Collaborative Research: 100 million Years of Biotic and Tectonic Evolution in the Western Branch of the East African Rift System

合作研究：东非裂谷系西支一亿年的生物和构造演化

• 批准号: 1349592
• 负责人: William Clyde
• 金额: $ 1.91万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349592&HistoricalAwards=false
• 关键词: Collaborative; Research; 100; million; Years

The fossil record of sub-Saharan Africa holds keys for testing a range of paleobiogeographic hypotheses that assess how large-scale landform dynamics have influenced biotic evolution over the past 100 million years. Annual expeditions since 2002 to the Rukwa Rift Basin in southwestern Tanzania have revealed a remarkable diversity of new Cretaceous and Cenozoic terrestrial and freshwater vertebrates. Moreover, the discovery and characterization of novel tectono-sedimentary relationships within the Western Branch of the East African Rift System (EARS) have firmly established the importance of this region for examining the interplay between tectonic events and macroevolutionary patterns, encompassing the origin, diversification, paleobiogeography, and extinction of major terrestrial vertebrate clades on continental Africa from the Mesozoic well into the Cenozoic Era. This research group aims to explore the relationship between landform evolution and biotic response in deep time at both local and regional levels, sampling time-distinct geological units to document faunal and floral dynamics at key points in eastern Africa.New Cretaceous discoveries from this project represent all major vertebrate groups, including novel mammals, dinosaurs, and crocodyliforms. The team has concurrently identified the only late Oligocene terrestrial and freshwater assemblage south of the equator, preserving a novel and diverse fauna characterized by spectacularly preserved examples of fishes, snakes, turtles, crocodylians, birds, and a diversity of mammals. Their field area is unique in encompassing both sides of the K/Pg boundary within a restricted geographic area. Multi-modal geochronologic approaches have been applied to reveal that Cenozoic activation of the Western Branch of the EARS initiated at least 14 million years earlier than previously estimated, penecontemporaneously with the better characterized Eastern Branch. Taken together, these results underscore the significance of this region for testing paleobiogeographic hypotheses regarding the origin and distribution of Gondwanan vertebrates during the geologically and biologically dynamic period from the Cretaceous into the Cenozoic. To date the team has explored only a fraction of the deposits within the RRB, and has recently initiated exploratory surveys into adjacent basins (e.g., the Malawi Rift Basin). The goals of this proposal are: 1) to provide explicit stratigraphic, sedimentologic, and depositional context for strata in the RRB and hitherto unexplored adjacent sub-basins, together with precise age constraint for fossil-bearing intervals; 2) to further characterize the interplay between tectonic activity and sub-basin development/drainage patterns that resulted in these rare terrestrial/freshwater assemblages from sub-equatorial Africa; and 3) to conduct detailed anatomical and phylogenetic studies on fossils recovered from the field, using these data to assess competing macroevolutionary hypotheses related to the origin, diversification, paleobiogeographic distribution, and extinction patterns of late Mesozoic and Cenozoic vertebrate groups. Understanding how organisms respond to environmental change is of critical importance, particularly considering that today?s ecosystems are undergoing an unprecedented rate of change. Information from the fossil record plays an essential role for providing a deeper perspective on how environmental changes influence animal and plant species over time. This project provides important new data from an interval spanning 100 million years of Earth's history, through geological and paleontological exploration of a critically undersampled region on the African continent. Large portions of the large East African Rift System, particularly in southwestern Tanzania, have received relatively little scientific attention, yet they record dramatic changes in landform (e.g., rifting, uplift topography, surface water flow), climate change, and the impact of these events through time for the region?s resident animals and plants. This project examines three distinct time intervals within the rift system, integrating geological data with paleontological data to assemble a precisely dated picture of fossil organisms within the environmental settings that entombed them. Field teams consisting of students and faculty from several US institutions will conduct expeditions in the study area to collect paleontological data (fossils) and geological samples (for age-dating of rock units and sedimentary rock analyses that document environmental setting). These data will provide important new information on environmental change and the evolution of past life on the planet. This research will (1) provide new paleobiological data from eastern Africa at three key points in geologic time; (2) utilize new and more precise laboratory approaches to constrain the age and environmental conditions of the geological settings; (3) offer numerous opportunities for US researchers (students and faculty) to participate as part of an international, interdisciplinary research group focused on integrating field and laboratory approaches for characterizing biodiversity and environmental conditions in deep time, and (5) disseminate results to scientific and public audiences via conference presentations, websites, and museum venues in the US and internationally. This research will impact our understanding of animal and plant distributions (biogeography), ecological conditions of past environments (paleoecology), and provide fundamental insights into key topics in evolutionary biology (e.g., adaptation, extinction). It will also contribute baseline data for use by other disciplines, including geophysics/tectonics, climate studies, computer modeling, conservation, and STEM education in biological and Earth sciences.This program of work is jointly funded by the Sedimentary Geology & Paleobiology Program of the Geosciences Directorate, and by the International Science & Engineering Program of the Office of International & Integrative Activities.

