| Analysis of the sedimentology of the Burgess Shale's Greater Phyllopod bed (GPB) as well as palynology of the Burgess Shale and bounding Formations has shed more light on our breadth of understanding of depositional and ecological setting.; High resolution sedimentologic analysis of the GPB was conducted in order to compare the competing depositional models as well as consideration that the biota preserved at the GPB is in situ. The paucity of trace fossils remains the most substantial fact suggesting that the majority of GPB biota is allochthonous. There are, however, some species that appear to be in situ. Sediment patterns such as massive beds with high clay content are inconsistent with deposition via turbidity currents, and fluidized mud-flows respectively. The clinoform geometry of the basin is most consistent with transport of sediment off the escarpment perpendicular to the strike of the platform edge. Storm generated backcurrents likely transported the mud and majority of fossils from their original habitat the platform high above the GPB.; Palynologic analysis of a few of the bounding formations in the vicinity of the Burgess Shale fossil beds as well as detailed examination of the GPB has revealed one new genus, Asperitas, and several new species of acritarchs including, Acrum incompostum, A. minutum , Asperitas anaideia, A. burgessensis, Dictyotidium acanthodes, D. cerionites, Dictyotidium? fraudulentum, D. microreticulatum, D. monogranulum, Micrhystridium cylindrum, Trachysphaeridium bicircummunum and T. reticulatum.; Palynologic analysis by delicate acid-maceration also permitted the isolation of organic carbon cuticle, and abundant acritarchs directly from the arthropod Marrella splendens. The acritarchs are found in higher concentrations in association with the Marrella than in the matrix immediately surrounding the organism. It is concluded that Marrella was a filter-feeder composing a critical trophic link in this Middle Cambrian ecosystem. The presence of delicate organic carbon structures highlights the fact that organic carbon preservation contributed to the extraordinary preservation of the fossils of the Burgess Shale. |
