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Resolving the evolutionary relationships of early diverging ('basal') ornithischian dinosaurs is a challenging topic in palaeontology, with multiple competing hypotheses on the phylogenetic relationships of heterodontosaurids, 'hypsilophodontids', and other early-diverging forms. These hypotheses cannot be directly compared because they are derived from differently constructed datasets (i.e. distinct samples of taxa and characters). This study aims to address these issues by revising and combining the distinct datasets into a single analysis in order to create the most comprehensive dataset for the investigation of the phylogenetic relationships of early-diverging ornithischians. A diphyletic model of Dinosauria is supported, with silesaurs nesting as members of Ornithischia. Heterodontosauridae is resolved as a clade of non-genasaurian ornithischians, rejecting a potential relationship with Marginocephalia. 'Hypsilophodontid' taxa span the neornithischian and ornithopod stem, with Thescelosauridae as the sister taxon to Cerapoda. A more restricted Ornithopoda is composed of five main clades: Hypsilophodontidae, Rhabdodontomorpha, Elasmaria, Dryosauridae and Ankylopollexia. Hypsilophodontidae is a valid clade, reduced to two European Barremian taxa. Rhabdodontomorpha does not contain Muttaburrasaurus as originally proposed, but instead expands to include a North American clade formed by Convolosaurus, Iani and Tenontosaurus. Elasmaria contains all non-dryomorph Gondwanan ornithopods, with its members possessing multiple distinct body plans. New results and comparison with previous studies suggest that some members of Dryosauridae are not 'true dryosaurids' but various early euiguanodontians that may be more closely related to either Elasmaria or Ankylopollexia. Results group most 'hypsilophodontids' in larger clades, significantly reducing the number and extension of ghost lineages throughout all of Neornithischia. These clades also show a degree of endemism, with different lineages present at different continents in the Late Cretaceous. This new phylogenetic analysis unifying previous works will provide a framework for future studies on origins and relations of early diverging ornithischians, and attempting to find stability among the different competing hypotheses. [ABSTRACT FROM AUTHOR]

Derived ornithopods, such as hadrosaurids, show a high occurrence of fossilized lesions and diseases. However, paleopathologies in iguanodontians seem to be less common, considering the rich fossil record of these taxa in Europe, in particular in Belgium, Britain and Spain. Here, we describe an iguanodontian femur discovered in England that exhibits a large overgrowth of its lateral aspect, not previously recognized in any other similar remains. The specimen was scanned with micro‐computed tomography (microCT) and later sectioned in three sites of the overgrowth for histological analysis. The femur belongs to an early adult Iguanodontia indet., based on the presence of a woven parallel fibered complex in the outer cortex and three to four lines of arrested growth. Internal analysis of the dome‐like overgrowth suggests it can be diagnosed as a fracture callus. The injury might have negatively impacted upon the animal's locomotion as the trauma had occurred in the region above the knee, a crucial spot for hindlimb musculature. Finally, a cancellous medullary bone‐like tissue was recognized in the medullary cavity next to the pathological overgrowth. An attempt was made to determine the precise nature of this tissue, as medullary bone is linked with the ovulation period in (avian) dinosaurs, whereas other types of endosteal, medullary bone‐like tissue have previously been recognized in pathological bones. [ABSTRACT FROM AUTHOR]

Abstract Background Tooth replacement patterns of early-diverging ornithischians, which are important for understanding the evolution of the highly specialized dental systems in hadrosaurid and ceratopsid dinosaurs, are poorly known. The early-diverging neornithischian Jeholosaurus, a small, bipedal herbivorous dinosaur from the Early Cretaceous Jehol Biota, is an important taxon for understanding ornithischian dental evolution, but its dental morphology was only briefly described previously and its tooth replacement is poorly known. Results CT scanning of six specimens representing different ontogenetic stages of Jeholosaurus reveals significant new information regarding the dental system of Jeholosaurus, including one or two replacement teeth in nearly all alveoli, relatively complete tooth resorption, and an increase in the numbers of alveoli and replacement teeth during ontogeny. Reconstructions of Zahnreihen indicate that the replacement pattern of the maxillary dentition is similar to that of the dentary dentition but with a cyclical difference. The maxillary tooth replacement rate in Jeholosaurus is probably 46 days, which is faster than that of most other early-diverging ornithischians. During the ontogeny of Jeholosaurus, the premaxillary tooth replacement rate slows from 25 days to 33 days with similar daily dentine formation. Conclusions The tooth replacement rate exhibits a decreasing trend with ontogeny, as in Alligator. In a phylogenetic context, fast tooth replacement and multi-generation replacement teeth have evolved at least twice independently in Ornithopoda, and our analyses suggest that the early-diverging members of the major ornithischian clades exhibit different tooth replacement patterns as an adaption to herbivory.

The Maestrat Basin, in the Iberian Range, has proved to be a key point for the study of the hadrosauriform dinosaurs of the Lower Cretaceous in Europe. The Aliaga, Galve, and Morella sub-basins have all yielded abundant fossils of Mesozoic vertebrates, among which dinosaurs, and especially hadrosauriform styracosternan ornithopods, are the most abundant group from these areas. In this article, we review recent findings in the Maestrat Basin, which suggest that the diversity of this clade during the Barremian-Albian interval was greater than originally thought, providing us with valuable information for the study and understanding of the evolution of these dinosaurs. [ABSTRACT FROM AUTHOR]

La cuenca del Maestrat, en la cordillera ibérica, se ha revelado como un punto clave para el estudio de los dinosaurios hadrosauriformes del Cretácico Inferior de Europa. Las subcuencas de Aliaga, Galve y Morella han aportado abundantes fósiles de vertebrados mesozoicos, entre los cuales los dinosaurios, y en concreto los ornitópodos estiracosternos hadrosauriformes, son el grupo más abundante en estas zonas. En el presente artículo, revisamos los hallazgos recientes en la cuenca del Maestrat, que sugieren que la diversidad de este clado durante el Barremiense-Albiense era más amplia de lo que se pensaba inicialmente, lo que nos ofrece una información muy valiosa para estudiar y entender la evolución de estos dinosaurios.

