Burgess Shale-type microfossils in the Western Canada Sedimentary Basin: tracking early Palaeozoic ecosystem evolution

现代海洋生态系统是在古生代早期动物的辐射中建立的，首先是“寒武纪大爆发”，然后是大约5000万年后的“奥陶纪生物多样性大事件”。“通过跟踪这一关键时期多样化的细节，不仅可以重建早期动物进化的动力学，还可以重建生态新奇的潜在影响。不幸的是，传统的化石记录只代表了古代生物多样性的一小部分，而著名的“软体”生物，如伯吉斯页岩太罕见了，无法提供更大规模的模式。我建议通过利用一个新的，基本上未开发的古生物学数据来源：伯吉斯页岩型微体化石来规避这些问题。像它们的宏观对应物一样，这些化石记录了非生物矿化生物的存在，但它们也扩展了观点，包括以前未记录的形式和精细特征。更重要的是，它们被证明是相当普遍的--在某种程度上，它们可以开始被用来检验宏观进化假说。对中寒武世至晚寒武世伯吉斯页岩型微体化石的系统分析将为早期演化模式提供新的基本信息，尤其是寒武纪和奥陶纪辐射之间鲜为人知的间隔。通过将这种增强的化石记录与生物海洋学和宏观生态学的原理相结合，这项研究还将为现代海洋生态系统的功能提供一个独特的进化观点。这项研究将侧重于加拿大西部沉积盆地，其中包含地球上最大，保存最完好，采样最广泛的早古生代岩石序列。除了落基山脉褶皱和冲断带中暴露的著名的含油气单元-包括伯吉斯页岩本身-地层在地下向东延伸超过1000公里，在那里他们已经被数百个石油勘探钻孔穿透。这些地下材料存放在卡尔加里，阿尔伯塔和里贾纳，萨斯喀彻温省的最先进的存储设施，并提供了一个独特的机会，通过整个中晚寒武纪系统采样，并通过一个广阔的浅水平台到大陆边缘环境暴露在落基山脉。在地下和露头的初步工作已经确定了一个精致的范围伯吉斯页岩型微体化石。更全面的取样和分析将大大提高我们对早古生代多样性、宏观演化模式以及生态系统功能和环境的共同演化的认识。

Modern marine ecosystems were established during the early Palaeozoic radiations of animals, first the 'Cambrian Explosion' and then, some 50 million years later, in the 'Great Ordovician Biodiversification Event.' By tracking the details of diversification through this critical interval, it should be possible to reconstruct not only the dynamics early animal evolution, but also the underlying effects of accruing ecological novelty. Unfortunately, the conventional fossil record represents only a fraction of ancient diversity, while famous 'soft-bodied' biotas such as the Burgess Shale are too rare to provide larger-scale patterns. I propose to circumvent these problems by exploiting a new, largely untapped source of palaeontological data: Burgess Shale-type microfossils. Like their macroscopic counterparts these fossils record the presence of non-biomineralizing organisms, but they also extend the view to include previously unrecorded forms and fine features. More significantly, they are proving to be quite common - to the extent that they can begin to be used to test macroevolutionary hypotheses. Systematic analysis of Burgess Shale-type microfossils through the Middle to Late Cambrian will shed fundamental new light on early evolutionary patterns, not least the poorly known interval between the Cambrian and Ordovician radiations. By integrating this enhanced fossil record with the principles of biological oceanography and macroecology, this study will also provide a unique, evolutionary view of how modern marine ecosystems function. This study will focus on the Western Canada Sedimentary Basin, which contains one of the largest, best preserved and most extensively sampled sequences of early Palaeozoic rocks on Earth. In addition to famously fossiliferous units exposed in the Rocky Mountain Fold and Thrust Belt - including the Burgess Shale itself - strata extend eastwards for over 1000 km in the subsurface, where they have been penetrated by hundreds of petroleum exploration boreholes. These subsurface materials are housed in state-of-the-art storage facilities in Calgary, Alberta and Regina, Saskatchewan and offer a unique opportunity to sample systematically through the whole of the Middle-Late Cambrian, and across an expansive shallow-water platform into continental-margin environments exposed in the Rocky Mountains. Preliminary work in both subsurface and outcrop occurrences has identified an exquisite range of Burgess Shale-type microfossils. More comprehensive sampling and analysis will substantially advance our understanding of early Palaeozoic diversity, macroevolutionary patterns, and the co-evolution of ecosystem function and environments.