Characterizing Metazoa of the Neoproterozoic by Investigating the Taphonomy and Phylogeny of Modern Animals

本研究将解决与动物早期历史有关的三个方面的问题：新元古代痕迹化石的性质及其制造者；现代痕迹与软体动物的分类学；和基础后生动物进化枝的系统发育。继续开展新元古代与现代造迹生物的比较研究，双质体后生动物体化石与现代地形学的比较观察，后生动物早期分支类群的分子系统发育分析。尽管许多研究者认为新元古代的痕迹化石是由双边动物留下的，但前双边动物也可以留下类似的痕迹。同样，许多现代刺胞动物，虽然没有骨骼化，但有坚硬和/或致密的身体，这将成为与一些新元古代身体化石进行实验地形学比较的基础。基础后生动物的分子测序表明，双边动物是placozoans的姐妹类群，刺胞动物是这两个类群的姐妹类群。本提案中概述的工作将测试这些假设并开发适当的新假设。

9814845Valentine This research will address three aspects of problems related to the early history of animals: the nature of Neoproterozoic trace fossils and their makers; the taphonomy of modern traces and soft-bodied animals; and the phylogeny of basal metazoan clades. It will continue comparative studies of Neoproterozoic and modern trace-making organisms, comparative observations of body fossils and modern taphonomy of diploblastic metazoans, and the molecular phylogenetic analysis of the early branching metazoan groups. Although many investigators have assumed that Neoproterozoic trace fossils were made by bilaterian animals, pre-bilaterian diploblastic animals can make similar kinds of traces. Likewise, many modern cnidarians, although unskeletonized, have rigid and/or dense bodies that will form the basis for experimental taphonomic comparisons to some Neoproterozoic body fossils. Molecular sequencing of basal metazoans suggests that bilaterians are the sister group to placozoans, and that cnidarians are sister to these two groups combined. The work outlined in this proposal will test these hypotheses and develop appropriate new ones.