The Horseshoe Canyon Formation has provided a wealth of vertebrate skeletal fossils over the past 100 years of collection. Vertebrate trace fossils such as footprints and trackways, however, have been markedly underrepresented. Trackways can provide a wealth of information regarding behaviour and soft tissues reflective of autopodial anatomy. Discovery of several giant, high-fidelity ichnites in series from the Morrin Member represents the first definitive dinosaur trackway reported from the Horseshoe Canyon Formation. The trackway is composed of three footprint casts in series, alongside 22 associated ichnites. The ichnites were formed in soft sediment molds along a non-uniform walking surface. The deep substrates allowed for the preservation of both the plantar surface and dorsal components of the trackmakers' feet. Some ichnites show soft tissue morphologies like interdigital webbing, toe pads, and skin impressions. Presence of these features and small kidney-shaped forelimb prints allow referral to Hadrosauropodus langstoni. The preservation of the trackway demonstrates asymmetries useful for comparison of the relief and impression surfaces of prints using both discrete and morphometric characteristics, improving confidence in identifying partial or isolated Hadrosauropodus prints of various modes of formation. [ABSTRACT FROM AUTHOR]

The Upper Jurassic Lourinhã Formation is well known for its rich assemblage of fossil vertebrates. In this formation, ornithopod dinosaurs are represented by two iguanodontian species, Eousdryosaurus nanohallucis and Draconyx loureiroi. We recently became aware of unreported material belonging to the holotype of Draconyx loureiroi , consisting of partially articulated manual elements. We here re-describe the holotype specimen ML 357, including the newly discovered material. The specimen was subjected to CT-scanning and its surface data used to assess anatomical characters. Linear measurements of metatarsal III were used to estimate the body length of the specimen. The Draconyx loureiroi holotype was included in two datasets and analysed with maximum parsimony and Bayesian inference approaches to estimate evolutionary rates among Iguanodontia. We present evidence that Draconyx loureiroi is a valid taxon nested in Styracosterna and is clearly diagnosable by a unique combination of characters. Both maximum parsimony and Bayesian inference indicate high evolutionary rates across the Jurassic/Cretaceous transition for the base of Iguanodontia. Length estimation suggests that Draconyx loureiroi was a relatively small, bipedal and possibly cursorial animal. Given its basal phyletic position, we interpret this bauplan was the ancestral condition for Styracosterna, that only later in the Cretaceous evolved into giant quadrupedal forms. [ABSTRACT FROM AUTHOR]

This work attempts at providing a revised framework for ornithischian phylogeny, based on an exhaustive data compilation of already published analyses, a critical re-evaluation of osteological characters and an in-depth checking of characters scoring to fix mistakes that have accumulated in previous analyses; we have also included recently described basal ornithischians, marginocephalians and ornithopods. 'Heterodontosaurids' are recovered as a paraphyletic group of basal Marginocephalia that progressively lead to the dome-headed 'true' pachycephalosaurs. 'Heterodontosaurids' consequently fall within Pachycephalosauria sensu Sereno, 1998. The reconfiguration of basal cerapodan relationships pulls the origins of ornithopods to the earliest stages of the Jurassic. Based on the present analysis, we also discuss ornithopod relationships, with a particular focus on basal Iguanodontia. Tenontosaurus is found as the basalmost iguanodontian. The monophyly of Rhabdodontomorpha in a position more derived than Tenontosaurus is supported by the present analysis. [ABSTRACT FROM AUTHOR]

The aim of the present contribution is to describe the first ornithischian species from the Huincul Formation (Cenomanian-Turonian, Upper Cretaceous) at the Pueblo Blanco Natural Reserve, Río Negro province, Argentina. The new species, named Chakisaurus nekul gen. et sp. nov., can be comfortably included among elasmarian ornithopods. The new species shows humeral anatomy that is congruent with smaller members of the clade (e.g. Anabisetia, Notohypsilophodon), and differs from larger taxa (e.g. Talenkauen, Mahuidacursor) which show humeral features probably related with graviportal habits, such as lack of shaft torsion and a distally located deltopectoral crest. This indicates that graviportal habits were probably acquired independently in elasmarians from other large-sized taxa, such as hadrosauroids. Caudal vertebrae of the new species also show a unique combination of characters shared with other elasmarians, which are absent in previously known ornithopods. These features indicate that some elasmarians had a protonic tail posture, which is unknown in other ornithischians and was previously considered unique to derived titanosaurian sauropods. The shape of transverse processes and neural spines of caudal vertebrae indicate that at least some elasmarians had improved cursorial habilities, that were convergently acquired by selected theropod clades. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous ‘upper’ Winton Formation of Queensland, Australia is world famous for hosting Dinosaur Stampede National Monument at Lark Quarry Conservation Park, a somewhat controversial tracksite that preserves thousands of tridactyl dinosaur tracks attributed to ornithopods and theropods. Herein, we describe the Snake Creek Tracksite, a new vertebrate ichnoassemblage from the ‘upper’ Winton Formation, originally situated on Karoola Station but now relocated to the Australian Age of Dinosaurs Museum of Natural History. This site preserves the first sauropod tracks reported from eastern Australia, a small number of theropod and ornithopod tracks, the first fossilised crocodyliform and ?turtle tracks reported from Australia, and possible lungfish and actinopterygian feeding traces. The sauropod trackways are wide-gauge, with manus tracks bearing an ungual impression on digit I, and anteriorly tapered pes tracks with straight or concave forward posterior margins. These tracks support the hypothesis that at least one sauropod taxon from the ‘upper’ Winton Formation retained a pollex claw (previously hypothesised for Diamantinasaurus matildae based on body fossils). Many of the crocodyliform trackways indicate underwater walking. The Snake Creek Tracksite reconciles the sauropod-, crocodyliform-, turtle-, and lungfish-dominated body fossil record of the ‘upper’ Winton Formation with its heretofore ornithopod- and theropod-dominated ichnofossil record.

Post-Wealden dinosaur remains are rare in the UK, so any material from late Early or Late Cretaceous deposits is potentially of palaeoecological and palaeobiogeographical significance. Four dinosaur specimens collected from the Woburn Sands Formation (Aptian) of Upware, Cambridgeshire were described briefly by Walter Keeping in 1883, but have not been reappraised since. These specimens are identified herein as a ?turiasaurian sauropod tooth and indeterminate iguanodontian ornithopod remains (a tooth, middle caudal vertebra, pollex ungual). Although collected from the Woburn Sands Formation, it is likely that all of these fossils were reworked from older (now absent) sediments and they have usually been regarded as either 'Wealden' or Neocomian in age, presumably due to previous identifications of some of these specimens as Iguanodon. However, consideration of UK dinosaur faunas and regional geology indicates that these fossils could potentially be older. Further work is needed on the derived terrestrial fossils of the Lower Greensand Group in order to constrain their ages more precisely so that they can be incorporated into broader studies of regional diversity and palaeoecology. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous 'upper' Winton Formation of Queensland, Australia is world famous for hosting Dinosaur Stampede National Monument at Lark Quarry Conservation Park, a somewhat controversial tracksite that preserves thousands of tridactyl dinosaur tracks attributed to ornithopods and theropods. Herein, we describe the Snake Creek Tracksite, a new vertebrate ichnoassemblage from the 'upper' Winton Formation, originally situated on Karoola Station but now relocated to the Australian Age of Dinosaurs Museum of Natural History. This site preserves the first sauropod tracks reported from eastern Australia, a small number of theropod and ornithopod tracks, the first fossilised crocodyliform and ?turtle tracks reported from Australia, and possible lungfish and actinopterygian feeding traces. The sauropod trackways are wide-gauge, with manus tracks bearing an ungual impression on digit I, and anteriorly tapered pes tracks with straight or concave forward posterior margins. These tracks support the hypothesis that at least one sauropod taxon from the 'upper' Winton Formation retained a pollex claw (previously hypothesised for Diamantinasaurus matildae based on body fossils). Many of the crocodyliform trackways indicate underwater walking. The Snake Creek Tracksite reconciles the sauropod-, crocodyliform-, turtle-, and lungfish-dominated body fossil record of the 'upper' Winton Formation with its heretofore ornithopodand theropod-dominated ichnofossil record. [ABSTRACT FROM AUTHOR]

