11 research outputs found
Prevalence and risk indicators of gingivitis and periodontitis in a Multi-Centre study in North Jordan: a cross sectional study
Premaxillary crest variation within the Wukongopteridae (Reptilia, Pterosauria) and comments on cranial structures in pterosaurs
Frequency of periodontal pathogens and Helicobacter pylori in the mouths and stomachs of obese individuals submitted to bariatric surgery: a cross-sectional study
Relationship between periodontal disease and cardiovascular risk factors among young and middle-aged Brazilians. Cross-sectional study
Associations of Periodontal Damage and Tooth Loss with Atherogenic Factors among Patients with Type 2 Diabetes Mellitus
On the Ancestry of Feathers in Mesozoic Dinosaurs
Over the last two decades, the dinosaur fossil record has revealed much about the nature of their epidermal structures. These data challenged long-standing hypotheses of widespread reptile-like scalation in dinosaurs and provided additional evidence that supported the deeply nested position of birds within the clade. Moreover, in recent years, the discovery of filamentous structures in numerous species across the dinosaurian evolutionary tree suggests a model of deep feather homology within dinosaurs, with the appearance of feathers hypothesised to coincide with the dinosaur origin. Thanks to phylogenetic comparative methods, these homologies can now be tested empirically and form the basis of this study. Based on a dataset of 77 dinosaur species that preserve integumentary structures, we undertake a series of model-fitting and ancestral state reconstruction analyses to interpret the evolutionary history and ancestral integumentary condition in dinosaurs. Our results provide the first empirical support for the evolution of feathers in an ordered fashion, but reveal that these evolutionary trends were not always towards ‘more complex’ conditions. Ancestral state reconstructions demonstrate that irrespective of the preferred phylogenetic framework, the ancestral pterosaur condition or whether any one major dinosaur lineage had a Late Triassic-feathered representative, support values for a filamentous/feathered dinosaur ancestor are low. More examples of feathered taxa from across the dinosaur tree, and in particular the discovery of as yet unknown feathered Triassic taxa, will be needed in order to overturn current support for a scaly dinosaurian ancestor