs) might be expected – and this anchoring is perhaps reflected in the preservation of semi-natural arrays of these osteoderms in some articulated skeletons (e. g. BRSMG LEGL 0004 – Norman, 2020 c: fig. 8). Overall, the ribcage of Scelidosaurus has a broad span and there was a conspicuous uniformity in the articular relationships (and range of possible movements) of the thoracic ribcage. Rib motion is likely to have been of the bucket-handle type (Brocklehurst et al., 2017), which would have permitted modest volumetric change in the thoracic cavity. This may have been augmented by the iliocostalis musculature that, in alligators, inserted on the uncinate plates (Codd et al., 2019). The longer thoracic ribs were stabilized proximally by fibrous connections running across the diapophyseal – tubercular joints, and their shafts were ‘ spaced’ distally by the presence of cartilaginous uncinate plates (that became mineralized in more mature individuals), so that the thoracic ribs moved as a parallelogram-like unit. The ribs supported and helped to anchor the larger osteoderms. However, there is no convincing evidence that the ribs and osteoderms formed a tensioning system that stiffened the backbone, as in crocodiles. Modest uniform flexure of the thoracic ribs provided a mechanism for costal aspiration. Cuirassal aspiration: In the absence of gastralia, there is no osteological evidence for cuirassal aspiration and this aspiratory mode is considered improbable by Carrier & Farmer (2000 a). Diaphragmatic aspiration: Aspiratory mechanisms akin to those seen in extant crocodilians cannot be entirely discounted because diaphragmatic muscles might have been anchored to the prepubic blades, although their lateral positioning counts against this possibility, provided that the crocodilian model of hepatic pistoning is an applicable comparator. Pelvic aspiration: The observations of Carrier & Farmer (2000 a) prompt brief consideration in relation to the respiratory capacity / potential in Scelidosaurus. Pelvic flexure (between the dorsal vertebrae and sacrum) can be excluded, given the presence of bundles of ossified tendons that run along the entire dorsal series and are anchored to the sacrum. These would inhibit flexure between the dorsal series and sacrum. The pubis and ischium are not fused to the ilium but articulate with the latter via thick connective tissue pads. The pubic shaft and ischium are equal in length, whereas the prepubic process forms a laterally directed blade. In basal ornithischians (Lesothosaurus – Baron et al., 2017 a; Heterodontosaurus – Santa Luca, 1980; Galton, 2014), the prepubic process forms a rectangular plate that projects anteriorly beneath the preacetabular process of the ilium to a greater extent than indicated in the reconstruction of Carrier & Farmer (2000 a: fig. 11 A). In Scelidosaurus, the prepubic process is short in juvenile individuals (NHMUK R 6704: Norman, 2020 b: fig. 73) but becomes a more substantial rectangular plate in larger (subadult) individuals (Norman, 2020 b: fig. 74). The pubic shaft is a long rod, co-terminous with the distal end of the ischium and lies against the shaft of the ischium. The Carrier – Farmer model of rotation of the pubic shaft permits the prepubic blade, if adducted, to compress the broadly expanded posterior abdominal wall. If diverticula or air sacs were present (unknowable), respiration would have been augmented. A model involving a combination of costal (possibly diaphragmatic?) and pelvic aspiration (achieved by pubic mobility) is at least plausible for Scelidosaurus. OPISTHOPUBIC PELVIC STRUCTURE: A REFLECTOR OF HERBIVORY OR RESPIRATORY BIOLOGY? Macaluso & Tschopp (2018) argued that it was necessary to demonstrate that respiration was more likely to be an ‘ evolutionary driver’ of opisthopuby in dinosaurs than was herbivory. The basis for this proposition was a false premise: that opisthopuby in all dinosaurs had previously been causally linked to the adoption of an herbivorous diet. Furthermore, they claimed that this idea had been proposed by Weishampel & Norman (1989). However, Weishampel & Norman never made such a claim in that article. Rather opisthopuby, which characterizes Ornithischia, was proposed as a biomechanical adaptation that permitted small ornithischian herbivores to retain a bipedal posture and limb proportions indicative of cursoriality in the face of predation by coeval bipedal and cursorial theropods (Norman & Weishampel, 1991). This latter proposition was never expanded by these authors to encompass all dinosaurian subclades. The evolution of an analogous form of opisthopuby among some avian-theropods, although interesting per se from an evolutionary perspective – particularly in light of the work of Baron et al., (2017 b, c) – has always been considered (certainly by Norman and Weishampel) to be a functionally and physiologically unrelated matter. An awareness of cranial adaptations that can be interpreted as indicators of a herbivorous or omnivorous diet among theropods (traditionally considered exclusively carnivorous) was highlighted in a general review by Barrett & Rayfield (2006). Their general thesis was further developed by Zanno et al., (2009) in which a wider range of cranial, as well as postcranial, morphologies, and their distribution among taxa, were mapped phylogenetically across a range of coelurosaurian theropods (Zanno et al., 2009). They concluded that coelurosaurian theropods were not primitively ‘ hypercarnivorous’ but were dietarily flexible, ranging from herbivory through omnivory to carnivory, and that strict carnivory was a secondary specialization found in one group of paravian theropods (dromaeosaurids). The recognition of dietary flexibility among coelurosaurians was posited as an evolutionary benefit because it allowed them to be dietary opportunists. Returning to the issue of respiration vs herbivory as a driver of opisthopuby, Gatesy & Dial (1996 a, b) demonstrated that the evolution of opisthopuby is coupled with a reconfiguration of body proportions and limb function among Avialae. This alteration presaged the ‘ modularized’ bodies of extant birds. In short, the tail undergoes progressive reduction in its skeletal and muscle mass; as a consequence, the cantilevering effect of the tail is reduced and it simultaneously reduces its capacity to anchor the principal hindlimb retractor muscles (m. caudifemoralis longus). An anatomical marker reflecting the reduction of the femoral retractor musculature is the size and prominence of the femoral 4 th trochanter, which progressively reduces before disappearing completely in ‘ paravian’ theropods (see Fig. 28). To maintain a bipedal pose, a number of subclades of shorter- or slender-tailed avian-theropods evolved degrees of pubic retroversion, ranging from intermediate (mesopuby) to full opisthopuby – followed by eventual separation of the pubes and ischia in the midline so that the abdomen can extend posteriorly beneath and behind the sacroiliac vault (see Figs 27, 28). These changes reflect a rebalancing of the body to compensate for the loss of the cantilevering effect of the tail. There is also a consequential repurposing of the hindlimb. The femur becomes an exclusively anteriorly directed suspension member of the hindlimb, and the knee-joint adopts the role of a ‘ neoacetabulum’. The anteriorly displaced knee-joint becomes the centre of balance and the locomotor stride of the hindlimb is achieved by swinging the elongated tibiotarsus and tarsometatarsus, pendulum-like, from the knee (as is the case in extant birds). In this general context, gross expansion of the gut cavity and retroversion of the pubis (linked to a shortening of the tail), and the maintenance of a bipedal stance, can be correlated with herbivory in the highly modified opisthopubic condition described in therizinosaurs, such as Nothronychus (Zanno et al., 2009), but these are truly exceptional theropodans (see Fig. 27 D). OBSERVATIONS Macaluso & Tschopp (2018) undertook a study that was purposely restricted in scope: they limited the biological ‘ drivers’ considered to just two. In terms of logic, the study is internally consistent, in that they consider whether dinosaurs exhibit carnivory, omnivory or herbivory, assign these traits to the taxa under consideration and then plot their assignments on a general phylogeny (Macaluso & Tschopp, 2018: fig. 2). They indicate, on that phylogeny, the presence or absence of gastralia and whether pelvic anatomy was ‘ propubic’, ‘ mesopubic’ or ‘ opisthopubic’ – employing the terminology adopted by Rasskin-Gutman & Buscalioni (2001). Dinosaur taxa (representative of selected dinosaurian subclades) are then scored according to the authors’ interpretation of pelvic morphology, diet and respiratory capacity. An analytical protocol was applied to their scores, which promotes the view that opisthopuby is more strongly correlated with respiratory mechanics than with herbivory in these dinosaurs. Their approach conflates an objective analytical protocol with a set of subjective decisions concerning diet and respiratory capacity, and uses simplified twodimensional images of hip structure. They admit in the discussion section ‘ that a change in the ventilatory system was [not] the only evolutionary force acting on the structure of the archosaurian pelvis. For instance, egg morphology, locomotion, nesting behaviour and reproductive organs could all have been equally influential’ (Macaluso & Tschopp, 2018: 714). There was no mention of herbivory, but these other factors were not explored because they were considered by the authors to be ‘ more difficult to recognize in the skeleton’ (p. 714). On the basis of the published literature and available descriptions, it can be stated objectively that ornithischians and sauropods are the only dinosaur groups that show no evidence of gastralia. Representatives of all the theropod clades considered by Macaluso & Tschopp are known to possess gastralia [contra Macaluso & Tschopp, 2018: fig. 2 – note that node 4 in this figure implies that all ‘ Pennaraptoran’ taxa (oviraptorosaurs, dromaeosaurs + Sinovenator) possess gastralia and yet, paradoxically, were designated as non-cuirassal breathers]. Taken in total, the approach adopted in their article establishes a false premise and subsequently fails to account for the range and variety of anatomy, inferred biology and functional organization of these animals – all of which have a material bearing on our understanding. It has always been understood (certainly by Norman & Weishampel) that the unique evolution of the opisthopubic pelvis in ornithischians, and also seen to have arisen iteratively among some avian-theropod subclades, were independent, anatomically distinct and functionally unrelated events. To provide an overview of the biological and functional issues associated with respiratory capacity and its linkage to the evolution of pelvic structure in dinosaurs (and their extant descendants birds), a set of summary comments is offered. SUMMARY Irrespective of basal dinosaur systematics (Baron et al., 2017 b, c; Langer et al., 2017), it can be agreed (following the work of Carrier & Farmer, 2000 b) that stem-lineage taxa (dinosauromorph archosaurs) had mobile bicipital dorsal ribs and gastralia. This indicates that they were capable of using, to varying degrees, a combination of costal and cuirassal modes of aspiration. Gastralia, and by implication cuirassalstyle aspiration, are retained (symplesiomorphically) in Late Triassic dinosaurian taxa belonging to Sauropodomorpha and Theropoda (Fig. 24), but this anatomical character and the inferred aspiratory mechanism is absent (synapomorphically) in the Early Jurassic clade that has a sister-taxon relationship with Theropoda: the Ornithischia (Fig. 24) – although it does not matter from which basal dinosaurian clade the Ornithischia are derived in this regard. It is established that the iterative evolution of degrees of opisthopuby among subclades of Theropoda can be linked functionally to the reorganization of the bodies of these animals (Gatesy & Dial, 1996 a, b). It is only among Aves (flight-adapted birds) that gastralia are lost and the structural adaptations associated with the avian flow-through respiratory system can plausibly be inferred (see Fig. 27).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A080EFFB4E3047052FD54E2CB.taxon	description	The subsequent evolutionary history of the ornithischian clade demonstrates that opisthopuby was maintained, albeit with elaboration of the pelvic bones in particular subclades, and several subclades independently acquired a secondarily quadrupedal style of locomotion (Barrett & Maidment, 2017; Fig. 25 B, C).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A080DFFB3E0AE710AFB51E22F.taxon	description	Jurassic and Cretaceous sauropodomorphs (sauropods) are extremely large, pillar-limbed quadrupeds with long tails and necks (Fig. 26 B). They were microcephalous herbivores that raked and / or cropped food into the mouth before swallowing after minimal oral treatment (Barrett & Upchurch, 1994). The pelvis was mesopubic and the pubes formed a bony wall at the rear of an abdominal cavity that lay in front of the acetabulum. Quadrupedality, an arched, dorsal vertebral column and pillar-like limbs created bridge-like support for a massive gut. Food passed into a stomach that included a substantial gastrolithfilled gizzard and, judged by the space available in the torso, a voluminous (probably multichambered) gut. No gastralia are preserved in sauropods (Claessens, 2004; Fig. 24) and cuirassal aspiration is considered unlikely because it would have involved the raising and lowering of an exceptionally massive gut (Carrier & Farmer, 2000 a). The aspiratory mechanics of sauropods are not well understood, although it has been inferred (because of the presence of postcranial pneumatism) that sauropods had an avian-style flow-through respiratory system (e. g. Sander et al., 2011). Dorsal vertebrae have conventional synovial articulations for their ribs, suggesting that costal aspiration was possible. Theropoda Triassic and Early Jurassic theropods are generally small to medium-sized (2 – 5 m long) bipeds with large, muscular tails; they are considered (by all) to be carnivores and had, as a correlate, much smaller guts than typical herbivores of equivalent size (Fig. 27 A). The pelvis is propubic but the gut would have been positioned anterior to the centre of balance and was comparatively small, so was unlikely to impair balance or mobility: the tail was an effective cantilever. The thoracic rib articulations were mobile and the abdomen was floored by gastralia; this implies that early theropods / theropod-like dinosauromorphs were capable of using both costal and cuirassal forms of aspiration. From the mid-Jurassic onward, the size-range and variety of theropods increased substantially. Larger tetanuran theropods (Fig. 27 B): For example Allosaurus retains the classical body proportions and carnivorous adaptations (large skull, sharp recurved teeth, raptorial forelimbs) of basal dinosaurs, and also displays a well-developed set of gastralia. Other subclades (see below) diversified their body forms to a greater extent: Ornithomimosaurs: Generally lightly built with small heads and toothless beaks / bills (Fig. 27 C), resemble living omnivore-carnivore derivatives (ratites). In the case of the structurally similar and closely related alvarezsaurs, their jaws are lined by small teeth, instead of a beak / bill, and some authors have speculatively linked their dental features to those in animals with a myrmecophagous (ant-based) diet (Longrich & Currie, 2009). Both of these groups were scored as herbivores by Macaluso & Tschopp (2018), yet both groups have lightly built cursorially adapted skeletons, have long arms and grasping hands, are propubic and have long cantilever-like tails. This body configuration is more readily explained if they were comparatively smallgutted, pursuit adapted, carnivore / omnivores. Both groups retain a well-developed set of gastralia. Therizinosaurs (Fig. 27 D): Exhibit comparatively small