Locomotor Constraints and Innovations in Primitive Mammals

原始哺乳动物的运动限制和创新

• 批准号: 0520100
• 负责人: Stephen Reilly
• 金额: $ 36.32万
• 依托单位: Ohio University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0520100&HistoricalAwards=false
• 关键词: Locomotor; Constraints; Innovations; Primitive; Mammals

Locomotor Constraints and Innovations in Primitive MammalsStephen M. ReillyOhio UniversityThe proposed research will examine the locomotor system in marsupial and placental mammals in which different constraints and innovations appear to have molded the evolution of locomotor design, gaits and the use of mechanical energy-saving systems. Integrated studies of anatomy, gait, limb and axial movements, muscle activity patterns, ground reaction forces and whole-body mechanics will compare locomotor dynamics in two important examples of evolutionary transitions of vertebrate locomotion: from the primitive tetrapod condition to early mammalian forms and between marsupials and placental mammals. The work will follow up on discoveries from previous NSF support showing that the "epipubic" bones lying in the belly wall in front of the pelvis and associated abdominal muscles function in a "cross-couplet system" controlling trunk bending and footfall patterns during locomotion. The research will test the hypotheses that 1) this system, characteristic of primitive mammals, constrains generalized marsupials to trotting gaits and bouncing mechanics, and 2) release from this morphological constraint in some marsupials and placental mammals (via the loss of the epipubic bones) allows the use of an expanded range of gaits and energy-saving mechanisms in locomotion. The specific aim is to quantify abdominal wall function and locomotor dynamics in a range of marsupials and primitive placental mammals to better understand the epipubic bone function, its constraints on locomotor dynamics and the consequences of epipubic bone loss.The advent of the cross-couplet system and its subsequent retention in all basal mammalian taxa reveals a significant and as yet unrecognized critical innovation in the transition from generalized amniote to mammalian patterns of locomotion. Appearing concomitantly with the key mammalian traits of endothermy, mastication and lactation, the cross-couplet system is hypothesized to have been a key locomotor innovation leading to the early radiation of mammals. Although it remains a viable locomotor system in many primitive mammals, the subsequent reduction or loss of the epipubic bones, as well as the loss of the cross-couplet system and its constraints, appears to have freed some marsupials and the extant eutherians from the locomotor constraints on gait and mechanics predicted for cross-couplet system. Understanding the locomotor consequences of the appearance and subsequent loss of the epipubic bones is therefore of great significance in mammalian evolution. Quantifying the functional consequences of changes in early mammalian belly design is critical to understanding the radiation of locomotor abilities in higher mammals. The proposed study is novel in relating morphology and kinematics to gaits and mechanics, and this approach bridges the realms of functional morphology and biomechanics to understand some of the deeper causes of variation in animal behavior and will add greatly to our understanding of quadrupedal locomotion.This work provides opportunities for colleagues, from Appalachian high school students to foreign collaborators, to gain hands-on expertise in state-of-the-art techniques spanning the disciplines of functional morphology, biomechanics, ecology and behavior, and to share in the discovery of new insights in science. Integrating anatomy and mechanics (not well understood by the public) with animal behavior (inherently visible to the public) has proven to provide valuable ways to illustrate to society the relationships between research and discovery, and the critical role of anatomical variation and physics in organismal design, function and evolution.

原始哺乳动物的运动限制和创新俄亥俄大学拟议的研究将检查有袋类和胎盘哺乳动物的运动系统，在这些系统中，不同的限制和创新似乎塑造了运动设计、步态和机械节能系统的使用的演变。对解剖学、步态、肢体和轴向运动、肌肉活动模式、地面反作用力和全身力学的综合研究将比较脊椎动物运动进化的两个重要例子的运动动力学：从原始的四足动物状态到早期哺乳动物形式，以及有袋类和胎盘哺乳动物之间的运动动力学。这项工作将跟进之前NSF支持的发现，显示位于骨盆前面腹壁的“耻骨”骨骼和相关的腹部肌肉在一个“交叉联结系统”中发挥作用，控制着躯干的弯曲和移动时的脚步模式。这项研究将检验以下假设：1)这一原始哺乳动物的特征系统，限制了一般有袋类动物的小跑步态和弹跳机制，以及2)一些有袋类动物和胎盘哺乳动物从这种形态约束中解脱出来(通过失去耻骨)允许在运动中使用更广泛的步态和节能机制。其具体目的是量化一系列有袋类和原始胎盘哺乳动物的腹壁功能和运动动力学，以更好地了解耻骨上骨功能、其对运动动力学的限制以及耻骨上骨丢失的后果。交叉联体系统的出现及其随后在所有基础哺乳动物类群中的保留揭示了从广义羊膜动物到哺乳动物运动模式转变的一个重大且尚未被认识的关键创新。与哺乳动物的吸热、咀嚼和哺乳等关键特征一起出现的交叉偶联系统被认为是导致哺乳动物早期辐射的关键运动创新。虽然它在许多原始哺乳动物中仍然是一个可行的运动系统，但随后耻骨上骨的减少或丢失，以及交叉对联系统及其约束的丧失，似乎已经将一些有袋类动物和现存的真兽类从预测的交叉对联系统对步态和力学的运动限制中解放出来。因此，了解耻骨出现和随后丢失的运动后果在哺乳动物进化中具有重要意义。量化早期哺乳动物腹部设计变化的功能后果对于理解高等哺乳动物运动能力的辐射至关重要。这项拟议的研究在将形态和运动学与步态和力学联系起来方面是新颖的，这种方法在功能形态和生物力学领域之间架起了桥梁，以了解动物行为变化的一些更深层次的原因，并将极大地增加我们对四足动物运动的理解。这项工作为从阿巴拉契亚高中生到外国合作者的同事提供了机会，获得跨越功能形态、生物力学、生态学和行为学学科的最先进技术的实践专业知识，并分享科学上的新见解。事实证明，将解剖学和力学(公众不太了解)与动物行为(公众固有地可见)结合起来，可以向社会说明研究和发现之间的关系，以及解剖变异和物理学在有机体设计、功能和进化中的关键作用。