Anatomically Preserved Middle Miocene Flora at Yakima Canyon, Washington State: Floristic Composition, Evolutionary, and Phytogeographic Significance

华盛顿州亚基马峡谷解剖学上保存的中新世植物区系：植物区系组成、进化和植物地理学意义

• 批准号: 9980388
• 负责人: Kathleen Pigg
• 金额: $ 2.96万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9980388&HistoricalAwards=false
• 关键词: Anatomically; Preserved; Middle; Miocene; Flora

ABSTRACT9980388PiggThe middle Miocene Yakima Canyon flora (15.6 Ma) from central Washington state contains anatomically preserved seed, fruit and vegetative plant remains that are quite rarely preserved in the Neogene of North America. These fossils provide taxonomic, evolutionary and phytogeographic data impossible to obtain from the more commonly preserved Neogene leaf compression floras. Based on morphological and anatomical features, plants can be recognized at varying infrageneric taxonomic levels including: a pine, Pinus foisyi, assignable to Subsection Oocarpae, which includes extant California closed cone pines; an oak, Quercus hiholensis of Section Quercus, with acorn developmental features quite similar to those of modern white oaks; a sweet gum, Liquidambar, similar to several modern species of Section Liquidambar, and, among the filicalean ferns, essentially modern Woodwardia, probably assignable to the modern Virginia chain fern W. virginica, and Osmunda wehrii, which fits within the modern Subgenus Osmunda. These plants represent the time interval when the mixed mesophytic forest reached its maximum geographic distribution and grew during what was possibly the warmest interval in the Neogene. In some cases, they represent the "last stand" of a widespread, diverse temperate flora that today is represented by plants with a disjunct Asian/eastern North American distribution. Further study will document an overview of the first temperate middle Miocene flora to be based on anatomically preserved fossil remains, and the presence of several extinct Miocene genera.

华盛顿州中部中中新世亚基马峡谷植物群(15.6 Ma)含有解剖保存下来的种子、水果和营养植物遗骸，在北美新近纪很少保存。这些化石提供了分类、进化和植物地理数据，这些数据是从保存较普遍的新近纪叶压植物群中无法获得的。根据形态和解剖学特征，可以在不同的属下分类水平上识别植物，包括：可归入Oucpae亚组的松树，包括现存的加州闭合球果松树；栎组的栎树，其橡子发育特征非常类似于现代白栎组；甜口胶，Liquidambar，类似于枫香组的几个现代种；以及，在丝状蕨类植物中，基本上是现代的Woodwardia，可能被归类于现代的弗吉尼亚链蕨植物W.virgiica，以及Osmunda wehrii，它属于现代的Osmunda亚属。这些植物代表了中生混交林达到其最大地理分布的时间间隔，并在可能是新近纪最温暖的时间段生长。在某些情况下，它们代表了广泛的、多样化的温带植物区系的“最后一站”，今天的代表是亚洲/北美东部分布不连续的植物。进一步的研究将以解剖保存的化石遗迹为基础，概述第一个温带中中新世植物群，以及几个已灭绝的中新世属的存在。