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Abstract: Cruziana, Gordia, Planolites, Rusophycus, and Trichophycus are common ichnological elements of the Kaili Biota. New discoveries based on the examination of 323 specimens include eldoniids, echinoderms, trilobites, monoplacophorans, and non-biomineralizing arthropods that are associated with trace fossils. Based on the observed effects of bioturbation on the preservation of five different animal groups, it is clear that infaunal scavengers/deposit feeders were periodically active on the Kaili sea floor and were able to reach historic layers yielding exceptionally preserved fossils. In general, the average level of infaunal activity is absent to moderate (Ichnofabric Index [i.i.]=1 to 3) in the Kaili substrate; by contrast, the “Phycodes beds” are completely disturbed by infaunal activity (i.i.=5). Observed burrow diameter ranges from diminutive (∼0.2mm) to normal (up to 4.2mm). Computed tomography allows us to visualize the precise geometry of the trace fossil–body fossil association in three dimensions. We concluded that although some Kaili infaunal animals could bore through the biomineralized echinoderms, they did not appear to have scavenged upon these echinoderms based on our three-dimensional reconstruction. Furthermore, Kaili burrowers can reach the historic layers containing exceptionally preserved fossils without altering soft-tissue preservation. On the other hand, we used conventional techniques to reveal that one burrow is filled with fecal pellets (100–200μm) at its terminal end. Because most burrows are filled with yellow/brown “coarse sediment”, and because there is no compositional difference between the fecal pellets and the surrounding coarse sediment within the burrow, the origin of the yellow/brown “coarse sediment” is interpreted here as parautochthonous and/or autochthonous and as a result of sediment reworking by deposit (or suspension) feeders. The relative scarcity of soft-part preservation in the Kaili Biota compared to the older Chengjiang Biota and the younger Burgess Shale Biota may be the result of post-burial bio-disturbance due to the relatively high intensity of local bioturbation. It is plausible that oxygenation in deeper sediments (facilitated by bioturbation) allowed carcasses in the Kaili biota to undergo a more extensive period of ‘normal’ decay prior to final burial than in other Cambrian Konservat-Lagerstätten. [Copyright &y& Elsevier]

Abstract: Gordia marina is the most common ichnospecies in the Kaili Biota, Guizhou, China. Among 1070 non-biomineralizing body fossils examined, more than 220 specimens in museum collections were observed to be associated with extensive Gordia traces. Approximately 55% of the discoidal animal Pararotadiscus quizhouensis are associated with Gordia. The complex courses of the burrows in the area of the body fossils and their recurvature at the periphery confirm that this association is not fortuitous. The length and complexity of the burrow are inversely proportional to the quality of soft-part preservation in the animals. Gordia makers, possibly priapulids, accessed buried carcasses by burrowing, then exploited them by deposit feeding the nutrient-rich sediments immediately above or below the planes of Pararotadiscus discs and bivalved arthropod carapaces, including Tuzoia, Canadaspis, and Waptia. [Copyright &y& Elsevier]