Paleopathology, or the study of ancient injuries and diseases, can enable the ecology and life history of extinct taxa to be deciphered. Large‐bodied ornithopods are the dinosaurs with the highest frequencies of paleopathology reported to‐date. Among these, the crested hadrosaurid Parasaurolophus walkeri is one of the most famous, largely due to its dramatic elongated and tubular nasal crest. The holotype of Parasaurolophus walkeri at the Royal Ontario Museum, Canada, displays several paleopathologies that have not been discussed in detail previously: a dental lesion in the left maxilla, perhaps related to periodontal disease; callus formation associated with fractures in three dorsal ribs; a discoidal overgrowth above dorsal neural spines six and seven; a cranially oriented spine in dorsal seven, that merges distally with spine six; a V‐shaped gap between dorsal spines seven and eight; and a ventral projection of the pubic process of the ilium which covers, and is fused with, the lateral side of the iliac process of the pubis. These lesions suggest that the animal suffered from one or more traumatic events, with the main one causing a suite of injuries to the anterior aspect of the thorax. The presence of several lesions in a single individual is a rare observation and, in comparison with a substantial database of hadrosaur paleopathological lesions, has the potential to reveal new information about the biology and behavior of these ornithopods. The precise etiology of the iliac abnormality is still unclear, although it is thought to have been an indirect consequence of the anterior trauma. The discoidal overgrowth above the two neural spines also seems to be secondary to the severe trauma inflicted on the ribs and dorsal spines, and probably represents post‐traumatic ossification of the base of the nuchal ligament. The existence of this structure has previously been considered in hadrosaurs and dinosaurs more generally through comparison of origin and insertion sites in modern diapsids (Rhea americana, Alligator mississippiensis, Iguana iguana), but its presence, structure, and origin‐attachment sites are still debated. The V‐shaped gap is hypothesized as representing the point between the stresses of the nuchal ligament, pulling the anterior neural spines forward, and the ossified tendons pulling the posterior neural spines backward. Different reconstructions of the morphology of the structure based on the pathological conditions affecting the neural spines of ROM 768 are proposed. Finally, we review the history of reconstructions for Parasaurolophus walkeri showing how erroneous misconceptions have been perpetuated over time or have led to the development of new hypotheses, including the wide neck model supported in the current research. [ABSTRACT FROM AUTHOR]

A new basal ornithopod dinosaur, based on two nearly complete articulated skeletons, is reported from the Lujiatun Beds (Yixian Fm, Lower Cretaceous) of western Liaoning Province (China). Some of the diagnostic features of Changmiania liaoningensis nov. gen., nov. sp. are tentatively interpreted as adaptations to a fossorial behavior, including: fused premaxillae; nasal laterally expanded, overhanging the maxilla; shortened neck formed by only six cervical vertebrae; neural spines of the sacral vertebrae completely fused together, forming a craniocaudally-elongated continuous bar; fused scapulocoracoid with prominent scapular spine; and paired ilia symmetrically inclined dorsomedially, partially covering the sacrum in dorsal view. A phylogenetic analysis places Changmiania liaoningensis as the most basal ornithopod dinosaur described so far. It is tentatively hypothesized that both Changmiania liaoningensis specimens were suddenly entrapped in a collapsed underground burrow while they were resting, which would explain their perfect lifelike postures and the complete absence of weathering and scavenging traces. However, further behavioural inference remains problematic, because those specimens lack extensive sedimentological and taphonomic data, as it is also the case for most specimens collected in the Lujiatun Beds so far.

Dinosaurs were remarkably climate-tolerant, thriving from equatorial to polar latitudes. High-paleolatitude eggshells and hatchling material from the Northern Hemisphere confirms that hadrosaurid ornithopods reproduced in polar regions. Similar examples are lacking from Gondwanan landmasses. Here we describe two non-iguanodontian ornithopod femora from the Griman Creek Formation (Cenomanian) in New South Wales, Australia. These incomplete proximal femora represent the first perinatal ornithopods described from Australia, supplementing neonatal and slightly older 'yearling' specimens from the Aptian–Albian Eumeralla and Wonthaggi formations in Victoria. While pseudomorphic preservation obviates histological examination, anatomical and size comparisons with Victorian specimens, which underwent previous histological work, support perinatal interpretations for the Griman Creek Formation femora. Estimated femoral lengths (37 mm and 45 mm) and body masses (113–191 g and 140–236 g), together with the limited development of features in the smallest femur, suggest a possible embryonic state. Low body masses (<1 kg for 'yearlings' and ~20 kg at maturity) would have precluded small ornithopods from long-distance migration, even as adults, in the Griman Creek, Eumeralla, and Wonthaggi formations. Consequently, these specimens support high-latitudinal breeding in a non-iguanodontian ornithopod in eastern Gondwana during the early Late Cretaceous. [ABSTRACT FROM AUTHOR]

Talenkauen santacrucensis represents one of the most complete South American ornithopods yet discovered. This dinosaur comes from the Mata Amarilla Formation (Turonian) of Santa Cruz Province, Argentina. The aim of this contribution is to present a detailed description of Talenkauen santacrucensis. Features of the cervical series of Talenkauen, which are shared with other elasmarians, indicate that these dinosaurs have a proportionally longer neck than other ornithopods. These traits were convergently acquired by several saurischian clades. Additionally, some features, including an ornamented labial surface of the mandibular teeth and a sigmoidal greater trochanter of femur, are traits shared by most elasmarians, and may prove to be synapomorphies of this clade. A phylogenetic analysis recovers most Cretaceous Gondwanan ornithopods in the clade Elasmaria. This analysis indicates that Elasmaria was distributed more widely geographically and temporally than previously thought. [ABSTRACT FROM AUTHOR]