skulls with jaws lined by small leaf-shaped teeth. However, their body proportions include a capacious abdominal cavity, broadly flared iliac blades, an opisthopubic pelvis and a much-reduced tail (Zanno et al., 2009). Their body form bears a passing resemblance to that seen in herbivorous xenarthrans (ground sloths). Therizinosaurs were scored, entirely appropriately, given their overall cranial and body form, as herbivores by Macaluso & Tschopp (2018). Gastralia have been reported in therizinosaurs. Oviraptorosaurs (Fig. 27 E): Are characterized by having medium sized head equipped with short, powerful toothless beaks. The pelvis is mesopubic, so the gut was positioned anterior to their centre of balance; they also have comparatively short tails and the femur lacks a prominent 4 th trochanter. These two latter features are strong indicators of a bird-like alteration to their limb mechanics to compensate for the reduced cantilever effect of the tail. Furthermore, the length and raptorial structure of the forelimbs of oviraptorosaurs (Norell et al., 2018) represent clear adaptations associated with prey capture (and hence carnivory). Oviraptorosaurs have short, powerful jaws (indicating a strong bite – which could be interpreted either way in relation to diet), and there is a report of gastroliths (in Caudipteryx). These animals were scored as herbivores by Macaluso & Tschopp (2018). The discovery of lizard remains in the body cavity of an Oviraptor, as well as those of juvenile troodontid skulls in association with a nest of Citipati, are both arguably suggestive of carnivory in these animals (Bever & Norell, 2009). Equally, crocodiles also have gizzards with gastroliths and can hardly be argued to be herbivores and, in the absence of teeth, gastroliths may have been important bone fragment processors in the gut of carnivorous oviraptorosaurs. As a general observation, the presence of a gastrolith-laden gizzard associated with an expansive and heavy gut (necessary, if these animals were indeed herbivores), which would have been positioned anterior to the centre of balance, is incompatible with the build, mechanics of balance and indications of locomotor style seen elsewhere in their bodies. Common sense suggests that oviraptorosaurs were carnivores. Oviraptorosaurs also possess welldeveloped gastralia. Stem-lineage avians (Fig. 27 F): Finally, among the paravian – avialian (stem-lineage birds), of which Deinonychus (Fig. 27 F) is a well-known example, the predatory adaptations seen in the skull, as well as those of the fore- and hindlimbs, are self-evident (Ostrom, 1969). The tail is long, but is thin and light, the femur lacks a 4 th trochanter and the pubis is fully retroverted. The balance and pose of this animal would have been bird-like and necessitated a ‘ neoacetabular’ knee-joint; an adequate locomotor stride would have been achieved by lengthening the tibia – fibula and metatarsus. The posture depicted in Fig. 27 F (a common style of reconstruction of this animal) is not accurate to these principles because it indicates that the femur swung through a pendulum-like arc, which it could not have done because it was ‘ suspensory’. Gastralia are well developed in dromaeosaurs. This general paravian body pose would have been reproduced in Archaeopteryx [the so-called ‘ first bird’ – which also exhibits gastralia, even though these bones are lost in true, flight-capable (ornithothoracine) birds]. A broader consideration of the morphofunctional organization and fossil evidence that can be applied to a diversity of theropods suggests that the dietary assignments that have been proposed in the recent past are, in many instances, open to doubt. Furthermore, in each of these theropod taxa, gastralia are known to be present, indicating that these animals had the potential to use cuirassal aspiration as a component of their respiratory repertoire. It is only among the more derived avialians that a large thoracic keel evolves, gastralia are lost, the ventral pelvic bones separate along the midline and the tail becomes so abbreviated that it forms a pygostyle – a suite of structural modifications that allow true birds to retain a bipedal pose and locomotor capacity in the complete absence of a cantilever tail. CONCLUSIONS The range of anatomical configurations exhibited by the entire dinosaurian clade includes obligate bipedality, facultative bipedality and quadrupedality, and obligate quadrupedality. These locomotor postures are co-dependent on the positioning of the gut (and its mass), as well as general pelvic construction, irrespective of the respiratory system. The structural adaptations associated with the feeding apparatus have a direct bearing on diet and gut structure in these animals, which in turn influences the balance and pose of the body. Inferences about the dietary preferences of these animals require a holistic approach that incorporates jaw morphology, tooth shape, skull size, body proportions, locomotor mechanics, limb functionality and, rarely, the fortuitous discovery of fossilized gut contents. Using this range of criteria, there is justification to doubt the scoring of the diets assigned to the various theropod subclades considered by Macaluso & Tschopp (2018). There is also clear anatomical evidence that contradicts the assignment of respiratory mechanisms among theropod dinosaurs proposed by Macaluso & Tschopp (2018). Drawing broad physiological and functional comparisons between such disparate body forms as ornithischians, sauropodomorphs and theropods risks conflations and / or misunderstandings. Even among closely related and persistently bipedal theropod dinosaurs that all possess gastralia (and by implication cuirassal aspiration), taxa are variously specialized. Some (e. g. ornithomimids) reduce their dentitions, leading to the evolution of a bird-like keratinous beak / bill; some (e. g. therizinosaurs) shorten and reduce the mass of the tail and, consequently, partially or completely retrovert the pubis; some (e. g. ‘ paravialians’) modify the pose of the hindlimb through the evolution of a suspension-style femur and alter the musculature that protracts and retracts the legs. However, these configurations are not consistent across all taxa and instead indicate a suite of adaptive morphologies that require explanation in light of the total body plan and a range of additional evidence that enhances the interpretation of the putative biology of each subclade (Fig. 28). The evidence available cannot be used to support the notion that there is a consistent, phylogenetically mappable, pattern implying that the aspiratory mechanism was the sole ‘ evolutionary driver’ of pelvic morphology among dinosaurs, as argued by Macaluso & Tschopp (2018).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A080AFFB0E3EE7089FBA5E0CF.taxon	description	The biomechanical observations of Alexander (1976) followed by the review by Walter Coombs (1978 c) prompted interest in the poses and relative proportions of dinosaur limbs, their musculature, locomotor capacity and trackway evidence (e. g. Gatesy, 1990; Carrano, 1998, 2000; Hutchinson, 2000 a, b, 2004; Hutchinson & Gatesy, 2000; Carrano & Hutchinson, 2002; Hutchinson & Garcia, 2002; Sellers & Manning, 2007). Trackway evidence does not exist for Scelidosaurus but its appendicular skeleton is now known (Norman, 2020 b) and provides information concerning locomotor musculature, joint anatomy, limb proportions and potential limb excursion patterns for this animal. PECTORAL GIRDLE AND FORELIMB MYOLOGY The pectoral girdle and forelimb musculature of thyreophorans have rarely been considered. Coombs (1978 b) attempted a reconstruction of the principal forelimb muscles in ankylosaurs. Norman (1986: figs 75 – 77) provided origin and insertion maps and a lines-of-action reconstruction for the musculature of the pectoral girdle and forelimb in the ornithischian ornithopod Mantellisaurus. These reconstructions were based on comparative myological information derived from extant crocodilians. Birds (although extant theropods) were