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Iguanodonts from the Wealden of England: do they contribute to the discussion concerning hadrosaur origins?
... Digit impressions were counted using Roman numerals, but when recognition of a left or right track was not possible, digits were counted clockwise using Arabic numerals. Manus characters used for trackproducer identification are based on the studies of Norman (1980), Norman et al. (2014), Norman (2014), Brett-Surman and Wagner (2007, and Prieto-Marquez (2007. The term 'palmar' is used to describe the manus track in caudal view. ...
... Digit impressions were counted using Roman numerals, but when recognition of a left or right track was not possible, digits were counted clockwise using Arabic numerals. Manus characters used for trackproducer identification are based on the studies of Norman (1980), Norman et al. (2014), Norman (2014), Brett-Surman and Wagner (2007, and Prieto-Marquez (2007. The term 'palmar' is used to describe the manus track in caudal view. ...
... This group underwent a striking evolutionary radiation during the Mesozoic, and by the end of the Cretaceous became one of the most successful herbivorous groups on land (Strickson et al. 1932). Important adaptations reflecting their evolutionary success involved the masticatory apparatus and the appendicular skeleton, among others (Norman et al. 2014;Butler and Barrett 2012). The manus in particular shows significant anatomical and biomechanical changes ( Figure 2). ...
Hadrosauriformes is a group of ornithopod dinosaurs with a rich and extensive Cretaceous track record. However, their rear foot (pes) anatomy is rather conservative. Thus, distinguishing different putative track producers from morphological differences is often impeded unless their identification is corroborated by stratigraphic and geographic distribution. On the contrary, the forefoot (manus) anatomy of hadrosauriform taxa reflects distinctive characters that, when preserved in tracks, may be critical for identifying their trackmakers. In this study, we examined three manus tracks preserved as sandstone casts, collected from Coniacian deposits of the Frontier Formation, southwestern Montana, USA. Tracks are assigned to Hadrosauriformes according to their steeply inclined morphology, functionally tridactyl condition, presence of hoof-like impressions and crescentic cross-sectional shape. Track preservation suggests that digit II could be extended medially, whereas movements for digits III and IV were limited. The dorsally curved digit II and III impressions indicate that these digits could be hyperextended. One track shows a short, spade-like ungual II impression, suggesting a closer affinity of its producer to hadrosauroid or hadrosaurid ornithopods. Osteological characters of the manus combined with track morphology can help with discerning different hadrosauriform producers, providing important implication for palaeoecological and palaeogeographical reconstructions.
... Valanginian large styracosternans comprises Barilium dawsoni [44] and Hypselospinus fittoni [12] from England. Other taxa from this age are considered nomina dubia or subjective synonyms of Barilium or Hypselospinus [45,46]. ...
... Iguanodon bernissartensis and Mantellisaurus atherfieldensis are known from several sites in Europe and probably coexisted [32]. Other taxa from the middle Barremian-early Aptian are considered nomina dubia or synonyms of Iguanodon and Mantellisaurus [45,46]. ...
... Sites: In the Lower Cretaceous of Europe, specifically in Germany, Belgium, Spain, France, and the United Kingdom [7,9,10,32,37,45,46]. ...
A new styracosternan ornithopod genus and species is described based on the right dentary of a single specimen from the Mirambell Formation (Early Cretaceous, early Barremian) at the locality of Portell, (Castellón, Spain). Portellsaurus sosbaynati gen. et sp. nov. is diagnosed by two autapomorphic features as well as a unique combination of characters. The autapomorphies include: the absence of a bulge along the ventral margin directly ventral to the base of the coronoid process and the presence of a deep oval cavity on the medial surface of the mandibular adductor fossa below the eleventh-twelfth tooth position. Phylogenetic analyses reveal that the new Iberian form is more closely related to the African taxon Ouranosaurus nigeriensis than to its synchronic Iberian taxa Magnamanus soriaensis and Iguanodon galvensis . In addition, Portellsaurus sosbaynati is less related to other Iberian taxa such as Iguanodon bernissartensis and Proa valdearinnoensis than to the other Early Cretaceous Iberian styracosternans Mantellisaurus atherfieldensis and Morelladon beltrani . A new phylogenetic hypothesis is proposed that resolves Iguanodon ( I . bernissartensis , I . galvensis ) with the Valanginian Barilium dawsoni into a monophyletic clade (Iguanodontoidea). The recognition of Portellsaurus sosbaynati gen. et sp. nov. as the first styracosternan dinosaur species identified from the Margas de Mirambell Formation (early Barremian–early late Barremian) in the Morella sub-basin (Maestrat Basin, eastern Spain) indicates that the Iberian Peninsula was home to a highly diverse assemblage of medium-to-large bodied styracosternan hadrosauriforms during the Early Cretaceous.
... Hulke (1882) reports fossils (syntype material of 'I. seelyi') from the Wessex Formation (upper Barremian-lower Aptian) of the Isle of Wight (United Kingdom) considered referable to I. bernissartensis (Norman 2014). Sanz et al. (1982), and Gasulla et al. (2007Gasulla et al. ( , 2010Gasulla et al. ( , 2011Gasulla et al. ( , 2014 refer several fossils from the Morella Formation (upper Barremian) of Morella (Spain) to I. bernissartensis. ...
... RBINS R51, holotype), Ouranosaurus (Taquet 1976 (Langston 1960). However, the curvature of the ischiatic shaft seems variable both in I. bernissartensis ) as well as in Mantellisaurus; RBINS R57 has a straight ischium, whereas certain other specimens show a gently curved ischium (Norman 2014). The ischiatic shaft has a D-shaped cross section in I. galvensis, unlike the triangular cross-section in I. bernissartensis (e.g. ...
... Valanginian large styracosternans comprises Barilium dawsoni (Norman 2011a) and Hypselospinus fittoni (Norman 2015) from England. Several other taxa from the Valanginian -'Iguanodon hollingtoniensis' (Lydekker 1889), 'Torilion' dawsoni, 'Sellacoxa pauli', 'Wadhurstia' fittoni (Carpenter & Ishida 2010), 'Kukudelfia tilgatensis' (McDonald, Barrett, et al. 2010), 'Huxleysaurus hollingtoniensis' , and 'Darwinsaurus evolutionis' (Paul 2012)are currently considered nomina dubia or subjective synonyms of Barilium or Hypselospinus (Norman 2013(Norman , 2014. On the other hand, the early Barremian is characterized by the presence of 'Delapparentia turolensis' (Ruiz-Omeñaca 2011) and I. galvensis both taxa that are described from Spain; nevertheless, Norman (2015) considers 'Delapparentia' a potential nomen dubium. ...
Iguanodon galvensis is the second valid species in the European and Barremian large-ornithopod genus Iguanodon. In the present work, the I. galvensis holotype and referred material from the lower Barremian of Spain are described and discussed in detail. As a result, emended diagnoses of Iguanodon, I. galvensis and I. bernissartensis are proposed; I. galvensis can now be identified by three autapomorphies in the dentary, ischium and femur as well as a unique combination of characters. Moreover, I. galvensis is compared with other European Early Cretaceous large styracosternans. Finally, a new phylogenetic hypothesis is proposed that resolves Iguanodon (I. bernissartensis, I. galvensis) with the Valanginian Barilium dawsoni into a monophyletic clade (Iguanodontoidea).