Abstract The fossiliferous site of La Cantalera-1 (Teruel, Spain) has to date provided remains of more than 30 vertebrate taxa, including dinosaurs, crocodyliforms, pterosaurs, mammals, lizards, turtles, lissamphibians and teleosteans. Located in the lower part of the Blesa Formation (lower Barremian), it is one of the richest vertebrate-bearing deposits from the Lower Cretaceous of the Iberian Peninsula. In this work, taphonomic and palaeohistological studies are carried out on the basis of ornithischian (Ornithopoda and Ankylosauria) dinosaur samples in order to assess the diagenetic processes, to characterize the histological microstructures and, if possible, to make palaeobiological inferences about the state of maturation of the individuals. A variety of techniques are used in the taphonomic study, including scanning electron microscopy (SEM), cathodoluminescence (CL), X-ray diffraction (XRD) and ultraviolet fluorescence (UVF). The bone of the dinosaur samples has been converted into francolite (fluorapatite carbonate); the trabecular cavities are filled with semi-spherical forms of goethite and two different phases of calcite. In addition, the SEM and UVF techniques suggest the activity of coccoid-form bacteria and filaments of bacterial origin (biofilms?) in the bones, which possibly favoured fossilization. The dinosaur remains were subjected to fossil-diagenetic processes in a phreatic environment after a rapid burial, without appreciable seasonality effects. On the other hand, the palaeohistological study of both skeletal and dermal bones found in La Cantalera-1 shows a community of herbivorous dinosaurs composed mostly of immature ornithopods and at least one Polacanthus -like ankylosaur, as suggested by the organizational pattern of structural collagen fibres seen in some samples. The palaeobiological inferences drawn from this study support previous interpretations of a relative abundance of immature ornithischians in La Cantalera-1. Highlights • First palaeohistological study of Ornithischia from La Cantalera-1 (Spain). • Presence of Polacanthus -like ankylosaur suggested by histological features of osteoderms. • Mineral fill suggests the dinosaur bones underwent rapid burial in a phreatic environment. • Evidence of microbial (nanobacterial) participation, possibly favouring fossilization. [ABSTRACT FROM AUTHOR]

Abstract A new ornithopod dinosaur, the medium-sized Sektensaurus sanjuanboscoi gen. et sp nov. from the Coniacian–Maastricthian strata of the Lago Colhué Huapi Formation, Golfo San Jorge Basin, Patagonia, is here described. The specimen consists of disarticulated postcranial bones belonging to a single individual. It is diagnosed by an unique association of five autapomorphies on the dorsal and sacral vertebrae and the humerus. A cladistics analysis indicates that Sektensaurus was an iguanodontian ornithopod which inhabited Patagonia during the Late Cretaceous. Likewise, Sektensaurus is the first non-hadrosaurid, probably elasmarian, ornithopod recorded from the uppermost Cretaceous of central Patagonia. In a broad context, this discovery increases the anatomical knowledge of ornithopods and adds new data on the composition of dinosaur faunas that lived in Patagonia close to the Antarctica, at the end of the Cretaceous. [ABSTRACT FROM AUTHOR]

The Lower Cretaceous Wessex Formation of the Isle of Wight, UK, has produced a diverse dinosaurian fauna over the past 150 years. Hypsilophodontids are the most common small dinosaurs in the assemblage. Currently all hypsilophodontids are referred to Hypsilophodon foxii , originally described based on skulls and skeletons from the Hypsilophodon bed near Cowleaze Chine, in the uppermost Wessex Formation. We report a new hypsilophodontid, Vectidromeus insularis gen. et sp. nov., from exposures near Sudmoor Point, lying at the base of the exposed Wessex, ∼150 m below the Hypsilophodon beds. Associated elements of the dorsal vertebrae, pelvis, hindlimbs, and tail are preserved. The specimen represents a juvenile, but differs from adult and juvenile Hypsilophodon foxii in the short and deep posterior iliac blade, short pubic peduncle, laterally exposed brevis fossa, rectangular ischia, and large fourth trochanter. Vectidromeus adds to the diversity of dinosaurs in the Wessex Formation. With other putative hypsilophodontids now assigned to other families, the Hypsilophodontidae currently comprises just Hypsilophodon and Vectidromeus , both from the Wessex Formation of the Isle of Wight. Hypsilophodontidae appear to be endemic to the Early Cretaceous of Europe. [ABSTRACT FROM AUTHOR]

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.

Abstract: Three species of ornithischian dinosaurs (Daurosaurus olovus, Kulindapteryx ukureica, and Kulindadromeus zabaikalicus) from the Jurassic Kulinda locality (Transbaikalia, Russia) have been described. Kulindadromeus zabaikalicus was established on erroneous assumption that the locality contains only one dinosaurian taxon. The characters used in the diagnosis of this species, which were registered by the holotype (imprint of bones of an incomplete distorted skull on the rock surface), cannot be treated unequivocally from the morphological point of view. [ABSTRACT FROM AUTHOR]

Ceratopsia includes some of the best-known ornithischian dinosaurs. Many species are erected based on cranial elements alone, and the postcranial skeletons are either missing or undescribed in many taxa. Here we provide the first detailed postcranial description of Yinlong downsi based on the holotype and eight other well-preserved skeletons. Yinlong downsi from the early Late Jurassic Shishugou Formation of the Wucaiwan area, Xinjiang, China, represents one of the most basal ceratopsians. The detailed study of the postcranial skeleton reveals one feature unique to it among ceratopsians: a blade-like prepubic process of the pubis with an elongate notch near its ventral margin. The postcranial material of Yinlong shares some unique features with that of the ornithischian Stenopelix valdensis from the Early Cretaceous of Germany, and provides further evidence that the latter is a basal ceratopsian. A comprehensive phylogenetic analysis of basal ornithischians was built based on 72 taxa and 380 characters. Most of the characters are illustrated for the first time in order to clarify character states. The new ornithischian phylogeny confirms that Yinlong belongs to Chaoyangsauridae. Chaoyangsaurids and Psittacosaurus form a monophyletic group that is sister to all other ceratopsians. The new phylogeny also supports Stenopelix valdensis as a basal ceratopsian, and Mosaiceratops to be close to Coronosauria. Additionally, the new phylogeny agrees with other recent analyses that place heterodontosaurids as the most basal ornithischians rather than with marginocephalians. Furthermore, Isaberrysaura, which has been hypothesized to be a basal ornithopod, is recovered as one of the most basal stegosaurs for the first time. The former ‘hypsilophodontid’ taxa are recovered within Ornithopoda rather than outside Cerapoda, and Jeholosauridae is shown to be valid in this analysis. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The great diversity of dinosaurian tooth shapes and sizes, and in particular, the amazing dental complexity in derived ornithischians has attracted a lot of attention. However, the evolution of dental batteries in hadrosaurids and ceratopsids is difficult to understand without a broader comparative framework. Here we describe tooth histology and development in the "middle" Cretaceous ornithischian dinosaur Changchunsaurus parvus, a small herbivore that has been characterized as an early ornithopod, or even as a more basal ornithischian. We use this taxon to show how a "typical" ornithischian dentition develops, copes with wear, and undergoes tooth replacement. Although in most respects the histological properties of their teeth are similar to those of other dinosaurs, we show that, as in other more derived ornithischians, in C. parvus the pulp chamber is not invaded fully by the newly developing replacement tooth until eruption is nearly complete. This allowed C. parvus to maintain an uninterrupted shearing surface along a single tooth row, while undergoing continuous tooth replacement. Our histological sections also show that the replacement foramina on the lingual surfaces of the jaws are likely the entry points for an externally placed dental lamina, a feature found in many other ornithischian dinosaurs. Surprisingly, our histological analysis also revealed the presence of wavy enamel, the phylogenetically earliest occurrence of this type of tissue. This contradicts previous interpretations that this peculiar type of enamel arose in association with more complex hadrosauroid dentitions. In view of its early appearance, we suggest that wavy enamel may have evolved in association with a shearing-type dentition in a roughly symmetrically-enameled crown, although its precise function still remains somewhat of a mystery. [ABSTRACT FROM AUTHOR]