considered too specialized in their pectoral anatomy and myology for meaningful comparison. Meers (2003) provided a beautifully crafted redescription of crocodilian forelimb musculature. Maidment & Barrett (2011) reviewed the identification of forelimb musculature in basal ornithischians (with occasional reference to the stem thyreophoran Scutellosaurus) and used the Extant Phylogenetic Bracket (EPB) protocol advocated by Witmer (1995). Using this approach, they created origin and insertion maps for some of the shoulder and forelimb muscles of these dinosaurs based on a critical evaluation of the evidence of muscle distributions in living crocodilians and birds because they phylogenetically ‘ bracket’ ornithischian dinosaurs. However, the efficacy of this approach is severely compromised by the profound differences between such disparate living representatives (Romer, 1923 b; Gatesy, 1990, 1995; Carrano, 2000). The EPB approach offers a logical basis for the prediction of some soft-tissue features in fossil animals, but its application in this instance requires the exercise of considerable caution. The anatomy of the pectoral girdle of Scelidosaurus resembles that described in other basal ornithischians (Fig. 29) and this permits some plausible mapping of the origins and insertions of the principal support and locomotor muscles.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A081CFFA3E09C756FFA28E450.taxon	description	The femur has an articular head that is medially offset from the shaft and not deflected anteromedially (as described to be the condition in dinosauromorphs and some basal dinosaurs – Carrano, 2000). The anterior trochanter is proximally placed and prominently positioned on the anterior margin of the greater trochanter. The implication from this configuration is that the femur could be swung parasagittally and was powered by musculature associated with the expanded iliac blade. The femoral shaft is slightly bowed (more so in juvenile individuals – see Fig. 32) and is notable for the presence of a prominent pendent 4 th trochanter. The medium- to large-sized (~ 32 cm long) crushed femur of Scelidosaurus (NHMUK OR 41322 – Fig. 34) has a prominent pendent 4 th trochanter. However, on closer inspection this structure is noticeably thicker and considerably more robust than that of NHMUK R 6704 (Fig. 32 A). The 4 th trochanter of the larger femur is thick, yet an outline of the slender ‘ juvenile’ 4 th trochanter morphology remains visible on its surface (Fig. 34, 4 tr). The original structure has, in effect, been shrouded by a thickness of metaplastic bone (Fig. 34, mpb). It is probable that this secondary feature expanded and strengthened the anchoring of the caudifemoral tendons and reinforced the 4 th trochanter. A pendent 4 th trochanter is consistently associated with ornithischians that, judged by their posture and limb proportions, were likely to have been cursorial (e. g. Maidment & Barrett, 2014 and references therein). The distal femoral condyles are laterally expanded, but show no clear evidence of an intercondylar extensor groove (but this is also a feature of the femur of the allegedly cursorial ornithischian Hypsilophodon – Galton, 1971, 1974). Thick cartilages would have been present that capped the bones at the knee-joint, and the structure of the preserved bones does not accurately reflect the extent to which this joint operated as a uni-axial hinge. The crus (shin) comprises a structurally dominant straight tibia and a shorter, but stout and bowed, fibula; this gives the impression that a limited amount of axial torsion might have been possible between the bones of the lower leg. The tarsus is conventionally mesotarsal but the evidence, judged by what is currently known of the structure of the astragalocalcaneal roller surface, is that the ankle joint was not so strongly constrained to rotate in a transverse uni-axial plane because it does not display a deeply grooved (trochlear) joint surface. The distal tarsals, as preserved, also present an asymmetrical arrangement with the central (dT 3) and lateral (dT 4) tarsals, forming well-ossified articular pads, whereas the medial tarsal (dT 2), if present, was probably an unossified fibrocartilage pad or (less likely) entirely absent from the ankle joint (Norman, 2020 b: figs 86, 87). The pattern of just two distal ankle bones (central and lateral) is found reasonably consistently among more derived ornithischians (in which this anatomy has been preserved, e. g. Norman 1980, 1986). The asymmetrical construction of this ankle joint would have left it potentially susceptible to (or able to accommodate) longaxis torsion during the limb excursion cycle. In the context of ankle-joint construction and joint mobility, it is interesting to note that the early (Hettangian) but unusually specialized ornithischian Heterodontosaurus has been reported as having three well-ossified distal tarsals (Santa Luca, 1980) or just two (Sereno, 2012). In either interpretation, the distal tarsal structure that is preserved forms an ossified articular pad that caps all three weight-bearing metatarsals (2 – 4) that support functional pedal digits. In turn, this tarsal structure articulated with a hinge-like and fused tibiotarsus. This ankle structure suggests that limb excursion was parasagittal and that ankle-joint mobility was restricted to a single transverse plane of rotation. The pes of Scelidosaurus is functionally tridactyl, being dominated by pedal digits 2 – 4 (Norman, 2020 b: fig. 90). Metatarsals 2 – 4 are sutured proximally and form a splayed structure distally. Metatarsal 1 is short, but supports two phalanges, the terminal one of which forms a small, pointed claw. Metatarsal 5 is represented by a splint bone. The three functional toes, as preserved in the lectotype (NHMUK R 1111 – the only currently known example that includes articulated feet), curve medially along their lengths and the terminal unguals are pointed, slightly arched, but, as with the phalanges, they are twisted medially along their lengths (Norman, 2020 b: fig. 95). Scelidosaurus pelvis and hindlimb: comparative comments The pelvis of Scelidosaurus (Fig. 31 A) bears a much closer structural similarity to that of early ornithischians and euornithopods than to those of more derived stegosaurian and ankylosaurian thyreophorans (Fig. 31 B, C; Carrano, 2000: figs 6, 7). The ilium has a long, arched (in mature individuals) dorsoventrally flattened preacetabular process, but it is not broadly expanded or downcurved to the extent seen in ankylosaurs and stegosaurs. The dorsal part of the iliac blade, though out-turned when articulated with the sacrum, is not laterally flared, and its postacetabular blade is rectangular and has a modest brevis shelf. In both stegosaurs and ankylosaurs (Fig. 31 B, C), the postacetabular blade is short and tilted horizontally. The ischium of Scelidosaurus is a Y-shaped thickened blade with a long stem. In stegosaurs, the ischium is more transversely compressed and tapers distally (Maidment et al., 2015), whereas those of ankylosaurs are considerably shorter, bar-shaped and decurved (Coombs, 1978 a). The pubis of Scelidosaurus has a long, slender pubic shaft and a blade-like, laterally deflected prepubic process. The pubis of ankylosaurs is diminutive (a small oblong block fused to the ilium) from which projects a short, finger-shaped pubic shaft (Coombs, 1978 a). In stegosaurs the pubis is a large, obtusely V-shaped bone with a parallel-sided pubic shaft that was ligamentously bound to the ischium, and a long rectangular prepubic blade (Gilmore, 1914). Stegosaurs and ankylosaurs have much more robust and straight (pillar-like) femora (Gilmore, 1914; Coombs, 1978 a). The femoral head is less clearly medially offset on the shaft (this is particularly so in ankylosaurid ankylosaurs, where the femoral head is terminal – Coombs, 1978 a). The anterior trochanter tends to become indistinguishably fused to the greater trochanter. The 4 th trochanter is represented by either a low mound or a large, depressed muscle scar on the lower half of the femoral shaft. Their crural (shin) bones of are straight and the tibia is massive, with greatly expanded proximal and distal ends; the fibula is a comparatively slender, straight bone that had little to do with structural support. The ankle comprises a single, proximal tarsal that is reduced to a flattened, warped plate formed by the astragalus, which is fused to the distal surface of the tibia. Distal tarsals have not, so far, been reported. The pes comprises short, dumbbell-shaped metatarsals and ‘ stubby’ toes; these form a divergent ‘ spreading’ arrangement that was most likely supported by a plantar pad of elasticated fibrous tissue. Their unguals are flattened, broad and rounded, distally forming a hoof, rather than a claw. FUNCTIONALITY OF THE HINDLIMB AND PES SUMMARIZED 1. Acetabulum. The acetabular joint surface is unusually large compared to the femoral articular head. It offers the possibility of a wide range of femoral head positions and consequential femoral excursions (Norman, 2020 b: fig. 98) but the extent to which soft tissues (notably cartilages) influenced the potential range of femoral excursions is uncertain (Hutson & Hutson, 2012). 