ABSTRACT The earliest ornithischian dinosaurs were small bipeds that possessed the derived, retroverted pubis is synapomorphic for clade. Their forelimbs modified grasping. Subsequently, ornithischians radiated into numerous body shapes and sizes. Three lineages independently evolved large size quadrupedality, requiring profound changes to osteology myology of locomotor apparatus. Using comparisons with extinct archosaurian outgroups, as well extant birds crocodilians, we reconstruct basal...

Synopsis Stegosauria is a clade of ornithischian dinosaurs characterised by bizarre array dermal armour extending, in two parasagittal rows, from the cervical region to end tail. Although Stegosaurus one most familiar all dinosaurs, little known regarding evolutionary history this clade. Alpha‐level taxonomic revision proposed stegosaur taxa shows that 11 species stego‐saur can be regarded as valid on basis autapomorphies. These are: Dacentrurus armatus and Loricatosaurus priscus (gen. nov.)...

Ankylosauria is a diverse clade of quadrupedal ornithischian dinosaurs whose remains are known from Middle Jurassic to latest Cretaceous sediments worldwide. Despite long history research, ankylosaur interrelationships remain poorly resolved and existing cladistic analyses suffer limited character taxon sampling. Here, we present the most comprehensive phylogenetic analysis group attempted date. The traditional ankylosaurid–nodosaurid dichotomy maintained. Ankylosauridae forms well-resolved...

The evolution of quadrupedality from bipedal ancestors is an exceptionally rare transition in tetrapod evolution, but it has occurred several times within the herbivorous dinosaur clade Ornithischia.Stegosauria, Ankylosauria, and Ceratopsidae are all uncontroversially quadrupedal, while basal ornithischians ornithopods bipedal.However, stance iguanodontian ornithopods, including hadrosaurs, non-ceratopsid ceratopsians debated because robust osteological correlates have not been identified.We...

Abstract Exceptionally preserved organic remains are known throughout the vertebrate fossil record, and recently, evidence has emerged that such soft tissue might contain original components. We examined samples from eight Cretaceous dinosaur bones using nano-analytical techniques; not exceptionally show no external indication of tissue. In one sample, we observe structures consistent with endogenous collagen fibre displaying ∼67 nm banding, indicating possible preservation quaternary...

ABSTRACT Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from ancestors has only two other occasions, making this one rarest locomotory transitions tetrapod evolutionary history. The osteological and myological changes associated these have recently been documented, biomechanical consequences remain to be examined. Here, we review...

A new genus and species of non-hadrosaurid hadrosauriform dinosaur, Brighstoneus simmondsi gen. et sp. nov., is described from the Lower Cretaceous Wessex Formation Isle Wight. The taxon has two autapomorphies, a nasal having modest bulla with convex sides, primary accessory ridges on lingual aspect maxillary crown. dentary at least 28 alveolar positions, which highest number recorded in an ornithopod non-parallel sided alveoli, creating character combination that unique within Iguanodontia....

Abstract Four phases of cross‐cutting tunnel valleys imaged on 3‐D seismic datasets are mapped within the Middle–Late Pleistocene succession central North Sea basin (Witch Ground area). In plan form complex anastomosing networks, with tributary joining main at high angles. The have widths ranging from 250 to 2300 m, and base shoulder relief varying between 30 155 irregular long‐axis profiles characteristic erosion by water driven glaciostatic pressures. youngest phase smaller a thinner...

Stegosaurian dinosaurs have a quadrupedal stance, short forelimbs, necks, and are generally considered to be low browsers. A new stegosaur, Miragaia longicollum gen. et sp. nov., from the Late Jurassic of Portugal, has neck comprising at least 17 cervical vertebrae. This is eight additional vertebrae when compared with ancestral condition seen in basal ornithischians such as Scutellosaurus. higher count than most iconically long-necked sauropod dinosaurs. Long length been achieved by...

Convergent morphologies are thought to indicate functional similarity, arising because of a limited number evolutionary or developmental pathways. Extant taxa displaying convergent used as analogues assess function in extinct with similar characteristics. However, studies extant have shown that similarity can arise from differing morphologies, calling into question the paradigm form and closely related. We test hypothesis skeletal morphology indicates fossil record using ornithischian...

Estimates of body mass often represent the founding assumption on which biomechanical and macroevolutionary hypotheses are based. Recently, a scaling equation was applied to newly discovered titanosaurian sauropod dinosaur ( Dreadnoughtus ), yielding 59 300 kg estimate for this animal. Herein, we use modelling approach examine plausibility . We find that is highly implausible demonstrate masses above 40 000 require high densities expansions soft tissue volume outside skeleton several times...