The Cretaceous landmass of Appalachia has preserved an understudied but nevertheless important record of dinosaurs that has recently come under some attention. In the past few years, the vertebrate faunas of several Appalachian sites have been described. One such locality, the Ellisdale site of the Cretaceous Marshalltown Formation of New Jersey, has produced hundreds of remains assignable to dinosaurs, including those of hadrosauroids of several size classes, indeterminate ornithopods, indeterminate theropods, the teeth, cranial, and appendicular elements of dromaeosaurids, ornithomimosaurians, and tyrannosauroids, and an extensive microvertebrate assemblage. The theropod dinosaur record of the Ellisdale site is currently the most extensive and diverse known from the Campanian of Appalachia. Study of the Ellisdale theropod specimens suggests that at least four or more non-avian theropod taxa are represented at the site, including tyrannosauroids, ornithomimosaurs, several different morphotypes of dromaeosaurids that are the first of that clade described from New Jersey, and indeterminate theropods. The specimens are important for increasing current knowledge about the theropod diversity of the Atlantic Coastal Plain (ACP) during the Campanian by representing the most speciose assemblage of the group during the time in the ACP as well as for shedding light on Appalachian dinosaur ecology and biogeography generally. [ABSTRACT FROM AUTHOR]

During their long evolutionary history, neornithischian dinosaurs diverged into several clades with distinctive adaptations. However, the early evolution within Neornithischia and the resolution of the phylogenetic relationships of taxa situated near the base of the clade remain problematic. This is especially true for those taxa traditionally placed at the base of Ornithopoda, either as ‘hypsilophodontids’ or at the base of the diverse clade Iguanodontia. Recent studies are improving our understanding of the anatomy and relationships of these taxa, with discoveries of several new non-ankylopollexian ornithopods from South America and Europe providing key insights into early ornithopod evolution and palaeobiogeography. Here, we describe a new basal ornithopod, Burianosaurus augustai gen. et sp. nov., based on a well-preserved femur from the upper Cenomanian strata (Korycany Beds of the Peruc-Korycany Formation) of the Czech Republic. The new taxon is diagnosed by a unique suite of characters and represents the only occurrence of a Cenomanian non-avian dinosaur in Central Europe north of the Alpine Tethyan areas. Histological examination of the type specimen reveals the presence of a loosely packed Haversian system which suggests relatively mature bone from a possible young adult. Phylogenetic analyses of two different data sets, selected to test the placement of B. augustai in various parts of the neornithischian tree, reconstruct B. augustai as a basal ornithopod, firmly nested outside Ankylopollexia. These results also support a diverse Elasmaria as a basal clade within Ornithopoda and reconstruct Hypsilophodon outside Ornithopoda as the sister taxon to Cerapoda. However, the relationships of ‘hypsilophodontids’ within Neornithischia remain contentious. http://zoobank.org/urn:lsid:zoobank.org:pub:D28A9FB8-A253-4032-8710-4F51668A1E4F [ABSTRACT FROM AUTHOR]

The lower Maastrichtian site of Basturs Poble (southern Pyrenees, Spain) is the first hadrosaur bonebed reported from Europe. It is an accumulation of disarticulated lambeosaurine skeletal elements, possibly belonging to Pararhabdodon isonensis. The sample shows high intraspecific morphological variability among many skeletal elements, suggesting the need for caution in choosing characters for phylogenetic analyses. Juvenile to adult individuals are represented in the sample, while hatchling remains are absent. Bone histology reveals that juveniles are over-represented and that the youngest individuals represented by tibia specimens were two years old. Adult individuals, with tibiae 550–600 mm long, were 14–15 years old when they died. However, individual variation in tibia length at skeletal maturity occurs within the sample, so individual maturity cannot be assumed on the basis of bone size alone. The Basturs Poble bonebed occurs within the upper part of the C31r magnetochron. Thus, lambeosaurine hadrosaurids were already present and abundant in the Ibero-Armorica Island at the end of the early Maastrichtian and P. isonensis spans the upper part of the lower Maastrichtian to the upper part of the upper Maastrichtian (upper part of C31r-lower part of C29r). [ABSTRACT FROM AUTHOR]

Two new dinosaur tracksites are reported from the Lower Cretaceous Jiaguan Formation in the Sichuan Basin, Qijiang District of Chongqing. These are the Gaoqing-Yongsheng and the Huibu tracksites, which represent the 13th and 14th reports from this formation. The Gaoqing-Yongsheng tracksite reveals the trackway of a large biped (ornithopod) in association with isolated sauropod tracks and large indeterminate undertracks with radial cracks. These features are preserved as natural casts with pebble infillings in a coarse, cross bedded and very thick bedded sandstone sequence. The Huibu tracksite reveals isolated theropod tracks and ornithopod tracks, the latter having a quadripartite, Caririchnium-like morphology, preserved in a thin bedded sandstone sequence with intercalated mudstone. [ABSTRACT FROM AUTHOR]