... Iguanodon is among the best known of Europe's ornithopod genera; more than 30 complete and partial skeletons have been recovered from the Lower Cretaceous (upper Barremian-Aptian) of Belgium, England, France, Germany and Spain (Norman, 2014a). Currently, Iguanodon contains a single species, Iguanodon bernissartensis Boulenger in Van Beneden 1881 (Norman, 2014a). ...
... Iguanodon is among the best known of Europe's ornithopod genera; more than 30 complete and partial skeletons have been recovered from the Lower Cretaceous (upper Barremian-Aptian) of Belgium, England, France, Germany and Spain (Norman, 2014a). Currently, Iguanodon contains a single species, Iguanodon bernissartensis Boulenger in Van Beneden 1881 (Norman, 2014a). Although its fossil record is extensive, many features of its biology remain unclear, particularly those pertaining to the first stages of development. ...
... A comparison is also made with "I. seelyi" (Hulke, 1882;Norman, 2012), a junior synonym of I. bernissartensis (Norman, 2014a). ...
Although Iguanodon is one of the most abundant and well-known of Europe's dinosaur genera, fossils of young specimens are very rare. Indeed, the fossil record contains very few examples of the young of any non-hadrosaurid iguanodontian. Here we report the discovery of 13 Iguanodon perinates from the Lower Cretaceous of Galve (Teruel, Spain). The characteristics of an adult and juvenile found nearby show these perinates to belong to a new species: Iguanodon galvensis sp. nov. The histological and osteological features of these young animals indicate them to have been in their first year of life. The taphonomic features of their remains, plus the finding of clearly embryonic vertebrae alongside them, suggest the perinates of this species remained in the vicinity of their nests for some time, possibly congregating in nursery areas.
... Rhabdodontidae (Weishampel et al., 2003;Osi et al., 2012), tenontosaurs (Butler, Upchurch & Norman, 2008), Dryosauridae (Barrett et al., 2011), and Camptosaurusgrade taxa (McDonald, 2011(McDonald, , 2012a. Anatomically more derived ornithopods, referred to as hadrosauromorphans (Norman, 2014), were also considered as part of the analysis because they represent an evolutionary continuation of the iguanodontian lineage. Finally, taxonomic names that have been created recently and applied to Wealden-aged iguanodont material have been assessed so that they can be excluded from further consideration (Norman, 2013). ...
... Digit I of the manus is not present (in striking contrast to Hy. fittoni). The ilium has a strongly everted dorsal margin in the region posterodorsal to the ischiadic peduncle; this area rather than forming a bevelled thickening is developed into a pendant, tab-like structure referred to as a pendule (Norman, 2014). The postacetabular process of the ilium forms a flat rectangular plate with the brevis fossa (if present) restricted to its medial surface. ...
... The specimens, a maxilla plus articulated lacrimal and an edentulous dentary, were not associated and show evidence of post-mortem distortion, which may have contributed to the way in which its anatomy has been described and interpreted. In systematic analyses You et al. (2003a) placed this taxon as the sister taxon to the Hadrosauridae (= Euhadrosauria sensu Weishampel et al., 1993;Norman, 2014) and McDonald (2012b) placed it at just one further step removed. ...
The history of discovery and interpretation of several dinosaurs collected from quarries near the town of Hastings during the latter half of the 19th century is more complicated than it should be. Samuel Husbands Beckles and Charles Dawson collected several large ornithopod skeletons from this area, but just a few bones from these skeletons were subsequently described and interpreted (principally) by Richard Owen and Richard Lydekker. All these specimens merited recognition because they had the potential to contribute to an on-going debate about the anatomical structure and relationships of the iconic Wealden dinosaur Iguanodon. Unfortunately, no detailed description of these important skeletons was published in later years. Furthermore, previously known associations of bones and even provenance information, linked to the specimens that were gradually acquired by the Natural History Museum, are unclear. Confusion may have arisen because Richard Lydekker used the private collector Charles Dawson as a voluntary curatorial assistant. This account documents the past work on the osteology of material that can be attributed to Hypselospinus fittoni. Nearly all such material is described here for the first time, and every effort has been made to re-establish associations between bones as well as provenance information. A skeletal reconstruction of Hypselospinus is attempted on the basis of the hypodigm. Most of the on-going confusion concerning the affinity of this material with either Hy. fittoni or its sympatric contemporary Barilium dawsoni has been resolved. Hypselospinus fittoni (Lydekker, 1889) is rediagnosed on the basis of this new and relatively comprehensive anatomical description, and this animal is compared with known contemporary and closely related taxa. Some recently published accounts claiming to be revisions of the taxonomy of Wealden ‘iguanodonts’, including material belonging to the hypodigm of Hy. fittoni, have failed to adhere to basic taxonomic principles and have caused more confusion than was strictly necessary. The systematic position of Hypselospinus is reassessed cladistically. The cladistic analysis forms the basis for a revised hierarchical classification of derived ornithopods. The consensus topology generated by the systematic analysis has been used to explore the phylogenetic history of these dinosaurs and create an internally consistent classificatory hierarchy (phylogenetic definitions and Linnaean diagnoses are given for critical positions in the topology). This analysis suggests that there is a fundamental split amongst the more derived (clypeodontan) ornithopod ornithischians into the clades Hypsilophodontia and Iguanodontia. There is evidence for anatomical parallelism and convergence (homoplasy) particularly between large-bodied representatives of both clades. Hypselospinus is one of the earliest known styracosternan iguanodontians and displays anatomical characteristics that presage the evolution of the extraordinarily abundant and diverse hadrosaurs of the latest Cretaceous (Campanian−Maastrichtian). These observations cast fresh light on the phylogeny, classification, diversity, and biology of derived ornithopods. There is little doubt that Hy. fittoni could have been understood far better more than a century ago. That this statement is undoubtedly true is reflected in the century of doubt and confusion that has surrounded this taxon and its original incarnation as Iguanodon fittoni. © 2014 The Linnean Society of London
... In relation to their size, the centra of CM-3 and CM-8 are comparable with the vertebrae of other large ornithopods of the Lower Cretaceous of Europe. The anterior dorsal centrum MAP-8038 of CM-3 is longer (97 mm) than the first and second dorsal vertebrae of specimen RBINS 1551 of the medium-sized styracosternan Mantellisaurus atherfieldensis (68 and 70 mm respectively, Norman, 1986) estimated to be 6.5 m long (Norman, 2014). The middle dorsal centra MAP-8044 of CM-8 and MAP-8037 of CM-3 show a length (95 and 93 mm, respectively) similar to that of their homologous vertebrae in specimen RBINS 1534 of the large-sized styracosternan Iguanodon bernissartensis (6th and 10th dorsal, 93 and 98 mm respectively; Norman, 1980Norman, , 1986 which was roughly 8-10 m long (Norman, 2014;Paul, 2008), but both are slightly shorter than the equivalent vertebrae of a mature specimen of Iguanodon cf. ...
... The anterior dorsal centrum MAP-8038 of CM-3 is longer (97 mm) than the first and second dorsal vertebrae of specimen RBINS 1551 of the medium-sized styracosternan Mantellisaurus atherfieldensis (68 and 70 mm respectively, Norman, 1986) estimated to be 6.5 m long (Norman, 2014). The middle dorsal centra MAP-8044 of CM-8 and MAP-8037 of CM-3 show a length (95 and 93 mm, respectively) similar to that of their homologous vertebrae in specimen RBINS 1534 of the large-sized styracosternan Iguanodon bernissartensis (6th and 10th dorsal, 93 and 98 mm respectively; Norman, 1980Norman, , 1986 which was roughly 8-10 m long (Norman, 2014;Paul, 2008), but both are slightly shorter than the equivalent vertebrae of a mature specimen of Iguanodon cf. galvensis, 9-10 m long (e.g. ...