Although Stegosaurus is one of the most iconic dinosaurs, well-preserved fossils are rare and as a consequence there still much that remains unknown about taxon. A new, exceptionally complete individual affords opportunity to describe anatomy in detail for first time over century, enables additional comparisons with other stegosaurian dinosaurs. The new specimen from Red Canyon Ranch Quarry, near Shell Wyoming, appears have been so well preserved because it was buried rapidly pond or body...

Abstract The stegosaurs are some of the most easily recognizable dinosaurs, but surprisingly rare as fossils. Consequently much remains unknown about their palaeobiology, and every new stegosaurian find contributes to our understanding evolution clade. Since last attempt examine evolutionary relationships Stegosauria, specimens have come light, including complete individual Stegosaurus ever found, taxa been described and, perhaps importantly, methods for analysis cladistic datasets produced....

Abstract The advent of palaeontological occurrence databases has allowed for detailed reconstruction and analyses species richness through deep time. While a substantial literature evolved ensuring that taxa are fairly counted within between different time periods, how itself is divided received less attention. Stage‐level or equal‐interval age bins have frequently been used regional global studies in vertebrate palaeontology. However, when assessing diversity at scale, these resolutions can...

We describe a new small-bodied coelophysoid theropod dinosaur,

Abstract Body size and shape play fundamental roles in organismal function it is expected that animals may possess body proportions are well-suited to their ecological niche. Tetrapods exhibit a diverse array of shapes, but date this diversity its relationship ecology have not been systematically quantified. Using whole-body skeletal models 410 extinct extant tetrapods, we show allometric relationships vary across individual segments thereby yielding changes overall as increases. However,...

Among living crocodylians, alligatoroids exhibit a wide range of body sizes and biogeographic distribution that spans tropical-to-subtropical climates. The fossil record alligatoroids, however, reveals even greater diversity, including multiple examples gigantism broader extends into polar latitudes. Osteohistological studies on extant show alligators caimans both seasonal growth, with roughly comparable growth rates. However, diverged from one another over 60 million years ago; the dearth...

ABSTRACT The fossil record of dinosaurs in Scotland mostly comprises isolated highly fragmentary bones from the Great Estuarine Group Inner Hebrides (Bajocian–Bathonian). Here we report first definite dinosaur body ever found (historically), having been discovered 1973, but not collected until 45 years later. It is and most complete partial skeleton currently known Scotland. NMS G.2023.19.1 was recovered a challenging foreshore location Isle Skye, transported to harbour semi-rigid inflatable...

The cerapodan dinosaurs were an ornithischian clade that achieved a global distribution in the Cretaceous Period. ichnological record suggests these had evolved by Middle Jurassic, but only single body fossil, isolated femur from Callovian of UK, is known this interval. In order to elucidate early stages evolution and help resolve many phylogenetic inconsistencies clade, new specimens, particularly historically undersampled localities, are needed. Herein, we report proximal dinosaur...

Abstract Ornithischia (the ‘bird‐hipped’ dinosaurs) encompasses bipedal, facultative quadrupedal and taxa. Primitive ornithischians were small bipeds, but large body size obligate quadrupedality evolved independently in all major ornithischian lineages. Numerous pelvic hind limb features distinguish from the majority of other non‐avian dinosaurs. However, some these features, notably a retroverted pubis elongate iliac preacetabular process, appeared convergently maniraptoran theropods,...

The most primitive ornithischian dinosaurs were small bipeds, but quadrupedality evolved three times independently in the clade. transition to from bipedal ancestors is rare history of terrestrial vertebrate evolution, and extant analogues do not exist. Constraints imposed on quadrupedal ornithischians by their ancestral bauplan remain unexplored, consequently, debate continues about stance gait. For example, it has been proposed that some could run, while others consider none...

Body mass is a key biological variable, but difficult to assess from fossils. Various techniques exist for estimating body skeletal parameters, few studies have compared outputs different methods. Here, we apply several estimation methods an exceptionally complete skeleton of the dinosaur Stegosaurus. Applying volumetric convex-hulling technique digital model Stegosaurus, estimate 1560 kg (95% prediction interval 1082-2256 kg) this individual. By contrast, bivariate equations based on limb...

Abstract The earliest crocodylomorphs, known as non‐crocodyliform first appeared during the Late Triassic. In contrast to extant crocodylians, which are all semi‐aquatic, early crocodylomorphs represent terrestrial taxa with a fully erect posture and in most cases small body size. Their gracile skeletons suggest an active mode of life, possibly similar contemporaneous, bipedal theropod dinosaurs. Despite this remarkable plan, postcranial morphology has rarely been documented detail,...

The early Mesozoic fossil fauna collected from the Lower Lufeng Formation of Yunnan Province, China, has attracted considerable interest and attention since its discovery in late 1930s. Its importance reflected a combination comparatively remote geographical position and, more particularly, similarities compared with approximately contemporary discoveries Europe, North South America, southern Africa. fragmentary poorly preserved ornithischian dinosaur Tatisaurus oehleri was described 1965...