Presented by Waggoner, Ben .
Authors:
Waggoner, Ben.
Key words: Ediacara biota, Proterozoic, Vendian, Siberia
In Session 11 Paleontology (Posters) Monday, 26-Oct-98 AM in Room: Hall-E at 8:00 AM for 240 minutes.
Abstract: Ediacara-type fossils are preserved in fine-grained, organic-rich carbonate layers in the Khatyspyt Formation of the Olenek Uplift in northern Siberia. These fossils are not only preserved in three dimensions, but retain organic traces of the walls and internal structures. These traces are bacterial sapropels and do not reflect cellular-level structures. Nonetheless, they are informative about internal anatomy.
Specimens of the simple medusoids Nemiana, Planomedusites, and cf. Cyclomedusa, provided by Dr. M. A. Fedonkin, were examined in this study. Both sectioning and scanning electron microscopy of etched cross-sectional surfaces reveal a double wall in Nemiana but a single, thicker one in Planomedusites. Leiosphaeridian acritarchs are present inside the lumen of Nemiana specimens. Cross-sections through specimens were converted into three-dimensional reconstructions using the program NIH Image 1.61. This preliminary study does not solve the problem of the affinities of these simple fossils, but it does constrain their affinities: these simple medusoids are highly unlikely to be lichens or algal protists.
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