The El Castellar Formation (upper Hauterivian-lowermost Barremian, Lower Cretaceous) in the southwest of the Maestrat Basin (Spain) has yielded diverse dinosaur remains, mostly fragmentary bones. This study describes, morphometrically analyses, and compares several isolated postcranial fossils of large ornithopods from three new different sites in the municipality of Cabra de Mora (Peñagolosa sub-basin, Teruel Province). The fossils are attributed to styracosternan ornithopods, and some of them are related to the species Iguanodon galvensis, representing the oldest known record related to this taxon in the Iberian Peninsula. Moreover, this study verifies the hypothesis of the coexistence of at least two different styracosternans—a medium-sized form and a large-sized one—during the late Hauterivian-early Barremian in the Peñagolosa sub-basin. In addition, we formally describe the first dinosaur tracksite of the El Castellar Formation in this sub-basin. All ichnites are preserved as natural casts, and their trackmakers are likely to have been related to large styracosternans. Hence, the evidence provided here by both bones and tracks supports the idea that large ornithopods were the predominant dinosaurs in the wetlands of an extensive coastal plain.
... The use of the name Clypeodonta differed across studies. Originally, Norman (2014Norman ( , 2015 intended to use it for a subclade of Ornithopoda that (approximately) comprises Hypsilophodon foxii and its relatives, and ornithopods later-diverging than H. foxii, and (informally) defined the name as pertaining to either, the branch of "Parasaurolophus walkeri and all taxa more closely related to P. walkeri than to Thescelosaurus neglectus" (Norman, 2014: 29) or the node of "Hypsilophodon foxii, Edmontosaurus regalis, their most recent common ancestor, and all of its descendants" (Norman, 2015: 170). In both these studies, Clypeodonta is said (Norman, 2014: 29) or figured (Norman, 2015: Fig. 50) to cover the same known contents although neither of the studies included taxa in their analyses that would fall outside the clade (except for Lesothosaurus diagnosticus). ...
... Here we define the name Clypeodonta using the minimum-clade definition of Norman (2015). However, by including the part "within Ornithopoda" in the definition, we restrict the use of Clypeodonta only when H. foxii represents an ornithopod (see Article 11.14 of the ICPN), following the original intent of Norman (2014Norman ( , 2015. Composition. ...
Ornithischians form a large clade of globally distributed Mesozoic dinosaurs, and represent one of their three major radiations. Throughout their evolutionary history, exceeding 134 million years, ornithischians evolved considerable morphological disparity, expressed especially through the cranial and osteodermal features of their most distinguishable representatives. The nearly two-century-long research history on ornithischians has resulted in the recognition of numerous diverse lineages, many of which have been named. Following the formative publications establishing the theoretical foundation of phylogenetic nomenclature throughout the 1980s and 1990s, many of the proposed names of ornithischian clades were provided with phylogenetic definitions. Some of these definitions have proven useful and have not been changed, beyond the way they were formulated, since their introduction. Some names, however, have multiple definitions, making their application ambiguous. Recent implementation of the International Code of Phylogenetic Nomenclature (ICPN, or PhyloCode) offers the opportunity to explore the utility of previously proposed definitions of established taxon names. Since the Articles of the ICPN are not to be applied retroactively, all phylogenetic definitions published prior to its implementation remain informal (and ineffective) in the light of the Code. Here, we revise the nomenclature of ornithischian dinosaur clades; we revisit 76 preexisting ornithischian clade names, review their recent and historical use, and formally establish their phylogenetic definitions. Additionally, we introduce five new clade names: two for robustly supported clades of later-diverging hadrosaurids and ceratopsians, one uniting heterodontosaurids and genasaurs, and two for clades of nodosaurids. Our study marks a key step towards a formal phylogenetic nomenclature of ornithischian dinosaurs.
... In the second femur referred to Ar. ardevoli (incomplete specimen MPZ 2008/337), the extensor groove is apparently closed (Cruzado-Caballero et al., 2013, p. 1378. (2015) while, in fact, the name first appeared in Norman (2014). Originally, Clypeodonta was defined as a branch-based name using Parasaurolophus walkeri as an internal specifier and Thescelosaurus neglectus as an external specifier. ...
... To name a just few: Allosauria and Carcharodontosauria are sub-clades of Allosauroidea (e.g., Benson et al., 2010;Carrano et al., 2012), while Brachyrostra and Furileusauria are sub-clades of Abelisauridae (Canale et al., 2008;Filippi et al., 2016), and Eucentrosaura and Pachyrostra are sub-clades of Centrosaurinae (Fiorillo and Tykoski, 2012). Others include Pantyrannosauria and Eutyrannosauria as sub-clades of Tyrannosauroidea (Delcourt and Grillo, 2018), Megalosauria as a sub-clade of Megalosauroidea (Carrano et al., 2012), Eudromaeosauria as a sub-clade of Dromaeosauridae (Longrich and Currie, 2009) and Hadrosauromorpha as a sub-clade of Hadrosauroidea (Norman, 2014). ...
Ornithopod dinosaurs were abundant inhabitants of European islands during the Late Cretaceous. The long history of dinosaur research in Europe has led to the establishment of new taxa for numerous ornithopod specimens that received considerable attention in the literature; however, many of these remain essentially unstudied. This explains why little is known of their potential phylogenetic, ecological and biogeographical importance. Here we provide a reassessment of Orthomerus dolloi, an enigmatic ornithopod taxon that was established on the basis of isolated appendicular elements, including a left tibia, a right femur, a left femur and a metatarsal. The material originates from the uppermost Maastrichtian of southern Limburg (the Netherlands) or adjacent Belgian territory. Despite the fact that they have been known for almost 140 years, none of these elements has been evaluated in detail since their original description. Here we redescribe and illustrate the syntypes of O. dolloi, and compare them to corresponding elements in other latest Cretaceous ornithopods from Europe. The character distribution in O. dolloi is further explored by means of phylogenetic analyses, using a revised ornithopod-wide dataset. The material belongs to at least two, probably conspecific, individuals that show clear hadrosauroid affinities, although the exact placement of the taxon within the clade remains contentious, because it is likely that its elements are osteologically immature. Therefore, the common assignment of O. dolloi to hadrosaurid ornithopods is questionable. Nevertheless, our revision of the material has not identified any autapomorphies, nor a combination of characters that would be indisputably unique among Hadrosauroidea.
... Hadrosauromorphs (sensu Norman [82]) were likely widely distributed across Laurasia in the middle Cretaceous, and the generally poor resolution of this phylogenetic analysis makes biogeographic inferences difficult. Centers of origin and faunal interchange in other dinosaurs between the Asia and North America may also prove to be more complex than previously considered (e.g., [83][84][85]), and these types of inferences, whether between Asia and North America or involving other landmasses, clearly benefit from a phylogenetic perspective (e.g., [30,[86][87][88][89][90]). ...
