Palaeopascichnustype fossils

Palaeopascichnus and numerous other similar forms are some of the more familiar structures that should be removed from the tally of Ediacaran trace fossils (Haines, 1990; Gehling et al., 2000; Jensen, 2003; Seilacher et al., 2003; Shen et al., in press). The exact morphology and affinities of these organisms are still unclear. Gehling et al. (2000) found tantalizing if inconclusive connections to Aspidella, whereas Seilacher et al., (2003) linked them to xenophyophoran protists. Palaeopascichnus preserved in carbonates have been interpreted as stratiform stromatolites (Runnegar, 1995), or compared to algae (Haines, 1990). What is clear is that these were organisms growing strictly in two dimensions (though some show spiral twisting) and possibly in direct connection to microbial mats. Palaeopascichnus and Yelovichnus are clearly identical. Other Ediacaran structures described as Neonereites renarius, Neonereites biserialis, Neonereites uniserialis and Catellichnus also are related structures. Orbisiana represents a further preservational variation in shales (Jensen, 2003), and this may apply also to Catenasphaerophyton and Serisphaera from the Ediacaran of South China (see Xiao and Dong, this volume). The same is probably the case for some but not all reports of Intrites (see Mcllroy et al, 2005).

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