Despite advances in knowledge of brain function, the relationship between brain evolution and ecological diversity remains poorly known. A prominent example is that of birds. Taking to the air enabled the dinosaurian ancestors of birds to exploit a range of ecological niches that now underlie the remarkable modern diversity of the group (approximately 10,000 living species). A significant part of this evolutionary success may have stemmed from the development of a relatively large brain, which has been considered necessary for coordinating the various, nuanced components of powered flight. This study complements the NSF BRAIN initiative by using a cross-disciplinary approach to understand the complex neurological evolution of birds and their dinosaurian relatives. To that end, an array of new techniques and new applications of existing technologies are employed to document the major changes in the brain associated with the origin of powered flight. This study also will establish a model of brain expansion complementing that already available for mammals. The outcome will be an unprecedented database of avian brain anatomy that includes not only imagery of morphological systems but also their relation to data generated through brain function.
The relationship between neuroanatomical, cognitive and behavioral evolution remains poorly understood, especially in deep time and across the vertebrate tree of life. This study addresses this relationship using a cross-disciplinary investigation of the evolutionary link between the large brain of living birds and the morphological changes that mark the transition from cursorial (running) dinosaur to flying bird. Initial steps use innovative imaging methods and novel staining techniques to generate the first data on what areas of the brain birds use while flying, and how this activity differs from that of other behaviors. These data will serve as a framework for a broad analysis of encephalization (increasing head size) within living birds and along the lineage where avian flight originated. Shared landmarks will be used to subdivide the endocranial cavity into functionally relevant partitions that allow testing for volumetric size changes between individual neural structures, including those most active during flight. This study also will use geometric morphometrics (anatomical comparisons) to assess covariation between neuroanatomical partitions and thus the presence of functionally and/or evolutionarily integrated regions of the brain. In short, the proposed study will generate data on how birds use their brain and apply those data to better understand the ancient relationship between brain evolution and the origin of the highly derived avian body plan.
