Patterns of diversification in terrestrial vertebrate evolution

脊椎动物的化石记录保存了复杂的骨骼和牙齿，为研究导致现存陆地群落和现代生态系统的机制和条件提供了大时间尺度上进化动力学的最佳证据。羊膜动物进化的起源和最初阶段代表着地球历史上一个伟大篇章的开始--脊椎动物征服陆地。特别是，在3.16亿年前首次出现后不久，我们看到爬行动物和突触体在晚石炭世和早二叠世的快速进化辐射。这一时期对于陆地脊椎动物进化的研究尤其重要，因为此时开始的进化创新形成了现存群落及其鳞类、龟类、鳄鱼、鸟类和哺乳动物成员的基础，以及以恐龙等爬行动物为主的中生代群落的基础。同样，一些两栖动物分支在古生代经历了快速和持续的多样化，因为它们进化成完全陆地的生活方式。在这一背景下，失足类动物具有重要意义和研究价值，因为它们在产生利萨姆比目动物(现存的两栖动物--青蛙、火蜥蜴和足类)之前，作为陆地捕食者与羊类共存。 对古生代陆生四足动物的解剖学、多样性和进化关系的长期研究将继续是这一提议的一部分，因为新的发现对我们理解脊椎动物的进化具有重大影响。在这项提议中，我将采取双管齐下的方法。首先，我将扩展我最近在牙齿解剖、发育和替换方面的工作，并建议在系统发育框架内评估重建的摄食行为所反映的出租车和生态多样性的变化。我将研究形态变异(差异)，包括在比较的系统发育和时间背景下的牙齿和下颌的多样性，以跟踪早期羊膜动物和同时代陆地四足动物的生态多样性，因为它们进化到获得以前未被占领的生态空间和新的食物资源。对连续的古生代群落中牙齿和颌骨形状和大小变化的形态计量学分析将被组织成从晚石炭世(316 Ma)到早二叠世末(272 Ma)的时间段。其次，这种新的方法将与其他骨骼变量，特别是来自多模式CT数据的新的脑颅解剖学结合到全面的时间校准的系统发育分析中。在系统发育框架内新颖地使用生态和分类多样性模式，代表了我们接近脊椎动物进化这一重要篇章的变革性方法之一。这些分析将首次揭示陆生脊椎动物进化初期四足动物的群落结构和进化。

The fossil record of vertebrates, with preservation of complex skeletons and teeth provides the best evidence of evolutionary dynamics across large temporal scales for investigating the mechanisms and conditions that led to the extant terrestrial communities, and modern ecosystems. The origin and initial stages of amniote evolution represent the start of a great chapter in earth's history, the conquest of land by vertebrates. In particular, shortly after their first appearance 316 Million years ago, we see rapid evolutionary radiations of reptiles and synapsids during the Late Carboniferous and early Permian. This time period is particularly important for studies of vertebrate evolution on land because evolutionary innovations initiated at this time form the foundations of extant communities and their squamate, chelonian, crocodilian, avian, and mammalian members, as well as those of Mesozoic communities dominated by reptiles like dinosaurs. Similarly, some clades of amphibians underwent rapid and sustained diversification during the Paleozoic as they evolved to a fully terrestrial lifestyle. Dissorophoids are significant and research worthy within this context because they coexisted with amniotes as terrestrial predators before giving rise to lissamphibians (extant amphibians - frogs, salamanders, and apodans). Long term studies of the anatomy, diversity, and evolutionary relationships of Paleozoic terrestrial tetrapods will continue to be part of this proposal because new discoveries have major impacts on our understanding of vertebrate evolution. In this proposal I will take a two-pronged approach. Firstly, I will expand my recent work on dental anatomy, development and replacement and propose to evaluate changes in both taxic and ecological diversity within a phylogenetic framework as reflected by the reconstructed feeding behaviour. I will examine morphological variation (disparity), including dental and mandibular diversity in comparative phylogenetic and temporal contexts in order to track the ecological diversification of early amniotes and coeval terrestrial tetrapods as they evolved to access formerly unoccupied ecospaces and novel food resources. Morphometric analyses of variation in tooth and jaw shape and size in successive Paleozoic communities will be organized into time bins that extend from the late Carboniferous (316 Ma) to the end of the early Permian (272 Ma). Secondly, this new approach will be incorporated with other skeletal variables, especially new neurocranial anatomy derived from multimodal CT data into comprehensive time calibrated phylogenetic analyses. The novel use of ecological and taxic diversity patterns within a phylogenetic framework represents one of the transformative ways in which we approach this important chapter in vertebrate evolution. These analyses will shed light for the first time on the community structure and evolution of tetrapods during the initial stages of terrestrial vertebrate evolution.