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Title: Skull form and function in therizinosaur dinosaurs
Author: Lautenschlager, Stephan
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Maniraptoriformes, the speciose group of derived theropod dinosaurs that ultimately gave rise to modern birds, display a diverse and remarkable suite of skeletal adaptations. Apart from the evolution of flight, a large-scale change in dietary behavior appears to have been one of the main triggers for adaptations in the bauplan of these derived theropods. Amongst the different skeletal specialisations, partial or even complete edentulism and the development of keratinous beaks form a recurring and persistent trend in the transition from derived nonavian dinosaurs to birds. Therizinosauria is one of the most enigmatic and peculiar clades among Maniraptoriformes, exhibiting an unusual suite of characters, such as lanceolate teeth, a rostral rhamphotheca, long manual claws and a wide, opisthopubic pelvis. This specialised anatomy has been associated with a shift in dietary preferences and an adaptation to herbivory, making therizinosaurs prime candidates to assess the functional significance of these morphological characters. Centered on the skull of the therizinosaur Erlikosaurus andrewsi from the Upper Cretaceous of Mongolia, a wide range of computational techniques (including computed tomography, digital reconstruction and biomechanical modelling using finite element analysis) has been utilised in this thesis to investigate the skull form and function in therizinosaurs and to elucidate their palaeobiology. Evidence from hard- and soft tissue reconstructions of Erlilcosaurus andrewsi demonstrate that teeth had lost their importance and function in derived therizinosaurs. Rather a keratinous rhamphotheca was developed early in Therizinosauria to replace rostral teeth as a main device to procure and manipulate food. The results of a highly detailed biomechanical model of Erlikosaurus andrewsi further suggest that a keratinous rhamphotheca represent an evolutionary innovation developed early in the transition from non-avian dinosaurs to birds to enhance cranial stability, distinct to postulated mass-saving benefits associated with the origin of flight.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available