Collaborative Research: Integrated Study of an Exceptional Avifauna from the Eocene Green River Formation: New Data on Avian Evolution and Taphonomy

所有活着的鸟类出现的模式和时间仍然是脊椎动物系统学中一些最有争议的问题。鸟类化石越来越多地被用作分子分歧测年的校准点，并被用来检验宏观进化假说。该项目将对北美保存最完好的早古近纪鸟类组合进行研究，以快速推进我们对新生代鸟类进化和分类的理解。该组合包含丰富的化石样本，这些化石在不到2000年的时间里沉积在单个湖泊的不同的、绘制的和沉积特征的亚环境中，保存得非常完好，但基本上没有特征。这些矿床的年龄为50.2-1.9 Mya，产于怀俄明州的化石巴特成员中。该项目是第一个整合系统分析和对保护偏见的调查，这些偏见影响了关键湖泊组合的化石证据。这些结果对于获得：1)早期古近纪鸟类生物多样性的全球视角；2)了解鸟类辐射的时间和古生物地理模式；以及3)回答如何在关键的湖泊环境中保存鸟类及其羽毛的基本问题是至关重要的。这一结果将具有更广泛的意义，为比较和表明在类似环境中保存的其他鸟类化石组合可能存在的偏见提供基础，例如产生羽毛恐龙的早白垩世热河群。发现在这类沉积物中可能系统性地缺失了哪些类别的分类群的唯一方法是通过这里提出的方法：在可能的最佳条件下对鸟类多样性最完整的快照之一进行系统发育和攻击学研究。该项目的更广泛影响包括以标本为基础的解剖学、系统方法论和克隆学方法的新颖整合；博士后、博士和本科生培训；以及通过博物馆展品、相关的外展材料和讲座促进公众对进化和生物多样性的理解。

The pattern and timing of the emergence of all living birds remain some of the most contentious questions in vertebrate systematics. Avian fossils are increasingly sought as calibration points for molecular divergence dating and used to test macroevolutionary hypotheses. This project will investigate the best-preserved early Paleogene avian assemblage from North America to forward rapidly our understanding of Cenozoic avian evolution and taphonomy. The assemblage comprises a rich sample of exceptionally preserved, but largely uncharacterized, fossils deposited in less than ~2000 years in distinct, mapped, and sedimentologically characterized sub-environments of a single lake. The deposits are tightly dated to 50.2+-1.9 Mya and occur in the Fossil Butte Member in Wyoming. The project is the first to integrate systematic analyses and an investigation of preservational biases that impact fossil evidence from key lake assemblages. The results are essential to gaining: 1) a global perspective on early Paleogene avian biodiversity; 2) an understanding of the timing and paleobiogeographic patterns of the avian radiation; and 3) answers to fundamental questions of how birds and their feathers are preserved in key lacustrine environments. The results will have wider significance in providing a basis for comparison and indication of likely biases in other assemblages of fossil birds preserved in similar settings such as the Early Cretaceous Jehol Group that yields feathered dinosaurs. The only way to discover what categories of taxa may be systematically missing in such deposits is through the approach proposed here: phylogenetic and taphonomic study of one of the most complete 'snap shots' of avian diversity under the best conditions possible. The broader impacts of the project include novel integration of specimen-based teaching of anatomy, systematic methodologies, and taphonomic approaches; postdoctoral, doctoral and undergraduate training; and the promotion of public understanding of evolution and biodiversity via museum exhibits, linked outreach materials, and lectures.