Dissertation Research: Origin of the modern avian locomotor system across a neglected evolutionary interval: insight from new methods and new fossils

论文研究：跨越被忽视的进化区间的现代鸟类运动系统的起源：新方法和新化石的见解

• 批准号: 1500798
• 负责人: Bhart-Anjan Bhullar
• 金额: $ 2.12万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1500798&HistoricalAwards=false
• 关键词: Dissertation; Research; Origin; modern; avian

Despite the biological novelty of avian flight, little is known about what the most recent common ancestor of birds looked like, nor about how that ancestor flew. Using spectacular new fossil material, sophisticated imaging techniques, and rigorous statistical methods, this research will reconstruct the most likely anatomical and functional attributes of the most recent common ancestor of living birds, bringing us closer to understanding how modern birds and their flying ability came to be. Through museum exhibits, media exposure, and innovative online activities, this project has strong potential to educate both children and adults about evolutionary biology and paleontology.The study will begin with allometric analysis of a comprehensive sampling of fossil taxa. Preliminary results from this analysis (based on 13,000 data points from extant birds) indicate a fundamental allometric division between extant flying and flightless birds. This division, based on the relationship between shoulder joint dimensions and body mass, enables, for the first time, the delineation of well-defined ?flying? and ?flightless? zones for morphology. This novel biomechanical ?test? of powered flying potential can easily be applied to Mesozoic fossils, and preliminary results indicate that the acquisition of a biomechanically favorable shoulder:body mass ratio, enabling powered flight, evolved considerably later in avian evolutionary history than is conventionally assumed. These results set the stage for a novel geometric analysis of Mesozoic stem bird postcrania, which will illustrate when the geometrically modern avian flight apparatus arose, and will shed light on the evolutionary dynamics of this deeply integrated morphological system. Next, the study will focus on the avian crown clade, and will generate the first ever three-dimensional in situ muscle and feather reconstructions of adult extant birds, which will facilitate the robust inference of flight muscle morphology for the most recent ancestor of extant birds. This will form the basis of range-of-motion simulations for the flight apparatus of two pivotal fossil stem birds, validated by data from diverse extant taxa. Together, the project outlined here will rigorously document and mechanically interpret one of the most important functional transitions in vertebrate evolutionary history?the acquisition of modern, powered flying ability in birds.

尽管鸟类飞行在生物学上是新奇的，但人们对鸟类最近的共同祖先是什么样子知之甚少，也不知道他们是如何飞行的。利用惊人的新化石材料、复杂的成像技术和严格的统计方法，这项研究将重建最可能的现存鸟类共同祖先的解剖和功能属性，使我们更接近了解现代鸟类及其飞行能力是如何形成的。通过博物馆展览、媒体曝光和创新的在线活动，该项目具有强大的潜力，可以教育儿童和成人有关进化生物学和古生物学的知识。这项研究将从对化石分类群的全面采样进行异速生长分析开始。这项分析的初步结果（基于现存鸟类的13000个数据点）表明，现存会飞的鸟类和不会飞的鸟类之间存在着基本的异速分化。这种基于肩关节尺寸和身体质量之间关系的划分，第一次能够对“飞行”进行定义明确的描绘。和不会飞的?形态区。这种新颖的生物力学试验？初步结果表明，从生物力学角度来看，有利于动力飞行的肩与体质量比在鸟类进化史上的进化要比传统假设的晚得多。这些结果为对中生代干鸟后颅骨进行新的几何分析奠定了基础，这将说明几何现代鸟类飞行装置的出现时间，并将揭示这一深度整合形态系统的进化动力学。接下来，研究将集中在鸟类冠枝上，并将首次生成现存成年鸟类的三维原位肌肉和羽毛重建，这将有助于对现存鸟类最近祖先的飞行肌肉形态进行强有力的推断。这将形成两个关键化石干鸟飞行装置的运动范围模拟的基础，并通过来自不同现存分类群的数据进行验证。总之，这里概述的项目将严格地记录和机械地解释脊椎动物进化史上最重要的功能转变之一。鸟类获得现代动力飞行能力