Joseph A. Bonsor

University of Bath

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Paul M. Barrett

Natural History Museum

Susannah C. R. Maidment

Natural History Museum

Thomas J. Raven

Natural History Museum

Kimberley E. J. Chapelle

University of the Witwatersrand

David J. Button

Australian Nuclear Science and Technology Organisation

Natalie Cooper

Natural History Museum

Simon J. Braddy

Alibaba Group (China)

João V. Leite

Natural History Museum

Mia Wroe

University of Birmingham

Richard J. Butler

University of Birmingham

Cooperative Institutions

Natural History Museum

University of Birmingham

Stony Brook University

Google (United States)

University of the Witwatersrand

University of Fribourg

American Museum of Natural History

University of Bristol

Museum für Naturkunde

Universidade Federal do Paraná

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A revision of the non-avian dinosaurs ‘Eucercosaurus tanyspondylus’ and ‘Syngonosaurus macrocercus’ from the Cambridge Greensand, UK

Cretaceous Research (2020)

Paul M. Barrett Joseph A. Bonsor

Cenomanian

Tetrapod (structure)

Sauropoda

10.1016/j.cretres.2020.104638

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Citations (3)

THE OSTEOLOGY OF THE HOLOTYPE OF THE BRITISH IGUANODONTIAN DINOSAURMANTELLISAURUS ATHERFIELDENSIS

Monographs of the Palaeontographical Society (2023)

Joseph A. Bonsor Jeremy A. F. Lockwood João V. Leite Amy Scott-Murray Susannah C. R. Maidment

Iguanodontian dinosaurs are known from Middle Jurassic to Late Cretaceous deposits worldwide and are historically important because they include the first fossils to be identified as giant extinct reptiles that later became known as dinosaurs. Due to historical taxonomic practices and the fragmentary nature of many specimens, discoveries from the 19th century were referred to Iguanodon with little appraisal, resulting in the genus becoming something of a 'wastebasket taxon'. Reinterpretations of holotype specimens are an important step in attempting to understand the evolutionary history of iguanodontian dinosaurs. Here, we redescribe the holotype of Mantellisaurus atherfieldensis, one of the most complete British dinosaur specimens, from the Barremian/Aptian of the Isle of Wight, UK, and assess its phylogenetic position. We find that Mantellisaurus atherfieldensis is a valid taxon distinct from the genus Iguanodon based on three autapomorphies of the premaxilla, maxilla, and scapula, and resolves as an early diverging hadrosauroid styracosternan, representing an important step in the evolutionary history of the ornithopods.

Autapomorphy

Osteology

Premaxilla

Theropoda

Phyletic gradualism

10.1080/02693445.2023.2234156

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Citations (6)

OSTEOLOGY AND RELATIONSHIPS OF CUMNORIA PRESTWICHII (ORNITHISCHIA: ORNITHOPODA) FROM THE LATE JURASSIC OF OXFORDSHIRE, UK

Figshare (2023)

Susannah C. R. Maidment Kimberley E. J. Chapelle Joseph A. Bonsor David J. Button Paul M. Barrett

The iguanodontian dinosaurs have a fossil record that extends from the Middle Jurassic to the end of the Cretaceous, by which time they had diversified to become the dominant herbivores of Laurasian ecosystems. They are historically important because fossils of British iguanodontians were among the first to be recognised as the gigantic reptiles that formed the basis for naming Dinosauria. However, the early stages of their evolution remain obscure because of a sparse fossil record, and taxonomic and systematic controversies among non-hadrosaurid iguanodontians abound. In order to shed light on the early stages of iguanodontian evolution, new discoveries and re-interpretations of historic specimens are crucial. Here, we redescribe the Late Jurassic early-branching iguanodontian Cumnoria prestwichii from the Kimmeridge Clay Formation of Oxfordshire, UK, and assess its phylogenetic position. We find that Cumnoria is distinct from the North American taxon Camptosaurus, with which it was previously synonymized, and is valid, possessing two autapomorphies of the pectoral girdle. We recover its phylogenetic position as a non-ankylopollexian iguanodontian. Cumnoria represents one of just four valid ornithopod taxa from the Jurassic of Europe.

Osteology

10.6084/m9.figshare.21940120

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Citations (0)

Dinosaur diversification rates were not in decline prior to the K-Pg boundary

Royal Society Open Science (2020)

Joseph A. Bonsor Paul M. Barrett Thomas J. Raven Natalie Cooper

Determining the tempo and mode of non-avian dinosaur extinction is one of the most contentious issues in palaeobiology. Extensive disagreements remain over whether their extinction was catastrophic and geologically instantaneous or the culmination of long-term evolutionary trends. These conflicts have arisen due to numerous hierarchical sampling biases in the fossil record and differences in analytical methodology, with some studies identifying long-term declines in dinosaur richness prior to the Cretaceous-Palaeogene (K-Pg) boundary and others proposing continued diversification. Here, we use Bayesian phylogenetic generalized linear mixed models to assess the fit of 12 dinosaur phylogenies to three speciation models (null, slowdown to asymptote, downturn). We do not find strong support for the downturn model in our analyses, which suggests that dinosaur speciation rates were not in terminal decline prior to the K-Pg boundary and that the clade was still capable of generating new taxa. Nevertheless, we advocate caution in interpreting the results of such models, as they may not accurately reflect the complexities of the underlying data. Indeed, current phylogenetic methods may not provide the best test for hypotheses of dinosaur extinction; the collection of more dinosaur occurrence data will be essential to test these ideas further.