A new genus and species of non-hadrosaurid hadrosauroid, Gobihadros mongoliensis, is described from a virtually complete and undeformed skull and postcranial skeleton, as well as extensive referred material, collected from the Baynshire Formation (Cenomanian-Santonian) of the central and eastern Gobi Desert, Mongolia. Gobihadros mongoliensis is the first non-hadrosaurid hadrosauroid from the Late Cretaceous of central Asia known from a complete, articulated skull and skeleton. The material reveals the skeletal anatomy of a proximate sister taxon to Hadrosauridae in remarkable detail. Gobihadros is similar to Bactrosaurus johnsoni and Gilmoreosaurus mongoliensis, but can be distinguished from them in several autapomorphic traits, including the maximum number (three) of functional dentary teeth per tooth position, a premaxillary oral margin with a ‘double-layer morphology’, and a sigmoidal dorsal outline of the ilium with a well-developed, fan-shaped posterior process. All of these characters in Gobihadros are inferred to be convergent in Hadrosauridae. Phylogenetic analysis positions Gobihadros mongoliensis as a Bactrosaurus-grade hadrosauromorph hadrosauroid. Its relationship with Maastrichtian hadrosaurids from Asia (e.g., Saurolophus angustirostris, Kerberosaurus manakini, Wulagasaurus dongi, Kundurosaurus nagornyi) are sufficiently distant to indicate that these latter taxa owe their distribution to migration from North America across Beringia, rather than having a common Asian origin with Go. mongoliensis.
... Other publications on ornithopods include a series of papers on the Bernissart dinosaurs and Early Cretaceous terrestrial ecosystems (Godefroit, ed., 2012). One of these is by Norman (2012), who summarized the history, anatomy and taxonomy of British and Norman (2014) discussed the contribution of Wealden iguanodonts to hadrosaur origins, and followed this with a comprehensive paper on the history, osteology and systematic position of the iguanodontian dinosaur Hypselospinus fittoni (Norman, 2015). discussed new material of the ornithopod dinosaur Valdosaurus canaliculatus from the Wessex Formation on the Isle of Wight and the Grinstead Clay Formation in West Sussex. ...
The non-marine Wealden succession of southern England contains a great variety of fossils, new finds of which continue to reveal novel insights into the animals and plants that inhabited this part of the world during much of the Early Cretaceous. Although seldom common, careful searching during the past few years has yielded megafossils that add to previous knowledge of occurrences of taxa and palaeoenvironmental conditions. Particularly significant in this respect has been the recovery of a large number of new insect species, but there have also been numerous finds of vertebrate bones and other body parts, such as teeth, skulls, a claw and a cranial endocast. In addition, the taxonomy of some of these groups and, in the case of dinosaurs, the ichnotaxonomy of their footprints and trackways, has been reviewed and/or reassessed. In this paper, we provide an illustrated account of the research that has been published on Wealden geology and the fossils that have been recovered from the succession since a field guide to English Wealden fossils was issued by the Palaeontological Association in 2011. It is aimed at providing the reader with a document of first resort for fossil identification purposes and a lead into the literature for further information
... In Gasparinisaura the posterior process of the jugal is greatly reduced and dorsally displaced, allowing the anterior process of the L-shaped quadratojugal to contact the ventral part of the posterior margin of the jugal body ( Coria and Salgado, 1996). In most clypeodontans (sensu Norman, 2014Norman, , 2015) the posterior end of the posterior process of the jugal forms a distinct, dorsally directed flange that extends along the anterior margin of the quadratojugal, makes a large contribution to the posterior margin of the infratemporal fenestra, and may contact the quadrate above the dorsal end of the quadratojugal. In the rhabdodontid Zalmoxes this quadratojugal flange is rounded, whereas in iguanodontians the flange characteristically tapers to a broad or narrow point. ...
In dinosaurs, as in other reptiles, the homologue of the mammalian zygomatic bone is the jugal. The dinosaurian jugal was primitively triradiate, with posterior, dorsal and anterior processes that respectively contacted the quadratojugal, the postorbital, and the maxilla and lacrimal. However, the jugal evolved along different lines in the three major dinosaurian clades. In theropods this cranial element remained relatively conservative in morphology, apart from being reduced to a rod-like structure in most birds and a few non-avians. In sauropodomorphs the jugal eventually became small, plate-like and nearly restricted to the area below the orbit, even being excluded from the ventral margin of the skull in many derived taxa. Among ornithischians the jugal was highly variable, but in many cases became large and/or adorned with ornamental features such as horns, flanges, and rugosities. The jugal does not appear to have been a site of muscle attachment in most non-avian dinosaurs, but represented an important structural element in the akinetic dinosaurian skull. The conspicuous jugal ornaments seen in many ornithischian dinosaurs, like the less striking ones documented in some saurischians, may have played an important role in the social behavior of the species that possessed them. In many cases they have a weapon-like aspect suggesting use in aggressive displays, if not actual combat, adding to the evidence that agonistic behavior was likely widespread among ornithischians in particular. Anat Rec, 300:30–48, 2017.
... Norman 1980Norman , 1986Norman , 2004) that iguanodontian dinosaurs had evolved a relatively complex range of locomotor skills and social behaviour patterns comparable with those suggested for their later Cretaceous descendants, the hadrosaurs (cf. Norman 2014Norman , 2015. Some hadrosaurs (which are ornithopods and whose range of EQs overlap, or slightly exceed, those of the example discussed here) are known to have exhibited complex nesting and brooding behaviours (Horner & Makela 1979) and to have structures in their skulls indicating that sound production, using cranially located resonating chambers (Weishampel 1981), may have played an important role in their Fig. 10. ...
It has become accepted in recent years that the fossil record can preserve labile tissues. We report here the highly detailed mineralization of soft tissues associated with a naturally occurring brain endocast of an iguanodontian dinosaur found in c. 133 Ma fluvial sediments of the Wealden at Bexhill, Sussex, UK. Moulding of the braincase wall and the mineral replacement of the adjacent brain tissues by phosphates and carbonates allowed the direct examination of petrified brain tissues. Scanning electron microscopy (SEM) imaging and computed tomography (CT) scanning revealed preservation of the tough membranes (meninges) that enveloped and supported the brain proper. Collagen strands of the meningeal layers were preserved in collophane. The blood vessels, also preserved in collophane, were either lined by, or infilled with, microcrystalline siderite. The meninges were preserved in the hindbrain region and exhibit structural similarities with those of living archosaurs. Greater definition of the forebrain (cerebrum) than the hindbrain (cerebellar and medullary regions) is consistent with the anatomical and implied behavioural complexity previously described in iguanodontian-grade ornithopods. However, we caution that the observed proximity of probable cortical layers to the braincase walls probably resulted from the settling of brain tissues against the roof of the braincase after inversion of the skull during decay and burial.
Supplementary material: Information regarding associated fossil material, and additional images, can be found at https://doi.org/10.6084/m9.figshare.c.3519984
The skull of the hadrosauroids is the most complex structure of its anatomy, with features of systematic and phylogenetic
importance. Recent discoveries have increased the anatomical diversity, causing confusion to recognize unique
characters or derivatives, by using different terms for the same structures. This situation is more complex when Spanish-
speaking researchers and students need to make a detailed description. This work represents the second part of the
anatomical guide of the hadrosauroids, which includes an updated and illustrated introductory compendium of their
cranial anatomy. The purpose is to facilitate the handling of new data of phylogenetic importance and the taxonomic
identification of isolated or associated remains, using morphotypes
Is an up-date review of the postcranial osteology of hadrosaurs
The basal hadrosauroid Tethyshadros insularis from the uppermost Cretaceous of NE Italy lived on an island of the European archipelago in the Tethys Ocean. The tail of this dinosaur presents several apomorphic traits respect to the tails of other coeval hadrosauroids of the archipelago and of hadrosauroids in general. The estimated total length of the tail of the holotypic specimen shows that the tail was long, accounting for at least 56% of the total body length, relatively stiff and deep proximally, whereas it was whip-like distally. The reconstruction of the tail musculature by comparison with that of living archosaurs and other dinosaurs suggests that the posterior shift of the first haemapophysis affected the size and shape of the M.m. caudofemorales with important consequences on the locomotion of T. insularis. Somewhat peculiar stance and gait for this dinosaur are suggested also by limb features. The posterior shift of the vent and consequent longer distal tract of the intestine or a longer cloaca could increase the space for urine storage and urinary water reabsorption. The posterior shift of the vent could imply also longer oviducts and plausibly an increased number of eggs per clutch. Tail apomorphies of T. insularis may be related to the rugged and water-depleted karst landscape where the Italian dinosaur lived. The two main specimens of T. insularis differ in robustness possibly because of sexual dimorphism, ontogeny or high intraspecific variability.
