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An enigmatic stepwise increase in oxygen in the late Precambrian is widely considered a prerequisite for the expansion of animal life. Accumulation of oxygen requires organic matter burial in sediments, which is largely controlled by the sheltering or preservational effects of detrital clay minerals in modern marine continental margin depocenters. Here, we(More)
Cambrian konservat-lagerstätten are the most significant fossil deposits for our understanding of the initiation of Phanerozoic life. Although many modes of preservation may occur, these deposits most frequently contain nonmineralized fossils preserved in the form of kerogenized carbon films, a rare yet important taphonomic pathway that has not previously(More)
The trace fossil record is important in determining the timing of the appearance of bilaterian animals. A conservative estimate puts this time at approximately equal 555 million years ago. The preservational potential of traces made close to the sediment-water interface is crucial to detecting early benthic activity. Our studies on earliest Cambrian(More)
There was a major diversification known as the Ordovician Radiation, in the period immediately following the Cambrian. This event is unique in taxonomic, ecologic and biogeographic aspects.While all of the phyla but one were established during the Cambrian explosion, taxonomic increases during the Ordovician were manifest at lower taxonomic levels although(More)
The most abundant taxon of the Neoproterozoic soft-bodied biota near Ediacara, South Australia, occurs as clusters of similarly sized individuals, which suggests synchronous aggregate growth by spatfall. Tubes of Funisia dorothea gen. et sp. nov. were anchored within the shallow, sandy sea bed and lived in dense, typically monospecific concentrations. Tubes(More)
Fossils of the Ediacara biota offer our earliest insight into diverse macroscopic life on this planet. In particular, given the diversity and range of exquisite soft-bodied preservation, the potential for unraveling aspects of the paleobiology and paleoecology is great. Clearly, however, there can be a taphonomic overprint that dictates how complete the(More)
The past two decades have seen extensive analyses of the taxonomic severity of major biodiversity crises in geologic time. In contrast, we propose here an alternative analysis of the ecological severity of biodiversity crises. It is clear that the ecological impacts of the five Phanerozoic biodiversity crises were not all the same. Ranking the five(More)
—Relative abundance data are of primary importance in paleoecology, but it is not always obvious how they should be interpreted. Because relative abundance is expressed as a proportion of the total sample, change in the abundance of one group necessarily changes the relative abundance of all groups in the sample. There are two possible interpretations for a(More)
Kullingia is considered a key taxon in demonstrating the presence of terminal Protero-zoic–early Cambrian chondrophorine hydrozoans. However, Kullingia concentrica from the Lower Cambrian of northern Sweden possesses several features that show that it is not a body fossil but that it was formed by current or wave-induced rotation of an anchored tubular(More)