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

9814845 Valentine这项研究将解决与动物早期历史相关的三个方面的问题：新元古代遗迹化石及其制造者的性质;现代遗迹和软体动物的埋藏学;以及基底后生动物分支的进化。它将继续进行新元古代和现代痕迹生物的比较研究，对身体化石和双胚层后生动物的现代埋藏学进行比较观察，并对早期分支后生动物群进行分子系统发育分析。虽然许多研究者认为新元古代的遗迹化石是由两侧生动物造成的，但前两侧生双胚层动物也能留下类似的遗迹。同样地，许多现代刺胞动物，虽然未分化，有刚性和/或致密的身体，将形成实验埋藏比较的基础上，一些新元古代的身体化石。基底后生动物的分子序列表明，两侧动物是姐妹组的盘形动物，刺胞动物是姐妹这两个群体的组合。本提案中概述的工作将检验这些假设并提出适当的新假设。

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.