During the Early Cretaceous, dinosaur communities of the Australian-Antarctic rift system (Eumeralla and Wonthaggi formations) cropping out in Victoria were apparently dominated by a diverse small-bodied 'basal ornithopod' fauna. Further north, in Queensland (Winton and Mackunda formations), poorly-represented small-bodied ornithopods coexisted with large-bodied iguanodontians. Our understanding of the ornithopod diversity from the region between the Australian-Antarctic rift and Queensland, represented by Lightning Ridge in central-northern New South Wales (Griman Creek Formation), has been superficial. Here, we re-investigate the ornithopod diversity at Lightning Ridge based on new craniodental remains. Our findings indicate a diverse ornithopod fauna consisting of two-to-three small-bodied non-iguanodontian ornithopods (including Weewarrasaurus pobeni gen. et sp. nov.), at least one indeterminate iguanodontian, and a possible ankylopollexian. These results support those of previous studies that favour a general abundance of small-bodied basal ornithopods in Early to mid-Cretaceous high-latitude localities of southeastern Australia. Although these localities are not necessarily time-equivalent, increasing evidence indicates that Lightning Ridge formed a 'meeting point' between the basal ornithopod-dominated localities in Victoria and the sauropod-iguanodontian faunas in Queensland to the north. Subjects Paleontology, Taxonomy
Papers from the 4th G. Cuvier Symposium held on October 2012 in Montbéliard (Doubs, France): Fossils, Evolution and Movement.
The taxonomy of Wealden-aged iguanodontians is reviewed in the light of recent publications that indicate higher levels of taxonomic diversity existed compared to estimates from the recent past. Of the seventeen taxonomic names that have been suggested to date, four represent taxonomically valid morphological types: Barilium dawsoni, Hypselospinus fittoni, Iguanodon bernissartensis and Mantellisaurus atherfieldensis. The other thirteen taxonomic names are either objectively synonymous with one or other of the valid taxa, or are nomina dubia. The recent spate of taxonomic proposals appear to be driven by a belief that greater diversity must exist within the Wealden succession (Weald: Hastings and Weald Clay Groups; Wessex: Wealden Group) given that it spanned approximately 20 million years of geological time. However, critical evaluation of the actual material, and the stratigraphic levels from which specimens have been collected in the Wealden geological succession, confirms the imperfect nature of the fossil record. As a consequence fossil collectors have only been able to sample two comparatively time-restricted horizons: one in the middle Valanginian (~138-136 Ma), the other in the middle-upper Barremian-lowermost Aptian (~128-125 Ma). The plethora of new, yet invalid, taxonomic names suggests some inconsistency in the maintenance of standards associated with good taxonomic practice. The dangers inherent in allowing poor taxonomic practice to generate false measures of fossil diversity are outlined.
A nearly complete right dentary originally noted by Mantell in 1848 is redescribed. The specimen, NHMUK 28660, was discovered in a quarry near Cuckfield, West Sussex, from the same formation as the original teeth of Iguanodon anglicus. Fresh examination reveals that NHMUK 28660 exhibits a single autapomorphy (a row of foramina extending from the ventral surface of the symphysis onto the lateral surface of the dentary) and a unique combination of characters that distinguish it from all other iguanodontian dentaries. In light of this and because I. anglicus is regarded as a nomen dubium to which additional material cannot be unambiguously referred, NHMUK 28660 is made the holotype of the new genus and species Kukufeldia tilgatensis.
In traditional Linnaean taxonomy, classifications are constructed and maintained principally as dichotomous hierarchies. In phylogenetic taxonomy, such hierarchies are restricted to monophyletic groups defined explicitly on the basis of common ancestry. A definitional configuration termed a node-stem triplet is described that stabilizes the relationship between a given taxon and its subordinate taxa. I outline a rationale within phylogenetic taxonomy for construction of a stable taxonomic framework, as demonstrated by application to the higher-level taxonomy of Dinosauria.
Los recientes descubrimientos de diversos iguanodontes en la Formación Cedar Mountain (Utah, EE.UU.) nos han llevado a valorar la diversidad global de los iguanodontes del Cretácico temprano. El registro en Inglaterra es más diverso de lo que previamente se ha reconocido, debido a que Iguanodon ha sido tratado como un género ¿cajón de sastre¿ a lo largo de todo el siglo XX. Varios de los nuevos taxones, previamente reconocidos como genéricamente distintos por Harry Seeley Grovier, se denominan. La distribución espacial y temporal de Iguanodontia se superponen sobre mapas globales como una clave para comprender el origen de los iguanodontes de la Formación Cedar Mountain.
Hadrosaurus foulkii was the first dinosaur known outside Europe from partially complete skeletal elements. It is the holotype of the family Hadrosauridae and the subfamily Hadrosaurinae. The history of its discovery and taxonomy is reviewed, and the holotype of H. foulkii is redescribed. The holotype of H. foulkii lacks distinguishing characters; therefore, this taxon is a nomen dubium. It is not synonymous with species of Gryposaurus and/or Kritosaurus. We also reevaluate the taxonomy and osteology of H. tripos, H. minor, H. cavatus, H. breviceps, H. paucidens, and Ornithotarsus immanis. In agreement with previous studies, these taxa are considered nomina dubia due to the absence of distinguishing characters and are therefore referrable only to Hadrosauridae indeterminate; H. paucidens is referrable to Lambeosaurinae indeterminat e. Finally, our phylogenetic analysis indicates that the holotype of H. foulkii belongs to a member of Euhadrosauria and, tentatively, of Hadrosaurinae.
Non-hadrosaurid iguanodontians were the most diverse and abundant group of large-bodied herbivorous dinosaurs during the Early Cretaceous, and were a particularly important component of Laurasian ecosystems. Recent years have seen a dramatic increase in our knowledge of the diversity of this group, with multiple new taxa being described from northeast China. The most complete of these Chinese non-hadrosaurid iguanodontians is Jinzhousaurus yangi, from the middle part of the Yixian Formation (Lower Cretaceous: lower Aptian) of Liaoning Province. Here, we provide the first description of the relatively complete and partially articulated postcranial skeleton of the holotype of Jinzhousaurus, and provide detailed comparisons to closely related taxa. We document additional autapomorphies of Jinzhousaurus that provide strong support for the validity of this taxon.
