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

摘要：哺乳动物以其广泛的运动行为而闻名，包括独特的步态，如飞奔和跳跃。这些步态之所以成为可能，是因为脊椎骨被细分为两个不同的区域：胸区，那里有肋骨，帮助呼吸；腰椎区域，没有肋骨，活动能力强，有运动功能。结合起来，这两部分脊椎骨使哺乳动物能够同时呼吸和移动，从而允许长时间使用高速步态。但是，这个关键的哺乳动物特征是如何进化的呢？利用尖端的3D技术，结合丰富的哺乳动物及其祖先的化石记录，这项研究将追踪哺乳动物脊椎骨的起源和进化，以及它与哺乳动物特定运动行为发展的联系。这项工作将加深我们对哺乳动物的一个关键特征的历史的理解，以及对医学有重要意义的部分骨骼。研究的传播将通过两个主要渠道进行。首先，屡获殊荣的YouTube频道“the Brain Scoop”将制作一系列教育在线视频。该系列将包括三集，以有趣和引人入胜的方式记录研究项目的不同阶段，其核心目的是鼓励青少年和年轻人对科学，技术，工程和数学（STEM）主题的兴趣增加。其次，“大脑独家新闻”系列将被用作菲尔德博物馆n.w.哈里斯学习收藏的“体验箱”的基础。这个盒子将供K-12教育工作者在课堂上借用和使用，其中包括与“下一代科学标准”直接相关的每集的复制标本和活动。哺乳动物以其广泛的运动行为而闻名，包括独特的不对称步态，如飞奔和跳跃。不对称步态的形成是由于脊柱背侧（胸带和骨盆带之间的区域）被细分为两个形态和功能上不同的区域。在前面，胸椎区有肋骨，专门用于呼吸，而在后面，背腹侧活动的腰椎区负责运动。结合起来，区域化的背椎骨使哺乳动物能够同时呼吸和移动，允许长时间使用高速步态。但是，这个关键的哺乳动物特征是如何进化的呢？现代物种为研究这个基本的进化问题提供的信息很少，因为它们都有不同的胸椎和腰椎。然而，哺乳动物所属的新孔门拥有丰富的化石记录，为哺乳动物的起源和进化提供了详细的视角。利用尖端的形态计量学、生物力学和3D数字建模技术，该项目采用深度时间方法来研究化石突触类动物脊柱的功能，并追踪胸腰椎区域和背腹侧活动的起源和演变。将采用四种协同方法：1)形态计量学数据将用于检查现代四足动物和化石突触动物脊柱背侧的形态功能区区化程度；2)对现代四足动物的脊柱进行离体弯曲实验，以确定形式和功能之间的联系；3)将对化石突触体脊柱的三维数字模型进行新颖的虚拟弯曲实验，以确定其运动倾向；4)数据将在严格的系统发育背景下合成，以重建胸腰椎区域和背腹侧活动的起源和演化。

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.