Collaborative Research: Functional evolution of the mammalian backbone: insights from the forerunners of mammals

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Revised Title: Collaborative Research: Functional evolution of the mammalian backbone: insights from the forerunners of mammalsNon-technical AbstractMammals are known for their great range of locomotor behaviors, including unique gaits such as galloping and bounding. These gaits are made possible by the subdivision of the backbone into two distinct regions: the thoracic region, which bears ribs and aids in breathing; and the lumbar region, which is ribless, highly mobile and functions in locomotion. Combined, these two sections of the backbone allow mammals to breathe and move simultaneously, permitting the use of high speed gaits for prolonged periods of time. But, how did this key mammalian trait evolve? Using cutting-edge 3D technology, along with the rich fossil record of mammals and their ancestors, this research will trace the origin and evolution of the mammalian backbone and its link with the development of mammal-specific locomotor behaviors. The work will deepen our understanding of the history of a key characteristic of mammals and part of the skeleton that is of great medical importance. Dissemination of the research will occur via two primary outlets. First, a series of educational online videos will be produced by the award-winning YouTube channel "The Brain Scoop". The series will include three episodes documenting different stages of the research project in a fun and engaging way, with the core aim to encourage an increased interest in Science, Technology, Engineering and Mathematics (STEM) topics among teenagers and young adults. Second, the "The Brain Scoop" series will be used as the foundation for an 'Experience Box' in the Field Museum's N. W. Harris Learning Collection. The box will be available for K-12 educators to borrow and use in their classrooms, and will include replica specimens and activities related to each episode that are directly tied to Next Generation Science Standards.Technical AbstractMammals are known for their great range of locomotor behaviors, including unique asymmetric gaits such as galloping and bounding. Asymmetric gaits are made possible by the subdivision of the dorsal vertebral column (the area between the pectoral and pelvic girdles) into two morphologically and functionally distinct regions. Anteriorly, the thoracic region bears ribs and is specialized for respiration, whereas posteriorly the dorsoventrally mobile lumbar region functions in locomotion. Combined, the regionalized dorsal vertebrae allow mammals to breathe and move simultaneously, permitting the use of high speed gaits for prolonged periods of time. But, how did this key mammalian trait evolve? Modern species provide little information for examining this fundamental evolutionary question, as they all possess distinct thoracic and lumbar regions. However, the clade to which mammals belong, Synapsida, has a rich fossil record that provides a detailed view of the origin and evolution of mammals. Using cutting-edge morphometric, biomechanical, and 3D digital modeling techniques, this project takes a deep-time approach to examine function of the vertebral column in fossil synapsids, and to trace the origin and evolution of the thoracolumbar region and dorsoventral mobility. Four synergistic approaches will be utilized: 1) morphometric data will be used to examine the degree of morphofunctional regionalization of the dorsal vertebral column in modern tetrapods and fossil synapsids; 2) ex vivo bending experiments will be conducted on the vertebral columns of modern tetrapods bracketing the synapsid-mammal transition to determine the link between form and function; 3) novel virtual bending experiments will be carried out on 3D digital models of fossil synapsid vertebral columns to determine their propensity for movement; and 4) the data will be synthesized within a strict phylogenetic context to reconstruct the origin and evolution of the thoracolumbar region and dorsoventral mobility.