Evolutionary History of Crinoid Stalks: Architecture, Connective Tissues, Biomechanics and Taphonomy

近年来对现存海百合茎秆的形态、精细结构、分类和功能形态的研究为重新审视古生代海百合茎秆的形态和功能提供了必要的信息。通过描述古生代分类群中结缔组织（韧带）的分布，可以记录茎的形态模式。这将通过检查柱状体的微观结构（立体）和解释破碎茎的分类模式来完成。形态学数据随后将用于百合茎的功能分析，将茎建模为悬臂梁。我们已经开发和测试的大光束偏转的修改模型将允许我们检查不同的茎结构如何响应不同的能量制度。这些结果不仅可以作为古生态学的工具，重新解释海百合在不同环境中的分布格局，而且还可以为检验高等海百合类群之间关系的假设提供新的特征（结缔组织的类型和定位模式）。

Recently completed studies on the morphology, fine-structure, taphonomy, and functional morphology of stalks of living crinoids provide the necessary information to reexamine the morphology and function of stalks of Paleozoic crinoids. Patterns of stalk morphology will be documented by describing the distribution of connective tissue (ligaments) in the stalks of Paleozoic taxa. This will be done by examining the microstructure (stereom) of columnals, and by interpreting taphonomic patterns of fragmented stalks. The morphological data will then be used in a functional analysis of crinoid stalks, with the stalk modeled as a cantilever beam. A modified model for large beam deflections which we have developed and tested will allow us to examine how different stalk architectures responded to different energy regimes. These results will serve not only as a paleoecological tool, to reinterpret, for example, the distributional patterns of crinoids among different environments, but should also provide new characters (types and patterns of positioning of connective tissue) for testing hypotheses of relationship among higher crinoid taxa.