DISSERTATION RESEARCH: Extinction and Diversification Dynamics of Archosauria Through Early Mesozoic Climate Crises

论文研究：早期中生代气候危机中主龙类的灭绝和多样化动态

• 批准号: 1501489
• 负责人: James Clark
• 金额: $ 1.92万
• 依托单位: George Washington 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: 2015-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1501489&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Extinction; Diversification; Dynamics

Two mass extinctions occurred early in the Mesozoic Era shortly after dinosaurs appeared, and multiple lines of evidence suggest that dramatic global climate change events were contributing factors. This project will investigate the response of the extinct relatives of birds and crocodilians (the Archosauria) to these episodes. The primary objectives of this study are to analyze the evolutionary relationships of fossil archosaurs, and use these evolutionary relationships as a framework to investigate how archosaur respiratory anatomy and body temperature regulation changed after the extinctions at the end of the Triassic Period and during the Early Jurassic Epoch. The study will test the hypothesis that global warming events initiated evolutionary changes in respiratory anatomy and contributed to currently unexplained patterns of extinction and diversification of extinct archosaurs, including dinosaurs. This research will provide insight into the ways that vertebrate communities on land respond to rapid changes in climate, and may help to predict which species will experience an increased risk of extinction during modern climate change. This research will provide multiple opportunities for undergraduate training. In addition, educational materials based on the results will be distributed to educators at secondary and higher education levels, as well as disseminated in the form of scientific papers and presentations at professional meetings.Time-calibrated phylogenies of Archosauria will be estimated using both parsimony analyses of morphology and combined-evidence Bayesian approaches to phylogeny reconstruction incorporating molecular sequence data from extant archosaurs. Character transformation rates for respiratory-related characters (e.g. postcranial skeletal pneumaticity) and non-respiratory characters will be modeled iteratively over a large sample of time-calibrated trees to account for uncertainty in phylogeny and chronology. Non-parametric statistics will be used to test for the presence of rate-shifts in respiratory character evolution surrounding the interval of extinctions and associated climate changes in the early Mesozoic Era.

在恐龙出现后不久，在中生代初期发生了两次大规模灭绝，有多种证据表明，戏剧性的全球气候变化事件是促成因素。该项目将调查鸟类和鳄鱼（Archosauria）对这些事件的灭绝亲戚的反应。这项研究的主要目的是分析化石弓箭手的进化关系，并使用这些进化关系作为框架，以研究弓箭手呼吸解剖结构和体温调节在三叠纪末期以及早期侏罗纪阶段结束时的灭绝后如何变化。该研究将检验以下假设：全球变暖事件引发了呼吸解剖学的进化变化，并导致了当前无法解释的灭绝模式和包括恐龙在内的灭绝弓形虫的多样化。这项研究将提供有关土地上脊椎动物群落应对气候快速变化的方式的洞察力，并可能有助于预测哪些物种将在现代气候变化期间会增加灭绝风险。这项研究将为本科培训提供多种机会。此外，基于结果的教育材料将在中学和高等教育水平上分配给教育者，并以科学论文和专业会议上的科学论文和演讲形式分发。将使用形态学的拟及培训序列序列的分类库中估算出Archosauria的时间发育。呼吸相关特征的特征转换率（例如，颅后骨骼气动性）和非呼吸性特征将在大量的时间校准树样本上迭代建模，以说明系统发育和年表的不确定性。非参数统计量将用于测试围绕中生代早期灭绝和相关气候变化的呼吸道进化中的速率转移的存在。