New materials of Lesothosaurus diagnosticus permit a detailed understanding of one of the earliest and most primitive ornithischians. Skull proportions and suturai relations can be discerned from several articulated and disarticulated skulls. The snout is proportionately long with a vascularized, horn-covered tip. The premaxillary palate is broad and vomers are long and fused anteriorly. Unlike many later ornithischians, the postpalatine vacuities are broadly open. The basal tubera are short and gently depressed, and the epiotic contributes to the sidewall of the braincase. The mandibular symphysis is spout-shaped, and the dentition is marked by oblique wear facets, in contrast to earlier reports. The tooth-to-tooth wear facets and form of the predentary-dentary articulation suggest long-axis rotation of the mandibular rami during mastication.The forelimb is proportionately very short, with a partially opposable pollex. The ischium lacks an obturator process. The reduced hallux is held well above the substrate during locomotion.L. diagnosticus is diagnosed below on the basis of apomorphic features. Other “fabrosaurids” constitute a heterogeneous assemblage of poorly known ornithischians and hatchling prosauropods that do not share any apomorphic features with L. diagnosticus. Fabrosaurus australis is a nomen dubium, and, as a consequence, the family Fabrosauridae is invalid. Echinodon becklesii may represent a primitive heterodontosaur, and Tawasaurus, Fulengia, and portions of the holotype of Technosaurus represent hatchling prosauropods. Pisanosaurus mertii may be the most primitive ornithischian, as indicated by the form of the distal crus and astragalus, but a more precise phylogenetic assessment will require additional remains.
The genus Probactrosaurus was first established for material discovered by a joint Russian/Chinese expedition to the Chinese autonomous region of Neimongol (Inner Mongolia). Fossils were collected at a site named Maorty (= Maortu). Material attributable to ornithopod dinosaurs was considered sufficiently distinct to permit the definition of two species of the new genus: Probactrosaurus gobiensis and P. alashanicus. The former species was based on a considerable quantity of skeletal material, much of which is still to be found in the collections of the Palaeontological Institute (PIN), Moscow. The latter was based on far less well-preserved specimens, including a holotype (a posterior skull roof) that can no longer be found in the collections of the PIN and which, along with other materials, was reportedly returned to the Institute of Vertebrate Palaeontology and Palaeoanthropology, Beijing. Some remnants of the original material attributed to P. alashanicus have been located in the PIN collections. Both taxa, established by A. K. Rozhdestvensky, are re-described using all of the available material collected during the early Sino-Soviet expeditions. Probactrosaurus alashanicus is considered to be a junior subjective synonym of P. gobiensis. Further comparisons are made with the recently described species Probactrosaurus mazongshanensis Lu, 1997. The latter does not appear to be referable to the genus Probactrosaurus. Probactrosaurus is a gracile ornithopod (ranging between 4 and 6 m in length). The skull is unadorned by any form of cranial crest; however, the premaxillary beak is deflected ventrally and the dentition is similar to that seen in more derived hadrosaurid ornithopods. The postcranial skeleton is notable for its gracility, in particular the elongate forearm and manus, and the retention of a small, conical pollex spine. Systematic analysis suggests that P. gobiensis is a derived non-hadrosaurid iguanodontian ornithopod and the basal sister-taxon to the clade Hadrosauridae. The phylogeny of currently known iguanodontians is reviewed. © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 113–144.
Criteria for designating dinosaur genera are inconsistent, with very similar species highly split at the generic level and other, more disparate species combined into the same genus. A character census of Iguanodon bernissartensis and I. atherfieldensis shows that their postcrania are markedly more different than those of many other ornithopods, and that the gracile “Iguanodon” atherfieldensis is phylogentically more derived than the robust Iguanodon bernissartensis. Because of the considerable difference between the two taxa, a new genus is proposed for the gracile iguanodont Mantellisaurus atherfieldensis.
Vectisaurus valdensis is considered to be the imperfectly preserved remains of juvenile Iguanodon. Based on juvenile material of Iguanodon recovered from Nehden (Federal Republic of Germany), Vectisaurus is most probably referrable to I. atherfieldensis. Ornithopod relationships have been evaluated by reference to the detailed recent systematic reviews of the Ornithischia. Results from this study suggest that the family Iguanodontidae is valid, if more restricted than previously argued; that Tenontosaurus tilletti is more closely related to hypsilophodontians than iguanodontians; and, that Probactrosaurus gobiensis is the sister-taxon of the Hadrosauridae. A review cladogram of advanced ornithopod dinosaurs is proposed. -Author
The discovery in 1834 of a partial skeleton of Iguanodon in a quarry near Maidstone in Kent came at the perfect moment. During the 1820s and early 1830s numerous discoveries of the fragmentary remains of large fossil reptiles had been made in England. The block of Kentish Rag, upon which were preserved the scattered remains of the dinosaur Iguanodon (Mantell's "Mantel-piece') provided the early investigators of the anatomy and relationships of these reptiles with a partial, associated skeleton in which it is possible to identify many of the key osteological characteristics of one of the three founder members of the Dinosauria (Owen, 1942). In addition to some notes on the historical context into which the Maidstone speciment fell before, and after, its descovery, a belated description of the Maidstone Iguanodon is provided in this article and a reconstruction of this dinosaur has been attempted on the basis of these preserved remains. -from Author
This contribution reviews all the material that can be assigned to Barilium dawsoni (Lydekker). This includes the holotype, which is described in its entirety for the first time, and a number of referred specimens. The species is re-diagnosed on the basis of a number of unique characters and character combinations. Barilium is a robust (c. 10 m long) styracosternan iguanodontian ornithopod. Posterior dorsal and sacral vertebrae have tall, thick and inclined neural spines that were flanked by a lattice of ossified tendons and their centra bear thick keels. The ilium has a distinctive shape, and the sacrum (comprising one sacro-dorsal, five true sacrals and one sacrocaudal) is characterized by a prominent, discontinuous midline keel. Caudal vertebrae have 1-4 slope downward, away from the sacrum, and are subrectangular, posterior caudal centra are angular-sided and strongly amphicoelous. The forelimb has a very robust radius and ulna that are bound firmly together distally against a single, co-ossified carpal block. Pronation/supination of the forelimb was controlled by motion at a synovial joint between the proximal ends of the radius and ulna. Digit 1 of the manus is completely fused to the carpus, and the pollex ungual is uniquely short, blunt and laterally compressed and has a shallow vertical trough running down its lateral surface from apex to base. Barilium was probably an obligate quadruped and coexisted with an anatomically similar, but smaller and more lightly built, iguanodontian (Hyps-elospinus fittoni). Upper Jurassic and Lower Cretaceous iguanodontians are often represented by robust/large and gracile/small osteological (and taxonomic) pairs. A recent review has proposed two new taxonomic names for the material considered in this paper: a new generic name for the holotype and a new binomial for a referred specimen (NHMUK R3788). Both proposals are judged to be invalid: the new generic name suggested for the holotype is a junior objective synonym of Barilium dawsoni (Lydekker); the criteria proposed for the recognition of a new binomial for material herein to B. cf. dawsoni are suggested to be in error.
The unarmored, hadrosaurian dinosaurs of the late Cretaceous of North America constitute an interesting group about which much has been written and many species described. A review of this literature showed many different angles of approach, and it was in part to reconcile these various descriptions and reduce them to certain comparable common factors that this monographic study was undertaken. Aside from the mere compilation of the literature of these dinosaurs, redescriptions were prepared, nearly always in the presence of the original types and such other associated material as had come to light since the species was named.