Despite the Hebrides and Cleveland basins being geographically close, research has not previously been carried out to determine faunal similarities and assess the possibility of links between the dinosaur populations. The palaeogeography of both areas during the Middle Jurassic shows that there were no elevated landmasses being eroded to produce conglomeratic material in the basins at that time. The low-lying landscape and connected shorelines may have provided connectivity between the two dinosaur populations. The dinosaur fauna of the Hebrides and Cleveland basins has been assessed based primarily on the abundant ichnites found in both areas as well as their skeletal remains. In the two basins, the dinosaur faunas are very similar, consisting of non-neosauropod eusauropods, a possible basal titanosauriform, large and small theropods and ornithopods and europodan thyreophorans. The main difference in the faunas is in the sizes. In the Cleveland Basin, the ichnites suggest that there were medium and large theropods alongside small to medium sized ornithopods, whereas, in the Hebrides Basin, the theropods were from small to large and the ornithopods were medium to large. It is suggested that migrations could have taken place between the two areas during the Middle Jurassic. A tentative food chain from the herbivorous dinosaurs to the top predators can be inferred from the footprints. [ABSTRACT FROM AUTHOR]

Nipponosaurus sachalinensis is the only definitive lambeosaurine hadrosaurid from Sakhalin Island of Russia. Previous studies suggested it was a member of Lambeosaurini (derived lambeosaurines). However, its phylogenetic status within Lambeosaurini remains controversial. In addition, some studies argued the juvenile ontogenetic stage of the holotype and regarded Nipponosaurus as an invalid taxon. In order to solve these problems, its definite growth stage is determined through histological studies. Absence of a line of arrested growth, presence of osteons with large vascular spaces, and presence of primary bone remnants even in the highly modified regions of the femur confirm that the holotype was a juvenile. More than a hundred of the 350 characters used to determine the phylogenetic position of Nipponosaurus are ontogenetically variable characters based on the different ontogenetic stages of Hypacrosaurus stebingeri. Our phylogenetic analysis reveals that Nipponosaurus is a basal lambeosaurine hadrosaurid, much further down in the tree than previously suggested, and shows a polytomy with Blasisaurus and Arenyisaurus. This study also indicates that Nipponosaurus is a valid taxon because it possesses unique characters within the Lambeosaurinae (presence of massive surangular anterodorsal process, presence of lateral shelf of the dentary, and a relatively short ulna), which are independent of ontogeny. [ABSTRACT FROM AUTHOR]

Abstract: Gigantspinosaurus sichuanensis is one of the six Stegosauria genera discovered from the Sichuan basin, which preserves the first skin impressions of stegosaurs around the world and a huge pair of ‘comma’ ‐shaped parascapular spines kept in situ, and being named after the latter feature. The holotype was firstly named and reported in an abstract of a lecture by Ouyang, 1992, since when it has never been detailed studied and the taxonomic position of Gigantspinosaurus is also vague. The morphological redescription shows that G. sichuanensis is a medium‐sized stegosaur, with external mandibular foramen developed. The ratio of femur to humerus is large, and the intersacral fenestrae are big. According to the wear degree of teeth, the holotype of G. sichuanensis is regarded as an adult individual. On the basis of the recent data matrix of stegosaurs and the characters revisions of G. sichuanensis, its phylogenetic position has been determined again. By our detailed morphological and phylogenetic analysis, G. sichuanensis is considered to inherit some primitive traits, but it is more derived than Huayangosaurus, and located in a transitional position between Huayangosaurus and Tuojiangosaurus, as a kind of evolved stegosaurs. The ancestors of Stegosauria are small and quadruped, with primitive ornithopod‐like skull, and grow leaf‐shaped teeth, a large number of bone plates. [ABSTRACT FROM AUTHOR]

The use of drones in the exploration and documentation of track surfaces in steep terrain, otherwise only accessible by time intensive climbing activity, is tested. Location is the Nanquan site, one of many now known footprint localities from the Lower Cretaceous Dasheng Group that has been recently exposed by local industrial excavation. It reveals an ichnofauna of sauropod, theropod, and ornithopod tracks and trackways occurring at multiple stratigraphic levels (at least 10) in a thin sequence of fine grained purple mudstones with thin sandstone units that are steeply inclined by >45°. It was therefore necessary and most efficient to map the track-bearing surfaces using drone photography. The majority of track-bearing levels reveal sauropod tracks (cf. Brontopodus , cf. Parabrontopodus ), which on some surfaces are very abundant. Large theropod tracks (cf. Grallator ) and ornithopod tracks ( Caririchnium ) also occur, but only on single horizons. The ichnofauna is evidence of repeated activity by large dinosaurs in a fluvio-lacustrine floodplain setting susceptible to periodic desiccation. The Naquan site forms part of an extensive Dasheng Group outcrop belt with multiple tracks sites, most of these containing multiple track-bearing levels. As a result of the investigation, drone techniques can be recommended as an additional tool for quick documentation, in order to get a general overview and map of the track surface. Details are relatively distinct on the achieved photographs, however, a precise study still needs direct examination and documentation by classical outline drawings or photogrammetry. [ABSTRACT FROM AUTHOR]

Ouranosaurus nigeriensis is an iconic African dinosaur taxon that has been described on the basis of two nearly complete skeletons from the Lower Cretaceous Gadoufaoua locality of the Ténéré desert in Niger. The entire holotype and a few bones attributed to the paratype formed the basis of the original description by Taquet (1976). A mounted skeleton that appears to correspond to O. nigeriensis has been on public display since 1975, exhibited at the Natural History Museum of Venice. It was never explicitly reported whether the Venice specimen represents a paratype and therefore, the second nearly complete skeleton reported in literature or a third unreported skeleton. The purpose of this paper is to disentangle the complex history of the various skeletal remains that have been attributed to Ouranosaurus nigeriensis (aided by an unpublished field map of the paratype) and to describe in detail the osteology of the Venice skeleton. The latter includes the paratype material (found in 1970 and collected in 1972), with the exception of the left femur, the right coracoid and one manus ungual phalanx I, which were replaced with plaster copies, and (possibly) other manus phalanges. Some other elements (e.g., the first two chevrons, the right femur, the right tibia, two dorsal vertebrae and some pelvic bones) were likely added from other individual/s. The vertebral column of the paratype was articulated and provides a better reference for the vertebral count of this taxon than the holotype. Several anatomical differences are observed between the holotype and the Venice specimen. Most of them can be ascribed to intraspecific variability (individual or ontogenetic), but some are probably caused by mistakes in the preparation or assemblage of the skeletal elements in both specimens. The body length of the Venice skeleton is about 90% the linear size of the holotype. Osteohistological analysis (the first for this taxon) of some long bones, a rib and a dorsal neural spine reveals that the Venice specimen is a sub-adult; this conclusion is supported by somatic evidence of immaturity. The dorsal ‘sail’ formed by the elongated neural spines of the dorsal, sacral and proximal caudal vertebrae characterizes this taxon among ornithopods; a display role is considered to be the most probable function for this bizarre structure. Compared to the mid-1970s, new information from the Venice specimen and many iguanodontian taxa known today allowed for an improved diagnosis of O. nigeriensis.

