NSF Postdoctoral Fellowship in Biology FY 2020: Integrating the fossil record with developmental biology to investigate the origin of the avian body plan

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This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Research Using Biological Collections. The fellowship supports research and training of the fellow that will use biological collections in innovative ways. Fossils directly record major changes in animal evolution that would otherwise be lost to time. These changes can be traced back to processes occurring while the animal is still a developing embryo. Therefore, integrating data from both embryos and fossils is critical to understanding how evolution generates new animal forms. This project will integrate the excellent fossil record of the dinosaur-to-bird transition with new developmental techniques to image modern-day bird embryos in high resolution in three dimensions, focusing on the bird pelvis (hips). The fellow’s preliminary data strongly suggest that the pelvis of early-stage bird embryos has the same anatomy as the dinosaurian ancestors of birds. The transition from a dinosaur-like pelvis to a bird pelvis can be seen across 2 days of bird development, showing the striking evolutionary developmental mechanism that formed the anatomy of modern birds. This project will integrate 3D models of both fossils and embryos to confirm this initial finding, illuminating one of the major evolutionary transitions in the history of life. This project will also allow for the training of students from underrepresented groups, leveraging the charisma of the study animals to find broad appeal. The fellow hypothesizes that the early stages of avian pelvic development resemble ancestral dinosaurian states (a process called terminal addition), and that the changes undergone by the avian pelvis during embryonic development may mirror evolutionary history. Preliminary data strongly suggest that the pelvis of early-stage bird embryos retains ancestral dinosaurian states and transitions to the classic ‘avian’ anatomy in later developmental stages. The fellow will integrate data from biomedical imaging (micro-computed tomography [micro-CT]) of fossils/skeletons housed in museum collections with data from novel embryological techniques used to describe three-dimensional embryonic tissues at stages earlier than has been previously possible. This will allow the evolutionary sequence recorded in the fossils and the developmental sequence known from avian embryos to be compared qualitatively and quantitatively (with 3D geometric morphometrics). The fellow will then use the development of ‘soft’ (non-skeletal) tissues to reconstruct the evolution of muscles and nerves during the transition from non-avian theropod dinosaurs to birds. This will illuminate one of the most iconic transformations in vertebrate history by using new embryological methodologies grounded in natural history collections. To broaden the impact of the work, the fellow will train students from underrepresented groups in research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.