The authors also undertook as complete a morphological study of the animals as the circumstances permitted, learning what they could of the mechanics of the skeleton and teeth, the musculature and integument, the nervous system and sense organs, and the probable functions of these various parts in the living animal. They further endeavored to imagine the reconstructed creatures in their appropriate environment—physical, climatic, vegetal, and animate—and to picture them and their manner of life as animate beings of a vanished age. An account of their distribution both in time and space is given, as well as a discussion of their probable phylogeny and the trend of their evolution.
This review summarizes current understanding of the history, anatomy, and taxonomy of British and Belgian iguanodontian dinosaurs. The earliest iguanodontian from this circumscribed region is Berriasian in age and represented by a well-preserved but crushed dentary with many teeth in situ; originally named Iguanodon hoggii Owen, 1874, this specimen has been studied and reassessed several times, and decisions concerning its taxonomic status and systematic position have proved to be consistently inconclusive. I. hoggii has recently been renamed Owenodon hoggii; however, the diagnostic anatomical characters that form the foundation for this new name are few and not taxonomically or systematically robust. It is considered appropriate to regard this undoubtedly important taxonomic entity as indicative of a basal (ankylopollexian) iguanodontian and to encourage new exploration for additional skeletal remains from Berriasian-aged deposits in England. Wealden iguanodontian taxonomy in England has also begun to be scrutinized more thoroughly. Difficulties encountered when trying to diagnose the original (Valanginian) type genus (Iguanodon Mantell, 1825) and species (Iguanodon anglicus Holl, 1829) created problems that were resolved using a rather unfortunate workaround that involved the use of a Barremian-Lower Aptian species: I. bernissartensis Boulenger in Van Beneden 1881. With regard to remains collected from numerous Wealden localities in southern England, it was recognized that known iguanodontians can be subdivided into anatomically and chronologically distinct groupings: an earlier (Valanginian) "fauna" represented by Barilium dawsoni (Lydekker, 1888) and Hypselospinus fittoni (Lydekker, 1889), and a later (Barremian-Lower Aptian) "fauna" comprising Iguanodon bernissartensis Boulenger in Van Beneden, 1881, and Mantellisaurus atherfieldensis (Hooley, 1925). The Belgian locality at Bernissart, assigned to the Sainte-Barbe Clays Formation (late Barremian-Lower Aptian) has yielded two taxa that have been recognized as anatomically similar to those identified in the contemporaneous Wealden deposits of southern England (the Weald Clay Group of the Wealden District and the Wealden Group of the Isle of Wight). Recent suggestions that further taxa can be diagnosed within the English and Belgian Wealden sequences are assessed (and rejected) on the basis of the evidence presented.
A theory is presented that cranial crests of hadrosaurs were visual and acoustical display organs. Facial morphology and phylogeny of the Hadrosauridae and earlier theories of crest function are reviewed. The following hypothesis is presented: cranial crests, whether hollow or solid, served as visual signal structures, and hollow lambeosaur crests were also vocal resonators; all crests promoted successful matings
within
species,
i.e.
, they served as premating genetic isolating mechanisms. The following predictions are tested and found to support the hypothesis: (1) hadrosaurs had well-developed eyes and ears; (2) external features of crests varied independently of internal structure; (3) crest variations were species-specific and sexually-dimorphic; (4) crest distinctiveness correlates with species diversity; (5) crest size tended to increase through time. The circumnarial depression on the side of the face in hadrosaurines housed an inflatable diverticulum of the nasal passage which served as a visual display organ. Primitive hadrosaurs (kritosaurs) possessed a small nasal horn used as a butting weapon in intraspecific combat. Because the weapon was also used in intimidative displays, narial diverticula evolved to draw attention to it. In the kritosaur
Brachylophosaurus
fighting was modified to ritualized head-pushing using the flat nasal “shield”. Saurolophines expanded the diverticula on to the elongated nasal horn, converting the weapon to a dominance rank symbol. In non-crested edmontosaurs, enlarged diverticula assumed a vocalization function. Lambeosaurs created resonators by enclosing the diverticula in bone; they further enhanced the resonator function of the nose by forming elongated “organ pipes” in the premaxillae. This “pushed” the olfactory region above the eyes as a conspicuous dome which then was modified to form species-specific visual display organs.
Hadrosauridae constitutes a very diverse clade of herbivorous dinosaurs that were extremely abundant during the Campanian–Maastrichtian (Late Cretaceous) of Europe, Asia, both Americas, and probably also Antarctica (Horner et al. 2004). The fact that hadrosaurids are one of the best-known clades of dinosaurs, represented by arguably the richest dinosaurian fossil record, contrasts with the scarcity of material and apparently undiagnostic nature of their type genus and species, Hadrosaurus foulkii. The holotype and only known specimen of H. foulkii is also historically significant for being the first skeletal remains of a dinosaur described outside Europe (Leidy 1858).
Approximately half of existing dinosaur species belonging to the Order Ornithischia, or the 'bird-hipped' dinosaurs, which include such familiar forms as the stegosaurs, ankylosaurs, hadrosaurs, and ceratopsids. Although ornithischians are generally conceded to have descended from a common ancestor, little is known about the pattern of descent. Comparison of more recently discovered ornithischian fossils from China and Mongolia to better-known North American forms has shed light on the pattern of evolutionary diversification among ornithischians, a pattern that began approximately 200 My ago and ended abruptly nearly 140 My later at the end of the Cretaceous.-from Author
A new species of the hadrosaurine hadrosaurid Gryposaurus was discovered in the late Campanian Kaiparowits Formation of southern Utah. Gryposaurus monumentensis, sp. nov. is distinguished from other Gryposaurus species by possessing a more robust skull, enlarged clover-shaped prongs on the predentary oral margin, an anteroposteriorly narrow infratemporal fenestra, and other autapomorphies plausibly associated with feeding adaptations. The derived morphology revealed in G. monumentensis necessitates revision of the generic diagnosis of Gryposaurus, including the addition of synapomorphies that further aid in distinguishing this taxon from Kritosaurus. A revised phylogenetic analysis places Gryposaurus within a monophyletic clade that includes Brachylophosaurus and Maiasaura. Gryposaurus monumentensis represents the most southern example of Gryposaurus, and underlines the remarkable diversification and long duration of this genus. Based on the phylogenetic, geographical, and stratigraphic evidence at hand, Gryposaurus was the most diverse genus within Hadrosaurinae; it also possessed one of the largest geographical and stratigraphic distributions, spanning more than five million years of the Campanian, and ranging from Alberta in the north to Utah (and possibly Texas) in the south. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 151, 351–376.
A bs t r ac t A computational model is used to estimate three-dimensional pelvic muscle moment arms for the saurolophine had-rosaur Edmontosaurus. The results are compared to models of the ornithischians Lesothosaurus and Kentrosaurus, the crocodilian Alligator, and the theropod Allosaurus in order to examine changes related to the evolution of quadruped-alism and to set the results in an evolutionary context. Ed-montosaurus and Kentrosaurus generally had higher flexion moment arms than the other taxa, suggesting a correlation with ornithischian quadrupedalism. Edmontosaurus had relatively high flexor and extensor moment arms compared to other dinosaurs, which could indicate increased locomotor performance in conjunction with decreased femoral excursion relating to a flexed hind limb stance. Alligator had the lowest flexion-extension and abduction moment arms and the highest adduction moment arms of all taxa modeled. Differences between Alligator and the dinosaurs probably reflect the different gaits utilized by these taxa. Dinosaurs use an upright gait emphasizing flexion and extension, while in the sprawling gait of Alligator, long-axis rotation and abduction -adduction joint excursions are also important. High adduction moments in Alligator can be attributed to the control of abductor moments generated around the hip by the ground reaction force acting on the horizontal femur; in contrast, adductor moments are generated around the hip in dinosaurs, and are controlled using abductor musculature.
