Cretaceous Vertebrates from Madagascar: A Window into the Biogeographic and Plate Tectonic History of Gondwana

马达加斯加的白垩纪脊椎动物：了解冈瓦纳生物地理和板块构造历史的窗口

• 批准号: 1664432
• 负责人: David Krause
• 金额: $ 26万
• 依托单位: Denver Museum of Nature and Science
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1664432&HistoricalAwards=false
• 关键词: Cretaceous; Vertebrates; Madagascar; Window; into

Cretaceous Vertebrates from Madagascar: A Window into the Biogeographic and Plate Tectonic History of GondwanaDavid Krause, Stoneybrook, EAR-1528273Patrick O'Conner, Ohio University, EAR-1525915This proposal is jointly funded by the Sedimentary Geology and Paleobiology Program (EAR/GEO) and the Africa, Near East & South Asia Program/Office of International Science and Engineering (OD). ABSTRACTNon-technical ExplanationThe latter half of the Mesozoic Era witnessed profound changes in the configuration of landmasses that comprised the southern supercontinent Gondwana, with dramatic consequences for the associated vertebrate faunas. Madagascar lay near the center of Gondwana as it fragmented into its component parts. This proposal seeks to continue a project designed to discover and describe vertebrate fossils in a sequence of Cretaceous strata on the island, to analyze their paleobiology, to place them in phylogenetic and geologic context, and to employ them in testing biogeographic and plate tectonic hypotheses related to Gondwana as a whole and Madagascar in particular. PIs work in the Cretaceous of Madagascar is only at the very beginning of reaching its potential. To date, they have quintupled the previously known species diversity of Late Cretaceous vertebrates from the island and have discovered some of the most complete and spectacularly preserved specimens of Late Cretaceous vertebrates from the southern hemisphere and, indeed, the world. Many new taxa have been named and described. But much remains to be done in the vast expanses of paleontologically and geologically unexplored Cretaceous rocks of Madagascar. Many taxa are known by only fragmentary remains; many others are still to be discovered. With continued work, PIs are confident that Madagascar's Cretaceous vertebrate fauna will become one of the best known and best contextualized from the southern hemisphere and one of the primary standards against which other Gondwanan faunas of Cretaceous age are compared.Technical DescriptionPIs propose to continue collecting terrestrial and freshwater vertebrate fossils of latest Cretaceous age from the Berivotra Study Area of the Mahajanga Basin of northwestern Madagascar, which continues to produce exquisite material of poorly known taxa and specimens of new taxa. Although they have published many detailed anatomical, functional, and phylogenetic analyses of taxa known from this basin, many more have been initiated and remain to be completed (in particular, on albuloid and amiid fishes, crocodyliforms, pterosaurs, sauropod and abelisauroid theropod dinosaurs, birds and other paravian theropods, and mammals). Some of this work will entail histological sampling, thus enabling a comparative analysis of ecosystem-scale, inter-element histological variation within single vertebrate skeletons and testing of hypotheses related to possible responses and growth history adaptations of taxa that are phylogenetically constrained, but which exhibit a wide array of morphological and functional specializations. PIs also propose to continue developing newly discovered field areas in the Mahajanga Basin, which are yielding new taxa of roughly the same age but from different paleoenvironmental settings. Finally, they propose to expand their efforts into the Morondava Basin of western Madagascar, where brief expeditions in 2010 and 2012 yielded important finds and demonstrated the potential for many more from strata older than those yielding fossils in the Mahajanga Basin. Discoveries from these earlier horizons will provide a deeper temporal context with which to address biogeographic and plate tectonic hypotheses. Indeed, PIs discoveries continue to have profound implications for the biogeographic history of the extant and extinct Malagasy fauna and for the relative importance of dispersal and vicariance during Gondwanan fragmentation. One of their overarching goals is to provide a key building block for reconstructing Gondwanan biogeographic history in the form of a temporally controlled, well-sampled vertebrate fauna from the Cretaceous of Madagascar analyzed in a rigorous phylogenetic framework, and within the context of accurate paleogeographic reconstructions. It remains a priority to conduct detailed stratigraphic, sedimentologic, and taphonomic studies of all sampled horizons in order to provide temporal control as well as paleoenvironmental and paleoclimatic context. More specifically, PIs propose to conduct: (1) a comprehensive analysis of Maevarano Formation taphonomy that will provide taxonomic summaries and maps for each major quarry, and will detail the preservation of the Maevarano Formation?s exceptionally-preserved vertebrate record; (2) a comprehensive report on the geochemistry and micromorphology of exceptionally-preserved paleosols and associated fluvial sediments in the Masorobe and Anembalemba members of the Maevarano Formation, which will provide critical insights into paleoclimate; (3) a study focused on trace fossils discovered in the Maevarano Formation, specifically back-filled burrows associated with an entombed carcass (subterranean scavenging); and (4) a study clarifying and formalizing the lithostratigraphy of Upper Cretaceous horizons in the Morondava Basin.