2. Hindlimb joints. The knee has some of the osteological attributes of a simple hinge, but the extent to which this was constrained by soft tissues to a transverse uni-axial plane of rotation is unknowable. The structure of the lower leg, which retains a short but stout, bowed fibula, indicates that limited (modest) axial torsion may have occurred between the tibia and fibula. The ankle joint is weakly trochlear, as well as being osteologically asymmetrical. If there was a fibrocartilage pad covering the medial portion of the ankle, the entire ankle joint may have been susceptible to (or able to accommodate) long-axis torsion. 3. Hindlimb retractors. The lines of action of the caudifemoral muscles can be reconstructed (compare Figs 33, 35). The origin of the m. caudifemoralis brevis lies on the underside of the postacetabular process of the ilium and runs anteroventrally to the base of the 4 th trochanter and its line of action is posteromedial (Fig. 35 A, cfb). Musculus caudifemoralis longus is known to originate from the lateral surfaces of the caudal centra and the edges of the caudal ribs in all sauropsids (and even the equivalent pygostyle in birds) and inserts on the 4 th trochanter. The line of action (Fig. 35 A, cfl) of this retractor muscle runs anterolaterally from close to the caudal midline. In addition, the adductor muscle (Fig. 35, add) would both retract the femoral shaft (from its fully protracted state) and rotate the femoral shaft outward along its longaxis (balancing some of the inward rotation imposed by the far more powerful caudifemoral muscles). 4. The pendent 4 th trochanter is positioned on the posteromedial surface of the femoral mid-shaft (Fig. 35 C), increasing the axial rotation generated by the femoral retractor muscles. 5. Hindlimb protractors. The lines of action of the mm. iliotibialis, iliofemoralis and puboischiofemoralis internus can be reconstructed with varying degrees of confidence. Musculus iliotibialis is consistently found to originate along the dorsal edge of the iliac blade in sauropsids (including birds) and inserts on the cnemial crest of the tibia (Fig. 33, it). Musculus iliofemoralis originates on the dorsolateral surface of the iliac blade and inserts variously on the shaft of the femur and (with personal equivocation) on the anterior trochanter (Fig. 33, if) and lateral surface of the greater trochanter. At least one significant portion of the puboischiofemoralis complex originates from the proximomedial surface of the pubis, the surfaces of the posterior dorsal centra and the first sacral rib (in sauropsids). It has been suggested that a slip of this muscle attached to the ventral surface of the preacetabular process in ornithischians (Maidment & Barrett, 2011 – see also Fig. 33, pifi). This muscle inserts on the medial surface of the proximal femoral shaft and a major tendon of this muscle inserts adjacent to the 4 th trochanter in crocodiles (there is a wellpreserved muscle scar in this position on the femur of the lectotype – Fig. 32 B, pifi). The lines of action of the first two muscles can be reconstructed with some confidence and vary a little along the length of the iliac blade because the preacetabular process swings markedly laterally along its length. Musculus puboischiofemoralis has a line of action that not only serves to protract the femur, but imposes a torsional force that rotates the femoral shaft outward (laterally) in preparation for the next stride (Fig. 35 C, E). 6. Dimensions of the abdominal cavity. Scelidosaurus was herbivorous and, judged from its teeth and jaw action, would have pulped and partly sheared its food prior to swallowing. This style of oral processing is unlikely to have prepared plant matter for immediate absorption in the intestine, so it would need to be processed further in the gut. A gizzard, lined with gastroliths, cannot be dismissed simply because no gastroliths have been recorded with any of the skeletons of this animal that have been discovered to date. A gizzard is present in living crocodiles and birds, so may well have been present and used to comminute plant food in the anterior gut. However, further enzyme-mediated digestion would be necessary to release plant cell contents and can only have been achieved within gut caecae that housed permanent populations of microbes capable of secreting enzymes that can break down the tough polysaccharide (cellulose-based) cell walls of plants. Gut enlargement to accommodate caecae requires a capacious abdomen. The dorsal rib cage is indisputably broad (Norman, 2020 b: fig. 34; see Fig. 35 D, E), and the body shape is more similar to that seen in ankylosaurs (e. g. Gaston et al., 2001) than stegosaurs (see also Fig. 22), which suggests that Scelidosaurus had a barrel-shaped abdomen. 7. Deflection of the prepubic blades. The lateral deflection of the prepubic blades that is evident in Scelidosaurus is also suggestive of the physical accommodation of a broadly expanded abdomen. 8. Asymmetry of the pes. The medial curvature that is evident when the digits of the pes are articulated might be an artefact of preservation in this specimen. However, the ungual phalanges of digits 2 – 4 are well-preserved and show comparatively little in the way of crushing plastic distortion, and yet they all indicate clear medial curvature. In the tridactyl pes of a ‘ normal’ parasagittally gaited dinosaur, the axis of support tends to run through digit 3, which displays bilateral symmetry. The digits on either side splay: digit 2 curves medially, whereas digit 4 curves laterally, so that the foot as a whole exhibits some degree of symmetry on either side of the principal axis of support (e. g. Norman, 1980: fig. 71; 1986: fig. 63). The persistent asymmetry evident across the digits of the pes of Scelidosaurus implies that torsional forces in the long-axis of the hindlimb were acting on the foot during the supportretraction phase of the locomotor cycle (Fig. 35 E).