Patterns of diversification in terrestrial vertebrate evolution

保存了复杂骨骼和牙齿的脊椎动物化石记录，为研究导致现代生态系统形成的机制和条件，提供了跨越大时间尺度的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了地球历史上一个伟大篇章的开始，即脊椎动物对陆地的征服。在3.11亿年前它们首次出现的600万年里，我们看到了一直延伸到现在的快速进化辐射，包括现存的鳞片动物、海龟、鳄鱼、鸟类、哺乳动物和许多灭绝的亲戚，包括恐龙。正在进行的脊椎动物古生物学研究，包括解剖学、分类多样性和早期羊膜动物的系统发育关系，将继续成为本提案的一部分，因为新的发现可能对我们对脊椎动物进化的理解产生重大影响。在这里，我建议将这些正在进行的调查与生态多样性的研究结合起来。因此，我计划评估分类和生态多样性随时间的进化变化，这反映在它们重建的摄食行为上。首先，我将首次整合跨进化枝的校准系统发育分析，以便更好地理解群落内的多样化和进化模式。然后，我将研究形态变化（差异），包括牙齿和下颌在比较、系统发育和时间背景下的多样性，以追踪早期羊膜动物在进化过程中获取以前无人居住的生态空间和新的食物资源时的生态多样性。在连续的古生代群落中，牙颌形状和大小变化的形态测量分析将被组织成8个时间箱，从晚石炭世（311 Ma）到中二叠世（272 Ma）。为了了解这些古生代群落中存在的生态多样性，我计划量化牙齿和颌骨形态的变化，并推断每个分类单元的饮食偏好。其他几个变量，包括颅和颅后数据可能包括在总差异分析中。由于现存的爬行动物在形态上与古生代陆地羊膜动物相似，鳞片动物可以作为现存的模式系统。我的研究小组将首次开发可应用于早期羊膜动物的生态形态学模型，并测试饮食变化对羊膜动物生态多样化的假设重要性。结合生态和分类多样性模式的新应用代表了我们处理这一古生物研究项目的变革方式之一。这些分析将为陆生脊椎动物进化初期早期羊膜动物的群落结构和进化提供新的线索。***** * 0* 0

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 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. Within 6*million years of their first appearance*311 Million year ago (Ma), we see rapid evolutionary radiations that extend to*the present, and include extant squamates, turtles, crocodiles,*birds, mammals, and many extinct relatives, including dinosaurs.***Ongoing research in vertebrate paleontology including the anatomy,*taxic diversity, and phylogenetic relationships of early amniotes will continue*to be part of the present proposal because new discoveries can have major*impacts on our understanding of vertebrate evolution. Here I propose to combine*these ongoing investigations with studies of ecological diversity. I therefore*plan to evaluate evolutionary changes in both taxic and ecological diversity*through time as reflected by their reconstructed feeding behaviour. First, I*will integrate for the first time calibrated phylogenetic analyses across*clades for a better understanding of patterns of diversification and evolution*within communities. I will then 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 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 8 time bins that*extend from the Late Carboniferous (311 Ma) to the Middle Permian (272 Ma). In*order to understand the ecological diversity present in these Paleozoic*communities I plan to quantify variation in tooth and jaw morphology, and*deduce the dietary preferences in each taxon. Several other variables,*including cranial and postcranial data may be included in the total disparity*analyses. Since extant reptiles show morphological similarities to Paleozoic*terrestrial amniotes, squamates can be used as extant model systems. My*research group will develop for the first time ecomorphological models that can*be applied to early amniotes, and test the hypothetical importance of dietary*shifts in the ecological diversification of amniotes. The novel use of combined ecological*and taxic diversity patterns represents one of the transformative ways in which*we approach this paleobiological research program. These analyses will shed new light on the community structure and evolution of early amniotes during the*initial stages of terrestrial vertebrate evolution.***** * 0* 0