EAPSI: Documenting the Geological Controls that Influenced the Exceptional Preservation of Trilobites from 520 Million Years Ago in Southwestern China

来自寒武纪早期（5.2亿年前）的软体生物和三叶虫的保存完好的化石部分非常罕见，但对于了解地球最早动物的进化具有重要意义。了解导致它们保存为化石的地质过程，为长时间内快速、重复的环境变化如何影响早期动物的生物多样性提供了新的视角。该项目将与中国云南大学的Xiguang Zhang博士合作，研究中国西南部两个早期寒武纪化石组合的构造和沉积控制，这些化石组合含有罕见的、保存异常完好的三叶虫和软体生物。这项合作提供了一个机会，可以获得迄今为止仅在中国发现的这些早期寒武纪化石。这些组合包含在两个不同的1米厚的泥岩层的红井哨组附近的昆明，中国。地质学上较年轻的组合包含属于Zhangshania典型物种的所有发育阶段的完全铰接到部分铰接的三叶虫;该组合还包含许多软体生物。相反，地质上更古老的组合包括三叶虫Hongshiyanaspis sp.的成熟标本集群。这项研究将涉及逐层解剖每一个1米的地层，以便确定埋藏细节（例如，方向、姿势、发音状态、软体保存的存在、群集等）将被记录下来。这些特定于地层的数据将被顺序数字化到地理信息系统（GIS）数据库中，然后在该数据库中以地层精细尺度对这些数据进行空间和时间评估，以便在两个挖掘部分之间进行埋藏学和行为学比较。这项研究将提供有关环境过程的新信息，这些环境过程导致了动物生命在其早期进化史中的特殊但罕见的保存。NSF EAPSI奖是与中国科技部合作资助的。

Well-preserved fossilized parts of soft-bodied organisms and trilobites from the early Cambrian (520 million years ago) are exceptionally rare but are significant for understanding the evolution of Earth's earliest animals. Understanding the geological processes that lead to their preservation as fossils sheds new light into how rapid, repeated environmental changes over long intervals of time affected the biodiversity of early animals. In collaboration with Dr. Xiguang Zhang at the Yunnan University in China, this project will investigate the preservational and depositional controls of two early Cambrian fossil assemblages from Southwestern China bearing rare, exceptionally well-preserved trilobites and soft-bodied organisms. This collaboration affords an opportunity to have access to these early Cambrian fossils recovered thus far only in China. These assemblages are contained within two different 1 m thick mudstone beds of the Hongjingshao Formation near Kunming, China. The geologically younger assemblage contains fully articulated to partially articulated trilobites of all developmental stages belonging to the species Zhangshania typical; this assemblage also contains numerous soft-bodied organisms. Conversely, the geologically older assemblage comprises of clusters of mature specimens of the trilobite Hongshiyanaspis sp. This study will involve dissecting each 1 m bed layer by layer so that taphonomic details (e.g., orientation, posture, state of articulation, presence of soft-bodied preservation, clustering, etc.) of the fossils will be recorded. These bed-specific data will be sequentially digitized into a Geographic Information Systems (GIS) database, where they will then be assessed spatially and temporally at this stratigraphic fine scale to allow for taphonomic and behavioral comparisons to be made between the two excavated sections. This study will contribute new information concerning the environmental processes that led to the exceptional, but rare, preservation of animal life during its early evolutionary history. This NSF EAPSI award is funded in collaboration with the Chinese Ministry of Science and Technology.