A new small-bodied ornithopod dinosaur, Diluvicursor pickeringi, gen. et sp. nov., is named from the lower Albian of the Eumeralla Formation in southeastern Australia and helps shed new light on the anatomy and diversity of Gondwanan ornithopods. Comprising an almost complete tail and partial lower right hindlimb, the holotype (NMV P221080) was deposited as a carcass or body-part in a log-filled scour near the base of a deep, high-energy river that incised a faunally rich, substantially forested riverine floodplain within the Australian-Antarctic rift graben. The deposit is termed the 'Eric the Red West Sandstone.' The holotype, interpreted as an older juvenile ~1.2 m in total length, appears to have endured antemortem trauma to the pes. A referred, isolated posterior caudal vertebra (NMV P229456) from the holotype locality, suggests D. pickeringi grew to at least 2.3 m in length. D. pickeringi is characterised by 10 potential autapomorphies, among which dorsoventrally low neural arches and transversely broad caudal ribs on the anterior-most caudal vertebrae are a visually defining combination of features. These features suggest D. pickeringi had robust anterior caudal musculature and strong locomotor abilities. Another isolated anterior caudal vertebra (NMV P228342) from the same deposit, suggests that the fossil assemblage hosts at least two ornithopod taxa. D. pickeringi and two stratigraphically younger, indeterminate Eumeralla Formation ornithopods from Dinosaur Cove, NMV P185992/P185993 and NMV P186047, are closely related. However, the tail of D. pickeringi is far shorter than that of NMV P185992/P185993 and its pes more robust than that of NMV P186047. Preliminary cladistic analysis, utilising three existing datasets, failed to resolve D. pickeringi beyond a large polytomy of Ornithopoda. However, qualitative assessment of shared anatomical features suggest that the Eumeralla Formation ornithopods, South American Anabisetia saldiviai and Gasparinisaura cincosaltensis, Afro-Laurasian dryosaurids and possibly Antarctic Morrosaurus antarcticus share a close phylogenetic progenitor. Future phylogenetic analysis with improved data on Australian ornithopods will help to test these suggested affinities. [ABSTRACT FROM AUTHOR]

Zhucheng, located in eastern Shandong Province, China, is well-known for its abundant Early Cretaceous dinosaur footprints and Late Cretaceous dinosaur bone fossils. Recently, Lockley et al. (2015) presented a sketch study on the Huanglonggou tracksite in the Zhucheng area, and critically commented on our paper (H. Xu et al., 2013), which conducted a detailed and comprehensive study of the tracksite. Here, we demonstrate that some of their assumptions and comments on our work are subjective and incorrect. Tracks at the Huanglonggou tracksite, including a dominant theropod (large theropod, Grallator yangi / Paragrallator , Corpulentapus lilasia ), and subordinate sauropod, suspected ornithopod, and turtle tracks were preserved in the Yangjiazhuang Formation with estimated ages of 129 to 122 Ma, rather than in the Longwangzhuang Formation as proposed by Lockley and his associates. Contrary to Lockley et al. (2015), our mapping of the Huanglonggou tracksite exhibits the previous work by Li et al. (2011) and focuses on the 50 well-preserved trackways and their orientations. Based on the stride length to footprint size index diagram and the Grallator–Anchisauripus–Eubrontes (GAE) plexus, our statistical constraints on the three species of theropods are better than those of Lockley et al. (2015). Lockley argued that tracks at the site were preserved on at least five levels, of which the majority on level 4 were of excellent preservation. In fact, the tracks identified throughout the site have been from only one level. The false appearance of multiple levels is interpreted as the result of sedimentation at the shoreline and differential excavation of the tracksite. [ABSTRACT FROM AUTHOR]

Several new Early Cretaceous tracksites from the Lower Cretaceous Xiagou Formation of Gansu Province (China) with tracks of large sauropods and ornithopods are described. Previously reported bird tracks were missing due to human negligence. The studied specimens are preserved as impressions and shallow and deep natural track casts. These dinosaur tracks are first reported from the Jiuquan area in the Changma Basin, matching well with the skeletal record of diverse non-avian dinosaur-bird faunas of this region. Moreover, they add new data to the dinosaur ichnofaunas of the Lanzhou-Minhe Basin (Gansu Province) and indicate a wide distribution of dinosaur-bird assemblages in the Early Cretaceous. Regarding morphology, sauropod, and ornithopod tracks from the Lanzhou-Minhe Basin and the Jiuquan area are very similar to each other. Titanosauriform trackmakers are assumed for the sauropod tracks and possibly iguanodontids have left the large, tridactyl ornithopod tracks. Of particular interest are well-preserved, deep natural track casts of large ornithopods and sauropods preserving ridges and grooves as well as striation marks on the lateral sides of the casts that allow the reconstruction of complex pathways of the foot within the substrate. One particular sauropodpes–manustrack cast even indicates lateral and vertical sliding within the sediment because of the presence of “double impressions of digits” on the bottom. [ABSTRACT FROM PUBLISHER]

Fieldwork in the Upper Cretaceous (Maastrichtian) Al-Khod Conglomerates in the Sultanate of Oman led to the discovery of a large bone fragment tentatively identified as a partial distal left humerus of a sauropod and an ornithopod dorsal vertebra. The very fragmentary state of preservation of the dorsal vertebra makes specific attribution difficult, but it shows remarkable similarities to the rhabdodontid dinosaurs Rhabdodon and Zalmoxes.