撒哈拉以南非洲的化石记录是检验一系列古生物地理假说的关键，这些假说可以评估过去一亿年来大规模地貌动态如何影响生物进化。自 2002 年以来，每年对坦桑尼亚西南部鲁夸裂谷盆地的考察都揭示了新白垩纪和新生代陆地和淡水脊椎动物的显着多样性。此外，东非裂谷系（EARS）西部分支内新的构造-沉积关系的发现和表征，牢固地确立了该地区对于研究构造事件和宏观演化模式之间相互作用的重要性，包括起源、多样化、古生物地理学，以及从中生代到新生代非洲大陆主要陆生脊椎动物进化枝的灭绝。该研究小组旨在探索地方和区域层面的深时地貌演化与生物反应之间的关系，对不同时间的地质单元进行采样，以记录东非关键点的动物和花卉动态。该项目的白垩纪新发现代表了所有主要的脊椎动物群，包括新奇的哺乳动物、恐龙和鳄鱼。该团队同时发现了赤道以南唯一的渐新世晚期陆地和淡水生物群落，保存了一种新颖而多样的动物群，其特征是保存完好的鱼类、蛇、海龟、鳄鱼、鸟类和多种哺乳动物。 他们的球场区域是独一无二的，在有限的地理区域内涵盖了 K/Pg 边界的两侧。多模态地质年代学方法已被用来揭示EARS西支的新生代激活比之前估计的早至少1400万年，与特征更好的东支几乎同时期。总而言之，这些结果强调了该地区对于测试有关白垩纪到新生代地质和生物动态时期冈瓦纳脊椎动物起源和分布的古生物地理学假设的重要性。迄今为止，该团队仅勘探了RRB内的一小部分矿床，并且最近开始了对邻近盆地（例如马拉维裂谷盆地）的勘探调查。该提案的目标是： 1) 为 RRB 和迄今为止未勘探的邻近次盆地的地层提供明确的地层学、沉积学和沉积背景，以及含化石层段的精确年龄限制； 2) 进一步描述构造活动与次盆地发育/排水模式之间的相互作用，这些相互作用导致了赤道以南非洲的这些罕见的陆地/淡水组合； 3）对从野外发现的化石进行详细的解剖学和系统发育研究，利用这些数据评估与晚中生代和新生代脊椎动物群的起源、多样化、古生物地理分布和灭绝模式相关的相互竞争的宏观进化假设。了解生物体如何应对环境变化至关重要，特别是考虑到当今的生态系统正在经历前所未有的变化。化石记录中的信息对于更深入地了解环境变化如何随时间影响动植物物种发挥着至关重要的作用。该项目通过对非洲大陆采样严重不足的地区进行地质和古生物学探索，提供了跨越一亿年地球历史的重要新数据。东非大裂谷系统的大部分地区，特别是坦桑尼亚西南部，受到的科学关注相对较少，但它们记录了地貌（例如裂谷、隆起地形、地表水流）、气候变化以及这些变化的影响的巨大变化。该地区居民动植物随时间变化的事件。该项目研究了裂谷系统内的三个不同的时间间隔，将地质数据与古生物学数据相结合，以在埋藏它们的环境背景下组装出化石生物的精确日期图片。由来自美国多家机构的学生和教师组成的实地团队将在研究区域进行考察，收集古生物学数据（化石）和地质样本（用于岩石单元的年龄测定和记录环境设置的沉积岩分析）。这些数据将提供有关环境变化和地球上过去生命演化的重要新信息。这项研究将（1）提供东非地质时期三个关键点的新古生物学数据； (2) 利用新的、更精确的实验室方法来限制地质环境的年龄和环境条件； (3) 为美国研究人员（学生和教师）提供大量机会，让他们作为国际跨学科研究小组的一部分参与其中，该研究小组专注于整合现场和实验室方法，以深入表征生物多样性和环境条件，以及 (5) 将结果传播给科学界通过美国和国际上的会议演示、网站和博物馆场所向公众和观众展示。这项研究将影响我们对动植物分布（生物地理学）、过去环境的生态条件（古生态学）的理解，并为进化生物学的关键主题（例如适应、灭绝）提供基本见解。它还将提供基线数据供其他学科使用，包括地球物理学/构造学、气候研究、计算机建模、保护以及生物和地球科学中的 STEM 教育。该工作计划由沉积地质学和古生物学计划共同资助地球科学理事会和国际与综合活动办公室的国际科学与工程计划。