A new approach for investigating spatial relationships of ichnofossils: a case study of Ediacaran–Cambrian animal traces

Abstract — Trace fossils record foraging behaviours, the search for resources in patchy environments, of animals in the rock record.  Quantification of the strength, density and nature of foraging behaviours enables the investigation of how these may have changed through time.  Here, we present a novel approach to explore such patterns using spatial point process analyses to quantify the scale and strength of ichnofossil spatial distributions on horizontal bedding planes.  To demonstrate the utility of this approach we use two samples from the terminal Ediacaran Shibantan Member in South China (between 551 and 543 Ma) and the early Cambrian Nagaur Sandstone in northwestern India (between 539 and 509 Ma).  We find that ichnotaxa on both surfaces exhibited significant non-homogeneous lateral patterns, with distinct levels of heterogeneity exhibited by different types of trace fossils.  In the Shibantan, two ichnotaxa show evidence for mutual positive aggregation over a shared resource, su...

摘要：遗迹化石（trace fossils）记录了地质岩石记录中动物的觅食行为——即动物在斑块状环境中的资源搜寻活动。对觅食行为的强度、密度与本质进行量化分析，可揭示此类行为随地质时间的演化规律。本研究提出一种全新研究方法，借助空间点过程分析技术，量化水平沉积层面上遗迹化石（ichnofossil）的空间分布尺度与强度，以此探索上述演化模式。为验证该方法的实用性，我们选取两套沉积样品开展研究：其一为中国华南地区埃迪卡拉纪末期的石板滩段（Shibantan Member），地质年代介于551 Ma至543 Ma之间；其二为印度西北部寒武纪早期的纳古尔砂岩（Nagaur Sandstone），地质年代介于539 Ma至509 Ma之间。研究发现，两处沉积面的遗迹分类群（ichnotaxa）均呈现出显著的非均质性侧向分布模式，且不同类型的遗迹化石表现出不同程度的分布异质性。在石板滩段样品中，两类遗迹分类群表现出对共享资源的正向聚集现象，初步结果显示……