Basal Ornithopoda

Norman, David; Sues, Hans‐Dieter; Witmer, Lawrence M.; Coria, Rodolfo A.

doi:10.1525/california/9780520242098.003.0021

Cited by 124 publications

(293 citation statements)

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“…1B). This number is similar to that seen in many other ornithopods (Norman, 2004;Norman et al, 2004), but much lower than those recorded for the exceptionally long tails of Leaellynasaura (>70 caudal vertebrae; Herne, 2009) and Tenontosaurus (60-65 caudal vertebrae: Forster, 1990). …”

Section: Discussionsupporting

confidence: 81%

A new specimen of Valdosaurus canaliculatus (Ornithopoda: Dryosauridae) from the Lower Cretaceous of the Isle of Wight, England

Barrett¹

2016

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The anatomy of Valdosaurus canaliculatus is incompletely known and until recently was based exclusively upon the holotype femora. Additional discoveries from the Wessex Formation (Barremian) of the Isle of Wight during the past decade have considerably expanded the amount of material available and offered insights into the morphology of the vertebral column and pelvis. However, all of these specimens consist primarily of hind limb material. Here, I describe a newly discovered individual of this taxon, the most complete yet found, which was found in articulation and includes a partial dorsal series, an almost complete tail, pelvic material, and both hind limbs. Although the specimen is partially crushed it offers new information on the anatomy of Valdosaurus, facilitating comparisons with other dryosaurid taxa.

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Section: Discussionsupporting

confidence: 81%

A new specimen of Valdosaurus canaliculatus (Ornithopoda: Dryosauridae) from the Lower Cretaceous of the Isle of Wight, England

Barrett¹

2016

MMV

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“…Gow (1990) also described an additional isolated maxilla, referring it and the holotypic maxilla of Lanasaurus scalpridens to Lycorhinus angustidens. The status of Lanasaurus scalpridens as a junior synonym of Lycorhinus angustidens has been accepted by later authors (Norman et al 2004; this study), although recently Porro et al (2010) and Norman et al (2011) provisionally retained Lanasaurus scalpridens as a distinct genus and species.…”

Section: Taxonomic Resolutionmentioning

confidence: 68%

“…He also argued that these two heterodontosaurids are generically distinct from Thulborn's species Lycorhinus consors (NHMUK RU B54) and specimen NHMUK RU A100, placing the latter two specimens in a new genus as Abrictosaurus consors (Table 2). Weishampel (1984) and subsequent taxonomic compilations (Norman et al 2004) accepted Hopson's assignment of NHMUK RU A100 to A. consors ), whereas Gow (1990) and this review suggest that NHMUK RU A100 should be assigned to L. angustidens (Table 2). Gow (1990) also described an additional isolated maxilla, referring it and the holotypic maxilla of Lanasaurus scalpridens to Lycorhinus angustidens.…”

Section: Taxonomic Resolutionmentioning

confidence: 74%

Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs

Sereno

2012

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Heterodontosaurids comprise an important early radiation of small-bodied herbivores that persisted for approximately 100 My from Late Triassic to Early Cretaceous time. Review of available fossils unequivocally establishes Echinodon as a very small-bodied, late-surviving northern heterodontosaurid similar to the other northern genera Fruitadens and Tianyulong. Tianyulong from northern China has unusual skeletal proportions, including a relatively large skull, short forelimb, and long manual digit II. The southern African heterodontosaurid genus Lycorhinus is established as valid, and a new taxon from the same formation is named Pegomastax africanus gen. n., sp. n. Tooth replacement and tooth-to-tooth wear is more common than previously thought among heterodontosaurids, and in Heterodontosaurus the angle of tooth-to-tooth shear is shown to increase markedly during maturation. Long-axis rotation of the lower jaw during occlusion is identified here as the most likely functional mechanism underlying marked tooth wear in mature specimens of Heterodontosaurus. Extensive tooth wear and other evidence suggests that all heterodontosaurids were predominantly or exclusively herbivores. Basal genera such as Echinodon, Fruitadens and Tianyulong with primitive, subtriangular crowns currently are known only from northern landmasses. All other genera except the enigmatic Pisanosaurus have deeper crown proportions and currently are known only from southern landmasses.

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“…Taxa erroneously thought to be dinosaurs, but not ornithischians, are listed in Table 3 Gow, 1975;Hopson, 1975;Santa Luca et al, 1976;Santa Luca, 1980;Gow, 1990;Butler et al, 2008b). Recent reviews consider only three of the heterodontosaurid genera to be valid (Weishampel and Witmer, 1990;Norman et al, 2004c). However, the taxonomy of the Southern African heterodontosaurids is problematic: additional taxa may be present (RJB pers.…”

Section: Early Jurassic Ornithischians -Fossil Record and Distributionmentioning

confidence: 99%

The origin and early radiation of dinosaurs

Brusatte

Nesbitt

Irmis

et al. 2010

Earth-Science Reviews

242

214

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Dinosaurs were remarkably successful during the Mesozoic and one subgroup, birds, remain an important component of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been the subject of intense debate, comparatively little attention has been given to the origin and early evolution of dinosaurs during the Late Triassic and Early Jurassic, one of the most important evolutionary radiations in earth history. Our understanding of this keystone event has dramatically changed over the past 25 years, thanks to an influx of new fossil discoveries, reinterpretations of long-ignored specimens, and quantitative macroevolutionary analyses that synthesize anatomical and geological data. Here we provide an overview of the first 50 million years of dinosaur history, with a focus on the large-scale patterns that characterize the ascent of dinosaurs from a small, almost marginal group of reptiles in the Late Triassic to the preeminent terrestrial vertebrates of the Jurassic and Cretaceous. We provide both a biological and geological background for early dinosaur history. Dinosaurs are deeply nested among the archosaurian reptiles, diagnosed by only a small number of characters, and are subdivided into a number of major lineages. The first unequivocal dinosaurs are known from the late Carnian of South America, but the presence of their sister group in the Middle Triassic implies that dinosaurs possibly originated much earlier. The three major dinosaur lineages, theropods, sauropodomorphs, and ornithischians, are all known from the Triassic, when continents were joined into the supercontinent Pangaea and global climates were hot and arid. Although many researchers have long suggested that dinosaurs outcompeted other reptile groups during the Triassic, we argue that the ascent of dinosaurs was more of a matter of contingency and opportunism. Dinosaurs were overshadowed in most Late Triassic ecosystems by crocodile-line archosaurs and showed no signs of outcompeting their rivals. Instead, the rise of dinosaurs was a two-stage process, as dinosaurs expanded in taxonomic diversity, morphological disparity, and absolute faunal abundance only after the extinction of most crocodile-line reptiles and other groups.

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Basal Ornithopoda

Cited by 124 publications

References 0 publications

A new specimen of Valdosaurus canaliculatus (Ornithopoda: Dryosauridae) from the Lower Cretaceous of the Isle of Wight, England

A new specimen of Valdosaurus canaliculatus (Ornithopoda: Dryosauridae) from the Lower Cretaceous of the Isle of Wight, England

Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs

The origin and early radiation of dinosaurs

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