Extinction (optical mineralogy)

Macroevolution

Genetic algorithm

10.1098/rsos.201195

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Citations (26)

The Early Devonian eurypteridLeiopterella tetlieifrom Arctic Canada

Canadian Journal of Earth Sciences (2021)

Simon J. Braddy Jason A. Dunlop Joseph A. Bonsor

The stylonurid eurypterid Leiopterella tetliei Lamsdell, Braddy, Loeffler, and Dineley, 2010 (Chelicerata: Eurypterida: Rhenopteridae) from the Early Devonian (Lochkovian) of Nunavut in Arctic Canada is redescribed. Restudy of the holotype under polarized light revealed a labrum, epistomal sutures, prosomal appendage III, and deltoid plates anterior to the genital appendage. An additional new specimen preserves the distal podomeres of appendage VI and gradually tapering opisthosomal tergites. The characters resolved here support the hypothesis that L. tetliei was relatively basal within the wider Stylonurina clade, with its tapering postabdomen supporting a more basal position within Rhenopteridae than previously suggested.

Devonian

Appendage

10.1139/cjes-2021-0015

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Citations (1)

Supplementary results from Dinosaur diversification rates were not in decline prior to the K-Pg boundary

Figshare (2020)

Joseph A. Bonsor Paul M. Barrett Thomas J. Raven Natalie Cooper

Large data tables containing all the results of the mcmcglmm models

10.6084/m9.figshare.13240908

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Citations (0)

Relative skull size evolution in Mesozoic archosauromorphs: potential drivers and morphological uniqueness of erythrosuchid archosauriforms

Palaeontology (2022)

Jordan Bestwick Pedro L. Godoy Susannah C. R. Maidment Martín D. Ezcurra Mia Wroe

Abstract Little is known about the large‐scale evolutionary patterns of skull size relative to body size, and the possible drivers behind these patterns, in Archosauromorpha. For example, the large skulls of erythrosuchids, a group of non‐archosaurian archosauromorphs from the Early and Middle Triassic, and of theropod dinosaurs are regarded as convergent adaptations for hypercarnivory. However, few investigations have explicitly tested whether erythrosuchid and theropod skulls are indeed disproportionately large for their body size, and whether this trend is driven by hypercarnivory. Here, we investigate archosauromorph relative skull size evolution, examining the scaling relationships between skull and body size of Palaeozoic and Mesozoic archosauromorphs using a robust phylogenetic framework and assessing the influence of potential drivers, such as taxonomy, diet, locomotory mode and inhabited biotope. Our results show that archosauromorph relative skull sizes are largely determined by phylogeny and that the other drivers have much weaker levels of influence. We find negative allometric scaling of skull size with respect to body size when all studied archosauromorphs are analysed. Within specific groups, skull size scales with positive allometry in non‐archosaurian archosauromorphs and, interestingly, scales isometrically in theropods. Ancestral reconstructions of skull–femur size ratio reveal a disproportionately large skull at the base of Erythrosuchidae and proportionately sized skulls at the bases of Theropoda, Carnosauria and Tyrannosauroidea. Relative skull sizes of erythrosuchids and theropods are therefore distinct from each other, indicating that disproportionately large skulls are not a prerequisite for hypercarnivory in archosauromorphs, and that erythrosuchids exhibit a bauplan unique among terrestrial Mesozoic carnivores.

Allometry

10.1111/pala.12599

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Citations (8)

OSTEOLOGY AND RELATIONSHIPS OF CUMNORIA PRESTWICHII (ORNITHISCHIA: ORNITHOPODA) FROM THE LATE JURASSIC OF OXFORDSHIRE, UK

Monographs of the Palaeontographical Society (2022)

Susannah C. R. Maidment Kimberley E. J. Chapelle Joseph A. Bonsor David J. Button Paul M. Barrett

The iguanodontian dinosaurs have a fossil record that extends from the Middle Jurassic to the end of the Cretaceous, by which time they had diversified to become the dominant herbivores of Laurasian ecosystems. They are historically important because fossils of British iguanodontians were among the first to be recognised as the gigantic reptiles that formed the basis for naming Dinosauria. However, the early stages of their evolution remain obscure because of a sparse fossil record, and taxonomic and systematic controversies among non-hadrosaurid iguanodontians abound. In order to shed light on the early stages of iguanodontian evolution, new discoveries and re-interpretations of historic specimens are crucial. Here, we redescribe the Late Jurassic early-branching iguanodontian Cumnoria prestwichii from the Kimmeridge Clay Formation of Oxfordshire, UK, and assess its phylogenetic position. We find that Cumnoria is distinct from the North American taxon Camptosaurus, with which it was previously synonymized, and is valid, possessing two autapomorphies of the pectoral girdle. We recover its phylogenetic position as a non-ankylopollexian iguanodontian. Cumnoria represents one of just four valid ornithopod taxa from the Jurassic of Europe.

Autapomorphy

Osteology

Fossil Record

10.1080/02693445.2022.2162669

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Citations (5)