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

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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.