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0819FFAEE370702DFC78E4BD.taxon	description	THE SYSTEMATIC AND PHYLOGENETIC POSITION OF SCELIDOSAURUS SCELIDOSAURUS, EARLY DINOSAUR CLASSIFICATION AND RELATIONSHIPS Richard Owen established that Scelidosaurus was a member of his Dinosauria, based on the structure of its hindlimb: The internal process [4 th trochanter of the femur] is similarly well preserved, repeating the character of the herbivorous Dinosauria which is exemplified in the Iguanodon [italics] …. The medullary or unossified cavity of the shaft of the bone has been more considerable, in relation to the compact shaft, than in the large femora previously described. From the foregoing characters it may be concluded that the present femur has belonged to a Dinosaur, allied to the Iguanodon [italics], …. (Owen, 1861: 5) Despite the fact that Owen was describing the characteristics of a theropod femur (Owen, 1861: tab. I – see Norman, 2020 a: fig. 2 A), his words were still applicable to other genuine scelidosaur remains that he included in this preliminary description (Owen, 1861: tab. III – see Fig. 2). Owen was notably reticent when it came to expressing views about the relationship of this new dinosaur to any of the other, then known, dinosaurs. His clearest remark was: Upon the whole, I find the closest agreement to be between Scelido - and Hylaeo-saurus in the characters of the vertebral column; …. (Owen, 1863: 12) And yet, despite Owen’s extended description of parts of the dermal skeleton of Scelidosaurus (Owen, 1863: 20 – 26), there is neither a single mention of the osteoderms visible on the slab of Tilgate Stone containing the remains of Hylaeosaurus, nor a more detailed consideration of the potential relationship between these taxa. Attempts to systematize and classify known taxa of Dinosauria began in the late 1860 s, stimulated by the work of Edward Drinker Cope (1866). Cope established two groupings or ‘ orders’ of dinosaur based on his interpretation of their supposed ankle and foot structures: Orthopoda (including Scelidosaurus, Hylaeosaurus, Iguanodon and Hadrosaurus) and the Goniopoda (Megalosaurus and Laelaps). A year later, Cope (1867) added a third order: Symphopoda, based upon his interpretation of the shin (crural), ankle (tarsal) and foot (pedal) structures in Compsognathus. The latter, he pointed out, suggested a resemblance between the feet of some dinosaurs and those of living birds. Subsequently, Thomas Henry Huxley (1868) demonstrated that the anatomical (‘ intermediate’) similarities shared between the then-known dinosaurs and living reptiles and birds provided evidence that strongly supported Darwin’s theory of evolution. Listing the anatomical differences between living reptiles and birds, Huxley proceeded to fill the anatomical ‘ gap’ between such distinctly different organisms by demonstrating that the fossil bird Archaeopteryx exhibits a number of reptilian features. Furthermore, he was able to demonstrate that the larger dinosaurs possessed many bird-like features in their sacra, pelves, hindlimbs and feet. The discovery of the small, lightly built dinosaur Compsognathus compounded the similarities between dinosaurs, Archaeopteryx and living birds, and allowed him to observe that ‘ Dinosauria wonderfully approached … birds in their general structure, and therefore that these extinct reptiles were more closely allied to birds than any which now live’ (Huxley, 1868: 73). This proposition was subsequently reinforced in a summary article (Huxley, 1870 a) that led him to conclude ‘ if the whole hind quarters, from the ilium to the toes, of a half-hatched chicken could be suddenly enlarged, ossified and fossilized as they are, they would furnish us with the last step of the transition between Birds and Reptiles; for there would be nothing in their characters to prevent us from referring them to the Dinosauria ’ (Huxley, 1870 a: 30 – 31). Huxley also began, in this same article, to dismantle Cope’s classification of dinosaurs by pointing to anomalies in the leg and ankle structure among Cope’s ordinal varieties. Subsequently, Huxley (1870 b) reviewed and revised the classification of Dinosauria and, notwithstanding the primacy of Meyer’s (1832) name Pachypoda, grudgingly accepted Owen’s (1842) name Dinosauria: … it may be well to allow justice to give way to expediency, and to retain the name of Dinosauria for these reptiles. (Huxley, 1870 b: 33) Huxley, using an approach that strikes us today as singularly prescient, provided a list of 12 diagnostic characters shared by known dinosaurs. The dinosaurs, thus diagnosed, were then divided into three ‘ natural groups’ (given familial ranking): Megalosauridae, Scelidosauridae, Iguanodontidae – and he added to these a group differentiated from the previous three by referring to it as Compsognatha. Each of these groups was supported by a list of diagnostic anatomical characters. However, Huxley stressed that the taxon Compsognatha (not given a familial suffix) was distinct anatomically from the three other dinosaurian families by virtue of possessing a slender, elongated neck and cursorial hindlimb proportions. All these features were demonstrable in the nominal taxon Compsognathus. He concluded that it was necessary to create a new order of fossil reptiles that he named Ornithoscelida (because all of them exhibited bird-like limbs) and within this order he identified two suborders that he named Dinosauria (characterized by being short-necked and having stout graviportally adapted limbs) and Compsognatha (with long necks and slender cursorial limbs). Given that Huxley was dealing with just seven recognized dinosaur taxa, and how little of their anatomy was known, this work was remarkable. HUXLEY’ S (1870 B) CLASSIFICATION Order: ORNITHOSCELIDA Suborder: DINOSAURIA Family Megalosauridae Family Scelidosauridae Family Iguanodontidae Suborder: COMPSOGNATHA Nominal taxon Compsognathus Developing his concept of ornithoscelidans by c o m p a r i n g t h e m t o o t h e r t h e n - k n o w n r e p t i l e groups, Huxley introduced a confusing set of alleged affinities (= relationships) that resulted in his creating further higher level taxonomic groupings based upon vertebral column morphology alone. These superordinal categories – Suchospondylia, Erpetospondylia, Pleurospondylia and Perospondylia – were neither acknowledged nor formally adopted by contemporary taxonomists and systematists and – perhaps fortunately – went the way of Cope’s ill-fated Orthopoda, Goniopoda and Symphopoda. During subsequent decades, a greater range and variety of better-preserved dinosaur fossils were discovered, largely as a result of the prodigious efforts of Cope and Othniel Charles Marsh in the United States, as well as Louis Dollo in Europe (Colbert, 1968; Desmond, 1975). A clearer but more complicated picture of the range and variety of dinosaurian anatomy and morphology began slowly to emerge. Marsh (1881, 1884, 1891, 1895) assembled, illustrated and defined groupings of dinosaurs whose names and general attributes are still recognized today: Theropoda, Sauropoda, Ornithopoda, Stegosauria and Ceratopsia. Harry Govier Seeley [1887 (1888)] also developed a utilitarian classification of dinosaurs that was based primarily upon pelvic morphology (using the term ‘ ischia’ to mean pelvis in an Aristotelian sense) and the presence of vertebral pneumatism. Seeley’s system divided all known dinosaurs into two fundamentally distinct groups that he named Saurischia and Ornithischia. The clear-cut anatomical differences accommodated Marsh’s groupings consistently and rationally, and were taken by Seeley to be so fundamental as to imply that Dinosauria per se was not a natural group (clade): Dinosauria has no existence as a natural group of animals, but includes two distinct types of animal structure with technical characters in common, which show their descent from a common ancestry rather than their close affinity. (Seeley (1887 [1888]: 170) And a little later (p. 171): I see no ground for associating these two orders in one group. SEELEY’ S (1887 [1888]) CLASSIFICATION Order: SAURISCHIA Suborder: Theropoda Suborder: Sauropoda Order: ORNITHISCHIA Suborder: Ornithopoda Suborder: Ceratopsia Suborder: Stegosauria Although there were fundamental disagreements concerning the monophyly or (Seeley’s preference) diphyly and even polyphyly of dinosaurs with respect to their origin from archosaurian predecessors (e. g. Romer, 1933, 1968; Charig et al., 1965; Bakker & Galton, 1974; Charig, 1982), Seeley’s fundamental classificatory scheme proved robust in the face of continuous discoveries of new dinosaur taxa. In a major cladistic review of the Archosauria, Gauthier (1986) finally established a consensus over the matter of the monophyly of the Dinosauria and one that incorporated Seeley’s two principal taxa as sister-taxa. It is only comparatively recently that the underlying topology of the constituent members of the clade Dinosauria has been challenged (Baron et al., 2017 b, c).