Evolutionary Dissection of the Neck Musculoskeletal System in Dinosaurs

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In contrast to the clawed forelimbs of their dinosaurian ancestors, the highly specialized forelimbs of birds are exclusively adapted for flight which constrains their functional versatility. It is assumed that consequently the avian neck became the functional equivalent to an arm and great divergence is evident in number, form and function of the cervical vertebrae. Owing to methodological advances such as imaging techniques and computer technology, we only recently started deciphering the complex biomechanical adaptations of the neck in birds and the results serve as basis for bioinspired design including an arm for robots. The classic avian body plan was pieced together gradually over tens of millions of years of evolution rather than in one burst of innovation. Traits such as feathers, the furcula, and wings first evolved in the dinosaurian ancestors of birds, whereas other traits such as the pygostyle and a keeled sternum evolved in more derived birds during the Cretaceous. This raises the question of when and how has the highly versatile avian neck evolved? The EDDI team will address this issue by investigating the evolutionary mechanisms responsible for the diversification of the neck in archosaurs, the group of fossil and extinct vertebrates that includes dinosaurs, birds, and crocodilians. To do so, homologies of the skeletal and muscular system of the neck will be established using developmental and morphological data. This will serve as basis for the investigation of changes in the musculoskeletal system of the neck across phylogenetically diverse living and fossil taxa. Reconstructing these patterns among dinosaurs will provide new insights into how evolution drove major morphofunctional changes that underpinned their spectacular evolutionary success, in particular that of their avian descendants. This research will define a new paradigm for inferring patterns of the interconnected evolution of bone and muscle from the fossil record.