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

所有现存鸟类出现的模式和时间仍然是脊椎动物系统学中最有争议的问题之一。鸟类化石越来越多地被用作分子分歧定年的校准点，并用于测试宏观进化假说。 本项目将对北美保存最完好的古近纪早期鸟类组合进行研究，以快速推进我们对新生代鸟类演化和埋藏学的认识。该组合包括一个丰富的样本异常保存，但很大程度上是uncharacterized，化石沉积在不到2000年的独特的，映射，和沉积学特征的子环境的一个单一的湖泊。这些矿床的年代确定为距今50.2+-1.9百万年，产于怀俄明州的化石丘段。该项目是第一个将系统分析和对影响关键湖泊组合化石证据的解释性偏见的调查相结合的项目。这些结果对于获得以下信息至关重要：1）对古近纪早期鸟类生物多样性的全球视角; 2）对鸟类辐射的时间和古生物地理模式的理解; 3）对鸟类及其羽毛如何在关键湖泊环境中保存的基本问题的答案。这些结果将具有更广泛的意义，为比较和指示在类似环境中保存的其他化石鸟类组合（如早白垩世热河群）中可能存在的偏差提供基础。发现什么类别的分类群可能是系统性失踪，在这样的存款的唯一途径是通过这里提出的方法：系统发育和埋藏研究的最完整的“快照”的鸟类多样性在最好的条件下。该项目的更广泛的影响包括新的整合，基于解剖学的教学，系统的方法和埋藏学方法;博士后，博士和本科生培训;并通过博物馆展览，链接的宣传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.