Revisiting the Cambrian Series 1 animal origination chronology

重温寒武纪系列 1 动物起源年表

• 批准号: 2025735
• 负责人: Jessica Creveling
• 金额: $ 37.01万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2025735&HistoricalAwards=false
• 关键词: Revisiting; Cambrian; Series; animal; origination

The oldest shelly sea creatures appeared ~540 million years ago in the ‘Cambrian explosion’. This research seeks to refine the timeline for this captivating evolutionary event. This task is harder than expected because fossils of the same organism appear at different times in different places. How can one tell which of the many fossils of the same species is oldest—and refine its evolutionary timeline—with a sparse chronology for Cambrian marine sediment deposition and fossil occurrences? This research uses a computer program to match up the globally synchronous chemical signals of carbon cycle changes preserved in the rocks hosting Cambrian fossils. Matching the chemical signals from a fossil’s location to the one Cambrian location with many dates will allow these ages to be determined via extrapolation. As most Cambrian fossil organisms are the earliest members of still-living taxonomic phyla, our research promotes the progress of scientific inquiry into the tempo of evolution within and across animal clades. This project will develop open source, interactive software for the broader geological community to align chemical records without the need for advanced coding experience; train one PhD student and three undergraduates in computational research; and develop and distribute curricula, based on this new software, to promote undergraduate quantitative literacy. The chronology for the early Cambrian radiation of small skeletal fossils arises from visual alignment of δ13Ccarb excursions at a U-Pb radiometrically calibrated, fossil barren, stratigraphic section in Morocco to excursions at richly fossiliferous, time uncertain sections elsewhere. Visual δ13Ccarb correlation methods cannot ensure unique alignments, nor a given chronology. This research adopts a dynamic programming algorithm to identify libraries of geologically permissible alignments between fossiliferous stratigraphic sections and the Moroccan δ13Ccarb–U/Pb age model. Each permissible δ13Ccarb alignment will generate a distinct chronology for the local first appearance datum (FAD) of all fossil taxa at a stratigraphic section and, thus, various combinations of local FAD chronologies will yield alternative ages for a taxon’s global FAD. The proposed research explores whether/how alternative global FAD chronologies reveal a different number of origination pulses and alternative ages for pulse initiation and duration, thereby addressing heretofore unacknowledged uncertainty in the earliest Cambrian explosion chronology.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.

最古老的雪莉海洋生物出现在5.4亿年前的“寒武纪爆炸”中。这项研究旨在完善这一迷人进化事件的时间表。这项任务比预期的要困难，因为在不同地方不同时间出现相同有机体的化石。如何判断同一物种的许多化石中的哪一个是最古老的，并完善其进化时间表，而寒武纪海洋沉积物沉积和化石发生的稀疏时间表？这项研究使用计算机程序来匹配保存在托有寒武纪化石的岩石中的碳循环变化的全球同步化学信号。将化学信号从化石的位置匹配到一个带有许多日期的寒武纪地点，可以通过外推确定这些年龄。由于大多数寒武纪化石生物是仍有生命的分类门的最早成员，因此我们的研究促进了科学探究对动物进化进化和整个动物进化进化的速度的进步。该项目将为更广泛的地质社区开发开源，交互式软件，以使化学记录保持一致，而无需高级编码体验；在计算研究中培训一名博士生和三名本科生；以及基于此新软件的开发和分布式课程，以促进本科定量素养。小型骨骼石化石早期寒武纪辐射的年代学是由Δ13CCARB游览在U-PB放射线照射校准的，化石贫瘠的，摩洛哥的地层剖面的视觉比对，往返于摩洛哥的阶层，以探索在富裕的化石，时间不确定的部分。视觉Δ13CCARB相关方法无法确保独特的比对，也不能确保给定的年表。这项研究采用了动态编程算法来识别化石地层截面与摩洛哥Δ13CCARB -U/PB年龄模型之间地质允许对齐的库。每个许可Δ13CCARB对齐将在地层部分的所有化石分类单元的局部首次出现基准（FAD）生成独特的年表，因此，局部FAD年代的各种组合将产生分类群全球FAD的替代年龄。拟议的研究探讨了/替代性全球FAD年代学是否揭示了脉冲计划和持续时间的不同数量的发起脉冲和替代年龄，从而解决了最早的寒武纪爆炸年代中迄今未被确认的不确定性，这是NSF的法定任务，并通过评估范围来表现出众多的依据。