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为测试一系列古生物地理学假设提供了关键，这些假设评估了过去1亿年来大规模地貌动态如何影响生物进化。自2002年以来，对坦桑尼亚西南部Rukwa裂谷盆地的年度考察揭示了新白垩纪和新生代陆生和淡水脊椎动物的显著多样性。此外，东非裂谷系西部分支（EARS）内新的构造-沉积关系的发现和特征已经牢固地确立了该地区在研究构造事件与宏观进化模式之间的相互作用方面的重要性，包括非洲大陆从中生代到新生代主要陆生脊椎动物分支的起源、多样化、古生物地理学和灭绝。该研究小组的目标是在当地和区域层面上探索地形演化与生物反应之间的关系，在东非的关键地点取样不同时间的地质单位来记录动物和植物的动态。白垩纪的新发现代表了所有主要的脊椎动物类群，包括新的哺乳动物、恐龙和鳄形动物。该团队同时发现了赤道以南唯一的晚渐新世陆生和淡水组合，保存了一种新颖多样的动物群，以保存完好的鱼类、蛇、海龟、鳄鱼、鸟类和多种哺乳动物为特征。他们的油田面积是独一无二的，在一个有限的地理区域内涵盖了K/Pg边界的两侧。应用多模态地质年代学方法揭示了东太平洋西部分支的新生代激活比先前估计的至少早1400万年，与特征更好的东部分支是准同期的。综上所述，这些结果强调了该地区在白垩纪到新生代地质和生物动态时期关于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，该小组只勘探了RRB内的一小部分矿床，最近开始对邻近盆地（例如马拉维裂谷盆地）进行勘探调查。本建议的目标是：1)为RRB和迄今未勘探的邻近子盆地的地层提供明确的地层、沉积学和沉积背景，以及含化石层段的精确年龄约束；2)进一步表征构造活动与亚盆地发育/排水模式之间的相互作用，这些相互作用导致了非洲亚赤道地区这些罕见的陆生/淡水组合；3)对野外发现的化石进行详细的解剖和系统发育研究，利用这些数据评估与中生代晚期和新生代脊椎动物类群的起源、多样化、古生物地理分布和灭绝模式有关的相互竞争的宏观进化假说。了解生物体如何应对环境变化是至关重要的，特别是考虑到今天？美国的生态系统正在经历前所未有的变化。来自化石记录的信息对于深入了解环境变化如何随时间影响动植物物种起着至关重要的作用。该项目通过对非洲大陆采样严重不足地区的地质和古生物学勘探，提供了跨越1亿年地球历史的重要新数据。东非大裂谷系的大部分地区，特别是坦桑尼亚西南部的大部分地区，受到的科学关注相对较少，但它们记录了地形（例如，裂谷、隆起地形、地表水流动）、气候变化以及这些事件对该地区的影响。5 .常住动植物。该项目考察了裂谷系统中三个不同的时间间隔，将地质数据与古生物学数据结合起来，在埋藏它们的环境背景下，组装出一幅精确的化石生物年代图。由几个美国机构的学生和教师组成的实地小组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的沉积岩分析）。这些数据将为环境变化和地球上过去生命的演变提供重要的新信息。本研究将(1)提供东非三个关键地质时间点的新古生物资料；(2)利用新的和更精确的实验室方法来约束地质背景的年龄和环境条件；(3)为美国研究人员（学生和教师）提供大量机会，作为国际跨学科研究小组的一部分，专注于整合现场和实验室方法，以表征深时间的生物多样性和环境条件；(5)通过会议演讲、网站和美国和国际博物馆场所向科学和公众传播结果。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（如适应、灭绝）提供基础见解。它还将提供基线数据供其他学科使用，包括地球物理/构造学、气候研究、计算机建模、保护以及生物和地球科学的STEM教育。本项目由地球科学理事会的沉积地质学与古生物学项目和国际综合活动办公室的国际科学与工程项目共同资助。