History of biomineralization in early metazoan clades and the taphonomic phosphatization window at the PC-C boundary

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The proposed project aims at investigating the evolution of biomineralization in early metazoans at the Pc-C boundary interval and to compare the detailed successions of skeletal and softbodied fossil communities at neighbouring cratons and terranes of western Gondwana (Yangtze and Tarim, Kazakh terranes, Yili Block). Central to this project will be the revision of the skeletal fossil record from poorly studied regions, such as Kazakhstan and Tarim. The project will develop a high-resolution biostratigraphic correlation chart for this region, which also allows the determination of durations of hiati. The appearance data of skeletal fossils in the West Gondwanan Region will be compared with published global data and estimates of divergence dates of major metazoan clades by molecular biology. Key to the project will be the discrimination between true biomineralization and diagenetic mineralizations. The appearance of biomineralization (siliceous, phosphatic, carbonatic, limonitic) in various metazoan clades at the PC-C transition will be studied in detail because the expression of biomineralized skeletons represents major biotic events in the early history of metazoans. Tracing of possible soft-bodied Orsten-type deposits and comparison with deposits described in the current project phase (embryos, polyps etc.) will constitute a major aspect of the proposed study. Nano-X-ray CT and en-SEM shall be applied to further study the detailed architecture of sclerites, scleritomes and especially Orsten-type fossils (“soft-bodied” fossils and fossil embryos).