来自马达加斯加的白垩纪脊椎动物：了解贡德瓦生物地理和板块构造史的窗口David Krause，Stoneybrook，EAR-1528273Patrick O‘Conner，Ohio University，EAR-1525915这项建议由沉积地质学和古生物学计划(EAR/GEO)和非洲、近东和南亚计划/国际科学与工程办公室(OD)共同资助。非技术解释中生代后半期见证了构成南部超大陆冈瓦那的陆块结构的深刻变化，给相关的脊椎动物群带来了戏剧性的后果。马达加斯加位于冈瓦那的中心附近，因为它分裂成几个组成部分。这项提议旨在继续开展一个项目，旨在发现和描述该岛白垩纪地层序列中的脊椎动物化石，分析它们的古生物学，将它们置于系统发育和地质背景中，并利用它们测试与整个冈瓦那特别是马达加斯加有关的生物地理和板块构造假说。马达加斯加白垩纪的PIS工作才刚刚开始发挥其潜力。到目前为止，他们已经将岛上已知的晚白垩世脊椎动物的物种多样性增加了五倍，并发现了南半球乃至世界上一些最完整、保存最完好的晚白垩世脊椎动物标本。许多新的分类群已被命名和描述。但在马达加斯加广袤的古生物学和地质学上尚未勘探的白垩纪岩石中，仍有许多工作要做。许多分类群仅由零碎的遗骸所知，其他许多分类群仍有待发现。随着持续的工作，PIS相信马达加斯加的白垩纪脊椎动物动物群将成为南半球最著名和最具背景的动物群之一，也是与其他白垩纪冈德瓦动物群进行比较的主要标准之一。PIS建议继续从马达加斯加西北部Mahajanga盆地的Berivotra研究区收集最新白垩纪时代的陆地和淡水脊椎动物化石，该地区继续生产鲜为人知的分类群和新分类群标本的精美材料。虽然他们已经发表了许多关于该盆地已知的分类群的详细的解剖学、功能和系统发育分析，但还有更多的分析已经启动并仍有待完成(特别是关于白鳍鱼和米亚鱼、鳄鱼、翼龙、蜥脚类和Aelisauid兽脚类恐龙、鸟类和其他副禽类兽脚类恐龙和哺乳动物的分析)。其中一些工作将需要组织学采样，从而能够对生态系统规模、单个脊椎动物骨骼内的元素间组织学差异进行比较分析，并测试与可能的反应和分类群的生长历史适应有关的假设，这些分类群受到系统发育的限制，但表现出广泛的形态和功能专业化。PIS还建议继续开发Mahajanga盆地新发现的田野地区，这些地区正在产生年龄大致相同但来自不同古环境背景的新类群。最后，他们提议将努力扩展到马达加斯加西部的Morondava盆地，2010年和2012年的短暂探险在那里取得了重要发现，并证明了从比Mahajanga盆地产生化石的地层更古老的地层中发现更多化石的潜力。这些早期层位的发现将为解决生物地理和板块构造假说提供更深层次的时间背景。事实上，PI的发现继续对现存和灭绝的马达加斯加动物群的生物地理史以及贡德瓦南碎片化期间扩散和替代的相对重要性产生深远影响。他们的主要目标之一是为重建冈德瓦南生物地理历史提供一个关键的组成部分，以时间控制的、采样充分的马达加斯加白垩纪脊椎动物群的形式，在严格的系统发育框架下进行分析，并在准确的古地理重建的背景下进行分析。为了提供时间控制以及古环境和古气候背景，对所有采样层位进行详细的地层学、沉积学和挖掘学研究仍然是当务之急。更具体地说，PIS建议进行：(1)对梅瓦拉诺组的全面分析，将提供每个主要采石场的分类摘要和地图，并将详细说明梅瓦拉诺组的保存？S异常保存的脊椎动物记录；(2)关于梅瓦拉诺组马索罗贝和阿涅巴伦巴段保存异常完好的古土壤和相关河流沉积的综合报告，这将提供对古气候的关键洞察；(3)重点研究在马瓦拉诺组中发现的痕迹化石，特别是与埋藏身体有关的回填洞穴(地下清理)；(4)对莫伦达瓦盆地上白垩统层位的岩石地层进行了厘清和形式化研究。