Systematics of the Early Oligocene Bridge Creek Flora, Oregon, and Implications for the Derivation and Expansion ofBroadleaved Deciduous Forests in the Northern Hemisphere

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The John Day Formation of Oregon contains ancient lake sediments (30 to 35 million years old) in which plant remains are well preserved. Leaves, fruits, seeds, pollen, and even flowers have been recovered by paleobotanists, and these have been interpreted as one of the earliest cool temperate forests in the mid-latitudes of the Northern Hemisphere. This marks a shift toward cooler climates, and for this reason Dr. Steven Manchester proposes careful taxonomic revision of the plant remains collectively known as the Bridge Creek Flora. Detailed study of their anatomy will form the basis of accurate identifications. This taxonomic revision will be followed by comparisons with European floras of similar age, and analysis of evolutionary relationships with earlier species from different altitudinal habitats. The proposed research will find an eager audience among paleocologists, paleoclimatologists, stratigraphers, phytogeographers, and evolutionary biologists in general. The ways in which organisms respond to global climate change is particularly timely, and the fossil plants that are targeted for study represent a "natural experiment" that occurred tens of millions of years ago. A detailed and accurate recognition of different plant species is essential for a correct interpretation of this experiment's results.