The systematic relationships of taxa traditionally referred to as ‘basal ornithopods’ or ‘hypsilophodontids’ remain poorly resolved since it was discovered that these taxa are not a monophyletic group, but rather a paraphyletic set of neornithischian taxa. Thus, even as the known diversity of these taxa has dramatically increased over the past two decades, our knowledge of their placement relative to each other and the major ornithischian subclades remained incomplete. This study employs the largest phylogenetic dataset yet compiled to assess basal ornithischian relationships (255 characters for 65 species level terminal taxa). The resulting strict consensus tree is the most well-resolved, stratigraphically consistent hypothesis of basal ornithischian relationships yet hypothesized. The only non-iguanodontian ornithopod (=basal ornithopod) recovered in this analysis is Hypsilophodon foxii. The majority of former ‘hypsilophodontid’ taxa are recovered within a single clade (Parksosauridae) that is situated as the sister-taxon to Cerapoda. The Parksosauridae is divided between two subclades, the Orodrominae and the Thescelosaurinae. This study does not recover a clade consisting of the Asian taxa Changchunsaurus, Haya, and Jeholosaurus (=Jeholosauridae). Rather, the former two taxa are recovered as basal members of Thescelosaurinae, while the latter taxon is recovered in a clade with Yueosaurus near the base of Neornithischia.The endemic South American clade Elasmaria is recovered within the Thescelosaurinae as the sister taxon to Thescelosaurus. This study supports the origination of Dinosauria and the early diversification of Ornithischia within Gondwana. Neornithischia first arose in Africa by the Early Jurassic before dispersing to Asia before the late Middle Jurassic, where much of the diversification among non-cerapodan neornithischians occurred. Under the simplest scenario the Parksosauridae originated in North America, with at least two later dispersals to Asia and one to South America. However, when ghost lineages are considered, an alternate dispersal hypothesis has thescelosaurines dispersing from Asia into South America (via North America) during the Early Cretaceous, then back into North America in the latest Cretaceous. The latter hypothesis may explain the dominance of orodromine taxa prior to the Maastrichtian in North America and the sudden appearance and wide distribution of thescelosaurines in North America beginning in the early Maastrichtian. While the diversity of parksosaurids has greatly increased over the last fifteen years, a ghost lineage of over 40 myr is present between the base of Parksosauridae and Cerapoda, indicating that much of the early history and diversity of this clade is yet to be discovered. This new phylogenetic hypothesis provides a comprehensive framework for testing further hypotheses regarding evolutionary patterns and processes within Ornithischia.

Osteopathy from derived hadrosauroids has been extensively studied. However, little work has been done in the basal members of this group. Only two brief notes have recorded three examples of osteopathy in the basal hadrosauroids in Bactrosaurus, Gilmoreosaurus and Jeyawati. In the present manuscript, we found in the holotype of the basal hadrosauroid Huehuecanauhtlus tiquichensis (IGM 6253) from Mexico two dorsal ribs and a dorsal vertebra with unusual pathologic conditions. The injuries are described as possible premortem or perimortem anterior rib fracture, associated with a singular sclerosis and costovertebral ankyloses which probably originated by spinal and rib osteomyelitis. The vertebral lesion caused direct damage to the nervous system and possible back pain. This study represents the first study of palaeopathology in a Mexican hadrosauroid in which the bone abnormalities are extensively compared with previous studies and described in detail, their origins are interpreted, and the health implications for the individual are considered. [ABSTRACT FROM AUTHOR]

Uppermost Cretaceous (Campanian-Maastrichtian) large ornithopod tracks are scarce in Gondwana. This record is limited to few citations in the northern Argentina, Peru and possibly Bolivia, although their ichnological affinities are still under discussion. Recently, a new vertebrate tracksite with large ornithopod tracks has been found in the Maimará locality, Jujuy province, Argentina, from the Yacoraite Formation (Maastrichtian-Danian). The best preserved track is characterized by having large and bilobed heel impression and wide and short digit impressions with blunt claw marks. This record represents the unambiguous record of large ornithopod tracks in Gondwana in the Uppermost Cretaceous, and its features allow classifying it as Hadrosauropodus . Previously, this ichnotaxon had exclusively Laurasian distribution. Therefore, this record is the first evidence of Hadrosauropodus from Gondwana expanding the geographic range of this ichnogenus. A member of Hadrosauridae is reinforced as possible trackmaker of the Hadrosauropodus tracks. Uppermost Cretaceous hadrosaurid dinosaurs are scarce in Gondwana, being the record limited to Patagonia, La Pampa province and Antarctica. Therefore, the Maimará tracks increase the knowledge of this kind of dinosaur from Gondwana. [ABSTRACT FROM AUTHOR]

At least four parallel trackways of medium-sized and robust ornithopods are described from the Upper Jurassic Tereñes tracksite in Asturias (N. Spain). While the tracks and trackways of small and gracile ornithopods are common in the Jurassic record, large ornithopods are very rare in this period. Ornithopod gregarious behavior has been recorded from many Cretaceous ichnoassemblages, but there are few examples from the Jurassic, and these always relate to small individuals. The Asturian tracks are quite different from known ichnogenera, but they are not sufficiently well preserved to propose a new one. Medium-large Jurassic ornithopods with robust feet such asDraconyxorCumnoriaare the best candidates to be the trackmakers. [ABSTRACT FROM AUTHOR]

Disarticulated and incomplete remains from a new diminutive ornithopod are described. They come from the Cameros Basin in the north of Spain and were collected from the red clays of the Castrillo de la Reina Formation, ranging from Upper Barremian to Lower Aptian. The new ornithopod described here is slender and one of the smallest ever reported. An up-to-date phylogenetic analysis recovers this taxon as a basal iguanodontian. Its unique combination of characters makes it more derived than slender ornithopods like Hyphilophodon and Gasparinisaura, and bring very interesting insights into the basal iguanodontian phylogeny. Though possessing a minimum of three premaxillary teeth, this taxon also bears an extensor ilio-tibialis groove on the distal part of its femur. Moreover, its dentary and maxillary teeth are unique, remarkably similar to those regarded as having a “rhabdomorphan” affinity. This unknown taxon is suggested to be a stem taxon within Rhabdodontidae, a successful clade of basal iguanodonts from the Late Cretaceous of Europe. The Gondwanan ornithopods share the strongest affinities with this family, and we confirm Muttaburrasaurus as a sister taxon of the Rhabdodontidae within a newly defined clade, the Rhabdodontomorpha. [ABSTRACT FROM AUTHOR]

The fossil record of ornithischian dinosaurs from Africa is particularly scarce and limited to a few historic localities. In this study we describe new ornithischian remains from the Albian deposits of southern Tunisia (Tataouine Governorate), represented by isolated teeth of large-bodied iguanodontians. Teeth display a wide, diamond-shaped crown with a primary ridge dividing the occlusal surface in two unequal parts and two or more secondary ridges. Hook-like denticles are present on both mesial and distal crown margins and do not display mammillae. In overall morphology, specimens are comparable to those of many Early Cretaceous basal hadrosauriforms, including isolated ornithopodan teeth from comparably-aged levels of Niger. Transversal sections of the crowns permitted identification of dental tissues, which include a thick enamel, and well developed longitudinal and transverse giant tubules. Their relative extents appear to be related to the size, thus developmental age, of the tooth. Teeth are representative of the Oum ed Diab Member, a unit characterized by coastal deposits accumulated under arid to xeric climatic conditions and dominated by fish, crocodilians, and hydraulically transported rebbachisaurid and spinosaurid remains. Sedimentological data and preservation bias strongly support selective taphonomic causes for the fossil distribution of ornithischians in southern Tunisia questioning the purported geographic and paleoecologic distribution of isolated Saharan dinosaurs. [ABSTRACT FROM AUTHOR]