Collaborative Research: Unearthing Antarctica's role in the Late Cretaceous Evolution of Flowering Plants

第一部分：非技术描述开花植物是当今地球上占主导地位的陆地植物群。它们在气候-生命相互作用中发挥着重要作用，对人类福祉（健康、食物、材料）至关重要。尽管它们对我们很重要，但它们的早期进化仍然是个谜。如果没有这些植物如何进化的地质背景，我们将无法完全理解它们在调节气候和构造环境方面的作用。这一点很重要，因为今天的陆地生态系统正在发生许多变化。化石记录表明，与开花植物早期多样化有关的关键事件发生在白垩纪（1.45 - 6600万年前）。最近发现的这一时期的花和果实化石极大地促进了我们对早期开花植物进化的理解。然而，这些发现大多来自北半球，而南半球的类似发现相对较少。该项目将通过收集和描述来自南极洲西部的晚白垩世开花植物化石，并将其置于进化框架中，以更好地了解早期开花植物的进化、生物地理历史以及南极洲在现代生态系统形成中的作用，来解决这一数据的缺乏问题。据报道，南极洲西部是南半球唯一保存着白垩纪晚期（1 - 6600万年前）三维保存的花朵和水果的地方。因此，这些化石的恢复和研究可以有意义地进一步了解开花植物进化的早期阶段。这项工作将导致对新物种的描述，这些物种将被置于进化分析和生物地理框架中，这将有助于阐明南半球白垩纪开花植物的多样化。这些化石将提供洞见，使我们能够预测哪些植物可能在变暖的南极和世界中茁壮成长。第二部分：技术描述南半球晚白垩世开花植物（被子植物）的多样化尚不清楚，部分原因是具有良好特征的植物生殖结构化石数量有限。古植物学研究表明，南极洲是白垩纪开花植物多样化的重要区域，也是南半球已知的唯一一个含有过矿化的白垩纪晚期被子植物生殖结构的地方。拟议的研究将通过恢复和描述晚白垩世南极被子植物，将它们置于系统发育背景中，并测试在动物身上观察到的北美和冈瓦纳之间的生物地理联系，阐明南极洲在被子植物进化和现代生态系统组装中的作用。实地考察将在南极洲西部的詹姆斯罗斯盆地进行，先前的报告和初步数据表明，那里存在晚白垩纪时期的植物群，包括结构上保存完好的生殖结构。这些化石的特殊保存使我们能够记录必要的数据，从而将它们置于系统发育框架中，从而确定它们的进化和生物地理背景。James Ross盆地内的被子植物生殖结构具有重要的年代和地理意义，对了解南半球被子植物和生态系统的系统发育多样性具有重要意义。收集的化石将使用标准的物理技术和微ct成像进行检查。对这些化石的研究将导致对新物种和可能更高分类群的描述，并为白垩纪时期西南极洲的植物多样性和组成提供一个独特的视角。此外，这些化石将被置于系统发育框架内，这将有助于阐明哪些谱系在南极洲多样化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Part I: Nontechnical DescriptionFlowering plants are the dominant land plant group on Earth today. They play essential roles in climate-life interactions and are fundamental for human well-being (health, food, materials). Despite their importance to us, their early evolution has remained enigmatic. Without the geological context of how these plants evolved, we will not fully understand their roles in regulating climate and structuring environments. This is important as terrestrial ecosystems today are undergoing many changes. The fossil record indicates that critical events relating to the early diversification of flowering plants occurred during the Cretaceous period (145–66 million years ago). Recent discoveries of fossil flowers and fruits from this time period have significantly furthered our understanding of early flowering plant evolution. However, the majority of these discoveries are from the Northern Hemisphere while similar discoveries from the Southern Hemisphere are relatively lacking. This project will address this paucity of data by collecting and describing Late Cretaceous flowering plant fossils from Western Antarctica and placing them in evolutionary frameworks to better understand early flowering plant evolution, biogeographic history, and Antarctica’s role in the formation of modern ecosystems. Western Antarctica is the only place in the Southern Hemisphere that is reported to contain Late Cretaceous-aged (100–66 million years ago) three-dimensionally preserved flowers and fruits. Therefore, the recovery and study of these fossils can meaningfully further our understanding of the early phases of flowering plant evolution. This work will result in the description of new species that will be placed in evolutionary analyses and biogeographic frameworks, which will help clarify the Cretaceous diversification of flowering plants in the Southern Hemisphere. These fossils will provide insights that will allow us to anticipate which plants might thrive in a warming Antarctic and world.Part II: Technical DescriptionThe Late Cretaceous diversification of flowering plants (angiosperms) in the Southern Hemisphere is poorly understood due in part to the limited amount of well-characterized fossil plant reproductive structures. Paleobotanical studies indicate that Antarctica was an important area for the Cretaceous diversification of flowering plants and is the only place in the Southern Hemisphere that is known to contain permineralized Late Cretaceous-aged angiosperm reproductive structures. The proposed research will elucidate Antarctica’s role in the evolution of angiosperms and assembly of modern ecosystems by recovering and characterizing Late Cretaceous Antarctic angiosperms, placing them within a phylogenetic context, and testing for biogeographic links between North America and Gondwana as has been observed for animals. Fieldwork will be conducted in the James Ross Basin of West Antarctica where previous reports and preliminary data indicate the presence of Late Cretaceous-aged floras that include structurally preserved reproductive structures. The exceptional preservation of these fossils allows us to record data essential for placing them in a phylogenetic framework from which their evolutionary and biogeographical context can be determined. The taxonomically informative and well-preserved angiosperm reproductive structures within the James Ross Basin are of a crucial age and from an important geographic area for understanding the phylogenetic diversification of Southern Hemisphere angiosperms and ecosystems. Collected fossils will be examined using standard physical techniques and microCT imaging. The study of these fossils will result in the description of new species and possibly higher taxa and provide a unique perspective into the floral diversity and composition of West Antarctica during the Cretaceous. In addition, the fossils will be placed within a phylogenetic framework, which will help to elucidate which lineages were diversifying in Antarctica.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.