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0815FFABE1747253FDC4E2E2.taxon	description	1. Wa l t e r C o o m b s ’ (1 9 7 1, 1 9 7 8 a) r e v i e w s o f Ankylosauria clarified and greatly improved our understanding of their anatomy, and offered a logical basis (through the listing of sets of anatomical characteristics – effectively synapomorphies) that established a classification for the As a measure of support for his stated position on the matter, Coombs was able to refer (using the note added in proof) to an account of Scelidosaurus (Thulborn, 1977), in which it was argued (incorrectly) that this dinosaur was ornithopodan rather than an ankylosaurian. The extent to which Coombs had been misled about the anatomy of Scelidosaurus reflects the want of a descriptive revision, rather than any shortcoming of his own. Many of the anatomical characters listed by Coombs (1978 a) in his review of the classification of Ankylosauria have been translated into characterstate formats in numerous subsequent numerical cladistic analyses. 2. Sereno (1986) summarized ornithischian relationships and provided synapomorphy lists to support the clade Thyreophora: Scutellosaurus + Scelidosaurus + Eurypoda). Five characters supported a more exclusive clade named Thyreophoroidea (Scelidosaurus + Eurypoda – see Fig. 38): (a) A sinuous dentary tooth row in lateral view. (b) A supraorbital bone forms the dorsal orbital margin. (c) Enlargement of the medial portion of the mandibular condyle. (d) A basisphenoid that is much shorter than the basioccipital. (e) Median palatal pterygovomerine keel.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0815FFABE1747253FDC4E2E2.taxon	description	However, it was noted that Scelidosaurus had not been described (by 2008), with the implication that characters and character-state codings may differ once its anatomy is known in greater detail. It was also admitted that the analysis involved the coding of supraspecific operational taxonomic units, e. g. Stegosauria and Ankylosauria, and that a fuller consideration of the phylogenetic position of Scelidosaurus would (ideally) require consideration of a range of individual eurypodan taxa. However, this was considered to be beyond the scope of their analysis. Overall, the analysis cast doubt upon the interpretation of Scelidosaurus as a stem ankylosaur (Norman, 1984 b; Carpenter, 2001). Constraining the resolved tree so that Scelidosaurus is positioned as the sister-taxon to Ankylosauria increased tree length by eight steps (among trees of 485 steps), but they did note that this was not a significantly worse explanation of the data (Templeton Test, P = 0.04 – 0.13). 9. Several more taxonomically restricted analyses of thyreophoran ornithischians have been undertaken since the work of Butler et al. (2008). The most relevant among these, because they incorporate Scelidosaurus, are Thompson et al. (2012), Arbour & Currie (2016 – with a supplementary by Arbour & Evans, 2017) and Wiersma & Irmis (2018) for Ankylosauria; and Maidment et al. (2008), Mateus et al. (2009), Maidment (2010) and Raven & Maidment (2017) for Stegosauria. All of these studies provide taxon lists, as well as detailed character descriptions and coding. The output of these latter sets of analysis differ markedly. For ankylosaurs, large numbers of equally most parsimonious trees (MPTs) were generated from data tables in which the codes assigned to characters were unweighted and unordered [4248 MPTs (52 taxa and 170 characters) – Thompson et al., 2012; 3030 MPTs (44 taxa and 177 characters) – Arbour & Currie, 2016]; and finally 21 MPTs [35 taxa (31 thyreophorans) and 293 characters – none of which were weighted, but 48 were ordered] – Wiersma & Irmis (2018). For stegosaurs, the datasets were smaller: Maidment et al. (2008) used just 18 taxa (11 of which were ingroup stegosaurs) and 85 characters, whereas the most recent analysis (Raven & Maidment, 2017) used 23 taxa (13 of which were ingroup stegosaurs) and 114 characters. In contrast to the ankylosaur analyses, some characters were assessed (a priori) and selectively weighted or ordered. This procedure generated respectively five, 41 and finally a single MPT, seemingly considerably better resolved. Thorough though the analytical processing of all these studies has been, they are, somewhat paradoxically, limited with respect to their consideration of basal taxa (including Scelidosaurus). As a consequence, in all instances but one (Wiersma & Irmis, 2018), Scelidosaurus occupies an entirely consistent position as the sister-taxon to Eurypoda. In each analysis, character lists are notable for their choice of codable anatomical characters intended to differentiate between a range of derived, but anatomically conservative and, in many instances, fragmentary / incomplete ingroup taxa (note, for example, the discussion in Thompson et al. 2012: 308 et seq. regarding the status of the clade Polacanthinae / Polacanthidae). The cumulative effect of scoring large numbers of derived characterstates is that it introduces substantial statistical bias within the dataset that results in the outgroup OTUs and / or ‘ basal’ taxa being scored ‘ absent’ / ‘ 0 ’ for large numbers of characters (e. g. Butler et al., 2008; Thompson et al., 2012, et seq.) despite the fact that these characters enable resolution between more derived taxa within the overall analysis; these particular issues are discussed in greater detail by Brazeau (2011). Interestingly, Wiersma & Irmis (2018) compared the results of their analysis with those achieved by Arbour & Currie (2016 – and its reworked and heavily pruned iteration: Arbour & Evans, 2017). They noted a profound lack of resolution among most nodosaurid and ankylosaurid taxa in the strict consensus tree, and that a degree of resolution was only achieved by calculating a 50 % majority rule consensus (which should not be used to explore phylogenetic relationships – Sumrall et al., 2001); and a maximum agreement subtree, which, although it identifies consistent phylogenetic structure common among the MPTs, also removes a large number of taxa and is inherently unstable (Wiersma & Irmis, 2018). Weirsma & Irmis’ trees also lack resolution, although this does not appear to be as severe as that evident in Arbour & Currie’s data. Both studies highlight weak levels of tree support, which point toward fundamental characterrelated problems (high levels of homoplasy and missing data for many taxa) in ankylosaur systematics.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0815FFABE1747253FDC4E2E2.taxon	description	• Anatomical characters were incorrectly identified and / or scored because so little detailed anatomy of these taxa was known. In the case of Scelidosaurus, despite the skeleton having been cleared of matrix, authors have until now been obliged to rely on the monographs of Owen (1861, 1863), a small amount of anatomy illustrated by Charig (1972) or, on rare occasions, brief examination of material in the collections of the Natural History Museum (e. g. Carpenter et al., 2013; Arbour & Currie, 2016). An illustrative example of this particular problem can be seen in the matrix created by Arbour & Currie (2016) in which ~ 50 out of a total of 177 characters were scored incorrectly for Scelidosaurus; this observation has no bearing on the competence of these authors but simply reflects how little was then known of this important taxon. NEW ANALYSIS For the present analysis, the author surveyed, assessed and sampled previously published character lists and their codings, then constructed a matrix of 15 taxa and 115 characters (Supporting Information, Appendix S 2). The approach used was to identify characters that could be scored for currently known early (or apparently anatomically basal) taxa, as well as some exemplar well-preserved and well-described stegosaurs and ankylosaurs (see Supporting Information, Appendix S 2). This resulted in the production of a near equal split between cranial and postcranial characters (cranial 55: 60 postcranial). A number of characters were added, whereas others were redefined, corrected and re-coded. This process of winnowing avoided the incorporation of many highly specific characters that have no relevance to a consideration of basal taxon systematics (Brazeau, 2011). ANALYTICAL PROTOCOLS	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A086BFFD2E0AE703EFA92E7CA.taxon	description	The possibly node-based definition: The common ancestor of Stegosauria (Stegosaurus) and Ankylosauria (Euoplocephalus and Edmontonia) and all of its descendants, is exclusive and risks leading to the generation of new taxonomic names for stem-lineage thyreophorans when they have been discovered – or currently known taxa are re-positioned there following revision / updating.] Total characters under ACCTRAN 17, DELTRAN 12 – (see Supporting Information, Appendix S 3 for details): 1. Anterior supraorbital (palpebral) bound to the anterodorsal orbital margin. 