Reconstructing the Paleocommunity from the Fossil Assem- blage: Comparative Analysis of Taphonomy and Time Averagingin Modern Death Assemblages of the Marine Environment

解释化石记录的一个主要障碍是对其中的偏差理解不足，这些偏差是由(1)生物原始组合的地语学改变和(2)时间上不同的动物群的混合或时间平均造成的。该项目的目的是通过对墨西哥湾和邻近水域的主要沉积环境进行地貌学和时间平均的比较研究，提高我们对这些偏差的理解。在过去的6年里，在德克萨斯州海湾和德克萨斯州大陆架选定的群落进行了采样和分析，使用了动物学家（用于生活群落）和古生物学家（用于死亡组合）可用的最佳技术。研究的参数包括分类组成、营养结构、多样性、种群动态、生物量以及物理干扰现象和生物相互作用对群落结构的影响。研究的过程包括壳材料的同源修饰和损失、壳材料的局部迁移和时间平均。对于这些过程如何影响生物群落死亡组合的形成，以及在古生态重建过程中上述参数的使用，已经为德克萨斯沿海地区开发了一个很好的工作模型，并扩展到陆架和上斜坡。在这些地区的一系列主要沉积环境中进行了详细的触相分析。我们将首次对时间平均进行详细的比较分析，从而深入地扩展这一分析。我们建议将研究范围扩大到墨西哥湾及邻近水域的其他EOD，从而扩大这一分析的范围。通过这种方式，我们可以研究化石组合是如何在海洋环境中形成的，并确定为德克萨斯海湾和德克萨斯大陆架的死亡组合开发的模型在多大程度上适用于更大比例的化石记录。

A major impediment in the interpretation of the fossil record has been the inadequate understanding of the biases in it caused (1) by the taphonomic alteration of the original assemblage of living organisms and (2) by the mixing or time averaging of temporally distinct faunas. The objective of this project is to improve our understanding of these biases by a comparative study of taphonomy and time averaging among the major environments of deposition found in the Gulf of Mexico and adjacent waters. Over the past 6 years, selected communities in Texas bays and the Texas continental shelf were sampled and analyzed using the best techniques available to both zoologists (for the living community) and paleontologists (for the death assemblage). Parameters investigated included taxonomic composition, trophic structure, diversity, population dynamics, biomass and the influence of physical disturbance phenomena and biological interactions in determining community structure for both the living community and the death assemblage. Processes studied included taphonomic modification and loss of shell material, local transportation of shell material, and time averaging. A good working model of how these processes affect the formation of the death assemblage from the living community and the use of the parameters listed above during paleoecological reconstruction has been developed for the Texas coastal zone and extended out onto the shelf and upper slope. A detailed taphofacies analysis has been conducted in a suite of major environments of deposition in these same areas. We will extend this analysis in depth by including, for the first time, a detailed comparative analysis of time averaging. We propose to extend this analysis in scope by broadening the study to include additional EOD's within the Gulf of Mexico and adjacent waters. In this way, we can investigate how fossil assemblages form in the marine environment and determine how broadly applicable the model developed for death assemblages in Texas bays and the Texas shelf is to a much larger fraction of the fossil record.