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

俄勒冈州的约翰戴组含有一个古老的湖泊 沉积物（3000万至3500万年）中的植物遗骸， 保存完好。 叶子，果实，种子，花粉，甚至花 都被古植物学家发现了 被认为是世界上最早的冷温带森林之一， 北方半球中纬度地区。 这标志着一个转变 更凉爽的气候，因此，史蒂芬曼彻斯特博士 建议对植物遗骸进行仔细的分类修订， 统称为桥溪植物群。 详细研究 它们的解剖结构将构成准确识别的基础。 这一分类学修订之后将与 相似时代的欧洲植物区系及其演化分析 与不同海拔的早期种的关系 栖息地 这项拟议中的研究将在以下人群中找到一个热切的听众： 古生物学家，古气候学家，地层学家 植物地理学家和进化生物学家 的 生物对全球气候变化的反应方式 特别及时，和化石植物的目标， 研究代表了一个“自然实验”， 几百万年前 详细而准确地认识到 不同的植物种类是正确解释的必要条件 这个实验的结果。

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.