2. Postorbital (and posterodorsal orbit margin) obscured by osteoderm (s). 3. Mandibular condyles of the quadrate: medial condyle larger than the lateral. 4. Median vomeropterygoid keel is deep (approaching or touching snout roof). 5. Dorsal margin of the dentary in occlusal view mildly bowed medially. 6. Fourth trochanter positioned at midlength on the femoral shaft. 7. Transverse width of the distal femur greater than the depth of the medial condyle. 8. Osteoderms form parasagittal rows either side of the dorsal midline. 9. Osteoderms extend along the caudal series.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A086BFFD3E3167616FEDFE72D.taxon	description	1. Quadrate head rectangular. 2. Pterygoids partially fused along the midline. 3. Maxillary and dentary crown surfaces bear long, vertical ridges. 4. Scapula blade stout and parallel-sided (homoplastic: also present in derived ankylosaurs). 5. Lateral profile of the ilium bowed dorsally (homoplastic: also present in derived ankylosaurs). 6. Postacetabular blade less than 30 % of the length of the ilium (homoplastic: also present in derived ankylosaurs). 7. Supraacetabular crest projecting laterally and creating a partially laterally open cupola. 8. Pubis, the femoral articular surface forms a laterally facing oval depression. 9. Pubic shaft stout and bar-shaped. 10. Femur tall, narrow and straight-shafted. 11. Femoral anterior trochanter exhibits partial fusion with the greater trochanter (homoplastic in some nodosaurids). 12. Femoral 4 th trochanter forms a raised ridge (homoplastic: present also in basal ankylosaurs and nodosaurids). 13. Cnemial crest of tibia robust and curved (homoplastic: present in derived ankylosaurs). 14. Fibula stout, but smaller than the tibia (homoplastic: present in derived ankylosaurs). 15. Pedal digit 1 lost. 16. Parasagittal midline osteoderms form hypertrophied plates or spines. 17. Lateral flank osteoderms are absent (except for parascapular spines). One row of lateral flank osteoderms has been reported in Huayangosaurus (Sereno & Dong, 1992: 340) but they reference an indistinct fieldwork photograph (Zhou, 1984: pl. 1) of a partial articulated skeleton. I have been unable to identify these osteoderms, and none were mounted on the skeleton in plate 13. 18. Distal caudal osteoderms form tall, paired conical spines. 19. Parascapular spine present (secondarily lost in stegosaurines).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A086AFFD3E09C7285FB17E22C.taxon	description	Kunbarrasaurus and Jinyunpelta: 1. Skull shape in occipital view, long-axis horizontal. 2. Premaxilla edentulous (homoplastic: among Nodosauridae, Ankylosauridae and Stegosauria). 3. Premaxillary palate wider than long. 4. Median marginal premaxillary notch present. 5. Postorbital, posterodorsal orbit margin obscured by osteoderms. 6. Predentary shape in occlusal view: extreme transverse extension to form a horizontal bar. 7. Mandibular glenoid ventrally offset relative to the occlusal plane of the dentition. 8. Long shallow symphyseal ramus of the mandible. 9. Premaxillary tooth count reduced to zero (reversed in some nodosaurids). 10. Scapula blade shape: stout and parallel-sided (homoplastic: Stegosauria). 11. Acetabular medial wall forms an imperforate cupola. 12. Femoral shaft shape in anterior view: stout and straight shaft. 13. Femoral anterior trochanter: completely fused to the greater trochanter (reversed in Kunbarrasaurus and Struthiosaurus). 14. Fourth trochanter has the form of a raised ridge (rather than being pendent, or a depression in the femoral shaft) – homoplastic in Stegosauria. 15. Cnemial crest of tibia is large and curved (homoplastic in Stegosauria). 16. Fibula smaller than tibia, but is a robust bone (homoplastic in Stegosauria).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A086AFFD3E09C77FBFE11E281.taxon	description	2. Proportions of metacarpal 1 ‘ medium’ (neither elongated nor squat).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A086AFFD3E09C70B4FD74E050.taxon	description	2. Skull has some additional (non-supraorbital) osteoderms. 3. Partial cortical remodelling of the skull surface present and includes a small number of osteoderms. 4. Postorbital has a medial wall that partitions the orbit from the adductor chamber. 5. Prominent exostosis on the lateral surface of the mandible, but an overlying osteoderm may not be present (unless the holotype mandibles preserve remnants of a superficially placed osteoderm).	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A086AFFD0E30470B9FD91E7F5.taxon	description	Total characters under ACCTRAN 16, DELTRAN 28) – additional to the previous listing: 1. External surface of the skull covered extensively by a ‘ carapace’ formed by interconnected osteoderms in fully mature individuals. 2. Quadrate shaft anteroventrally inclined. 3. Paroccipital processes oriented posteroventrolaterally. 4. Discrete and large, ridged osteoderm present on the lateral surface of the mandible. 5. Lateral profile of the dorsal surface of the ilium long and bowed dorsally. 6. Preacetabular process of the ilium expanded distally. 7. Shaft of the ischium rod or bar-shaped. 8. Obturator foramen / process absent. 9. Pubis fused to the ilium (and ischium). 10. Pubic shaft reduced to a small finger-shaped process (or entirely absent). 11. Pubic shaft considerably shorter than that of the ischial shaft. 12. Pedal ungual phalanges broadly rounded, flattened (hoof-like). 13. Conical lateral flank osteoderms.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0869FFD0E0AE7647FE8AE2A4.taxon	description	1. Maximum skull width equal to or greater than skull length. 2. Presence of paranasal fossae on the premaxilla. 3. Number of discrete antorbital osteoderms (caputegulae) greater than ten. 4. Skull roof osteoderms (caputegulae) have the form of small mostly rounded plates. 5. Lateral (infra) temporal fenestra occluded by osteoderms. 6. Femoral head terminally positioned on the femoral shaft. 7. Fourth trochanter of the femur is low-mound that surrounds a depressed muscle scar. 8. Fourth trochanter positioned on the distal half of the femoral shaft. 9. Distal tibia and proximal tarsals fused together. 10. Terminal caudal osteoderms combine to form a bony club.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
B66BDD2A0869FFD0E0AE711EFDD4E14D.taxon	description	1. Skull profile in lateral view arched or domed posterior to the orbit, creating the appearance of ventral flexure. 2. Occipital condyle hemispherical and separated from the braincase by a constricted neck. 3. Basisphenoid and pterygoids fused together. 4. Quadrate head fused to the squamosal-paroccipital. 5. Lateral (infra-) temporal fenestra reduced to a narrow slit. 6. Maxillary and dentary crowns possess welldeveloped cingula. 7. Acromial process of the scapula twisted laterally. 8. Ischial shaft with a pronounced bend at midlength. 9. Lateral cervicopectoral osteoderms develop into tall, conical-subconical plates or spikes.	en	Norman, David B (2021): Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society 191 (1): 1-86, DOI: 10.1093/zoolinnean/zlaa061, URL: https://academic.oup.com/zoolinnean/article/191/1/1/5893854
