Deciphering the very early phase of angiosperm evolution using palynology

利用孢粉学破译被子植物进化的早期阶段

• 批准号: 444920835
• 负责人: Professor Dr. Ulrich Heimhofer
• 金额: --
• 依托单位: Institut für Geologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/444920835?language=en
• 关键词: Deciphering; very; early; phase; angiosperm

The timing of the first appearance of angiosperms (flowering plants) is a matter of considerable debate in palaeobotany. The fossil record clearly indicates significant diversification of crown-group angiosperms in the Early Cretaceous, with the first 10 ‒ 15 Myr being represented by fossil pollen only. However, this pre-Aptian record of angiosperm pollen is very fragmentary (based on spot samples) and often based on findings from strata lacking precise stratigraphic assignment. Given the fact that the Early Cretaceous change from gymnosperm- to angiosperm-dominated ecosystems represents one of the most dramatic turnovers in the terrestrial biotic history of the younger Phanerozoic, this scarcity of well-dated fossil evidence is startling. To fill this gap, we propose to study stratigraphic sections located in the Lusitanian Basin of Portugal, an area well known for its exceptional angiosperm mesofossils and rich pollen floras. The chosen sections cover Valanginian – Barremian strata in marine near-shore facies. Precise stratigraphic control can be achieved by the combination of existing bio- and sequence-stratigraphic information with new strontium- and carbon-isotope chemostratigraphy. Pollen assemblages will be studied with different imaging techniques including transmitted light as well as scanning electron microscopy (incl. single grain analysis). This approach will enable comparison with existing records, in particular from the Weald basin and from adjacent Portuguese mesofossil localities. Information on the broader plant community context will be obtained by studying the accompanying palynoflora. The combined chemostratigraphic and palynological approach of this proposal aims at providing new insights into the very early evolution and diversification of angiosperms and into terrestrial environmental dynamics during the Early Cretaceous.

被子植物(开花植物)首次出现的时间在古植物学中是一个有相当大争议的问题。化石记录清楚地表明，早白垩世冠群被子植物的多样性显著，最初的10-15Myr仅由化石花粉代表。然而，这种关于被子植物花粉的前阿普提亚记录是非常零碎的(基于现场样本)，而且通常基于缺乏准确地层划分的地层的发现。鉴于早白垩世从裸子植物为主的生态系统向被子植物为主的生态系统的变化代表着年轻显生目生物陆地生物史上最戏剧性的转变之一，这种准确年代化石证据的稀缺令人震惊。为了填补这一空白，我们建议研究位于葡萄牙卢西坦尼亚盆地的地层剖面，该地区以其特殊的被子植物中化石和丰富的花粉植物群而闻名。所选剖面覆盖了海相近岸相的瓦兰吉期-巴雷米期地层。通过将现有的生物和层序地层学信息与新的锶和碳同位素化学地层学相结合，可以实现精确的地层控制。花粉组合将用不同的成像技术进行研究，包括透射光和扫描电子显微镜(包括。单颗粒分析)。这种方法将能够与现有的记录进行比较，特别是来自Weald盆地和邻近的葡萄牙中土地区的记录。有关更广泛的植物群落背景的信息将通过研究伴随的孢粉植物群而获得。这一建议的化学地层学和孢粉学相结合的方法旨在为被子植物的非常早期的进化和多样化以及早白垩世期间的陆地环境动力学提供新的见解。