Protohadros byrdi, gen. et sp. nov., from the Cenomanian Woodbine Formation, Texas, is described on the basis of a disarticulated skull and isolated postcrania. The possession of the fewest synapomorphies among hadrosaurids places Protohadros at the basal position within Hadrosauridae. The combination of a derived maxillopalatal unit and a primitive quadrate indicate a level of cranial kinesis intermediate between primitive iguanodontians and other hadrosaurids. Both the phylogenetic and chronological distributions of these characteristics describe an evolutionary sequence of adaptations in which modifications for increased masticatory ability of the maxillary region precede the evolution of both streptostylic cranial kinesis and a more derived mandible in Hadrosauridae. The taxon is unique among hadrosaurids in possessing a ventrally deflected muzzle, including a deep, rostrally massive mandible, that is interpreted to represent an exclusively low-browsing pattern of food acquisition in a deltaic environment. At 95 Ma, Protohadros is the oldest definitive hadrosaurid. This plus the phylogenetic and biogeographic position of the specimen indicate that a North American origin of Hadrosauridae is equally as likely as the prevalent Asian origin hypothesis.
Dollodon bampingi was recently named based upon a specimen from the Bernissart Quarry that had previously been referred to Mantellisaurus atherfieldensis. The initial diagnosis of Dollodon did not adequately distinguish it from Mantellisaurus or from other basal iguanodonts, necessitating a reassessment of the material. Firsthand examination of the holotypes of the two taxa and numerous other basal iguanodont specimens, as well as a principal components analysis of basal iguanodont dentaries, did not find any morphological features to justify the distinction of Dollodon from Mantellisaurus. D. bampingi is thus best considered a junior synonym of M. atherfieldensis. Furthermore, the recent referral of the species Iguanodon seelyi to the genus Dollodon is not supported; I. seelyi is indistinguishable from Iguanodon bernissartensis, and is considered a junior synonym of that species. Finally, the recently named taxon Proplanicoxa galtoni, also based upon a specimen formerly attributed to M. atherfieldensis, is considered a nomen dubium and probable junior synonym of M. atherfieldensis. Thus, only two species of large-bodied basal iguanodont should be recognized from the Barremian-Aptian of England and Belgium: M. atherfieldensis and I. bernissartensis.
Introductory.—The primary object of this communication is to bring to the notice of the Society numerous remains of an apparently new Iguanodont Reptile obtained by Mr. C. Dawson, F.G.S., of St. Leonards, from the Wadhurst Clay (one of the beds of the Hastings Sand, or lower division of the Wealden), and recently acquired by the British Museum; and also a maxilla from the Wealden of the Isle of Wight, apparently referable to Ornithopsis. Having, however, recently examined the whole of the collection of Dinosaurian remains preserved in the Museum, in the course of the preparation of the first part of the forthcoming ‘Catalogue of Fossil Reptilia’ of the collection, I have also made certain observations regarding other members of the order, which may be conveniently recorded at the same time.
Iguanodonts.—Commencing with the Iguanodonts, I may first of all observe that I fully concur in the view which M. Dollo informs me he now takes as to the specific identity of Iguanodon bernissartensis and I. Seelyi; and, although the original description is very meagre and unaccompanied by a figure, I think we ought to adopt the former and earlier name for the species which has been so well described by the Belgian naturalist. The British Museum possesses a considerable series of the remains of this species, many of which were referred by Sir R. Owen to Cetiosaurus and Pelorosaurus, while others have been described under the name of Iguanodon Mantelli.
In addition to the two Wealden species of Iguanodon (I.
On the 13th of October, 1871, I found, weathered out, lying on the cliff-foot, 300 yards east of the flagstaff near Brixton Chine, Isle of Wight, the fossil remains now submitted to the Society. The extreme autumnal heat had much cracked the surface of the clay in which the bones had been entombed; and these also were shattered into numberless small fragments, most of which could not be joined, so that parts of six vertebræ and of a large flat bone, which I regard as an ilium, were all that could be recovered. Since then I have several times revisited the spot in the hope of finding other portions of the skeleton, but fruitlessly; and as the cliff-foot is now wasted back to such a distance as to make the recovery of it most unlikely, the time has come when, without incurring the charge of undue haste, I may bring under the notice of the Society these evidences of what I venture to think will be received as a new Dinosaurian genus.
Completing our survey of British non-avian dinosaurs, we here review the ornithischians of Britain. Heterodontosaurids are present in the Lower Cretaceous Lulworth Formation of Dorset, and a few earlier possible records imply a long presence in the region of this clade. Britain's thyreophoran record is rich and includes the earliest well-represented taxon, Scelidosaurus, as well as Middle Jurassic stegosaurs and ankylosaurs including a reasonably good Cretaceous record of polacanthids and nodosaurids. Cretaceous stegosaurs are known only from fragmentary remains, but the proposal that stegosaurs were present as early as the Rhaetian is rejected. Among British iguanodontian omithopods, the possible dryosaurid Callovosaurits is the oldest global record whereas the proposed synonymy of Cumnoria with Camptosaurus requires confirmation. Iguanodon has become a taxonomic dumping ground for assorted iguanodontians and is in need of revision: most of the British species referred to this genus are almost certainly not closely allied to the neotype species 1. bernissartensis and require new generic names. Fragmentary remains suggest the early presence of hadrosaurids in Britain. The only British record of Marginocephalia, the Wessex Formation skull roof named Yaverlandia bitholus, appears not to belong to this clacle but seems to be from a maniraptoran theropod.
Three classifications of the Dinosauria have been proposed, which differ from each other in the principles on which their authors proposed to make the divisions. First in time is Professor Cope’s classification (‘Philadelphia, Acad. Nat. Sci. Proc.,’ November 13th, 1866, and December 31st, 1867; ‘Amer. Phil. Soc. Trans.,’ vol. 14, Part I). He relied upon the characters of the tarsus and the ilium; and on their varied condition divided Dinosaurs into three orders named Orthopoda, Goniopoda, and Symphopoda. In the Orthopoda , the generic types associated are Scelidosaurus, Hylæosaurus, Iguanodon, and Hadrosaurus. And in this group the relations of the tibia and fibula are compared to those of modern Lizards, the proximal tarsals being distinct from each other and from the tibia. The ilium has a narrowed anterior prolongation.
The bones of the fossil herbivorous reptile described in this paper were discovered in the sandstone of Tilgate Forest in Sussex, which is a portion of the iron-sand formation, and forms a chain of hills stretching in a W. N. W. direction from Hastings to Horsham. In this sandstone the bones and teeth in question are accompanied with those of saurian animals, turtles, birds, fishes, shells, and vegetables, among which may be satisfactorily traced the remains of a gigantic species of Crocodile, of the Megalosaurus, and of the Plesiosaurus. The teeth of the three last-mentioned animals are readily recognised and identified; but in the summer of 1822, others were discovered in the same strata, which, though evidently referrible to some herbivorous reptile, possessed peculiar and striking characters. Anxious to ascertain the opinions of naturalists respecting these, the author submitted them to the inspection of the most eminent, and among the rest to Baron Cuvier, who, while acknowledging that such teeth were previously unknown to him, agreed in the conclusion of their belonging to some herbivorous reptile of gigantic size, and recommended every research to be made for more connected portions of the skeleton.