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PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002Zhao, 1992). The benthic biota was also tiered(Clapton and Narbonne, 2002) with frond animalsstanding above the others. In analogous modernsoft-bodied communities (Fig. 5), predation is acommon strategy (Madin, 1988; Carre et al., 1989;Mills, 1993, 1995). The Ediacaran biota includedsimilar cnidarian- and ctenophore-like animals(Gehling, 1988; Fedonkin, 1992; Jenkins, 1992;Wood et al., 2002). Ediacara was certainly nopeaceful garden!Trails and scratch marks indicate substratesearch and feeding strategies. Large Dickinsonia andYorgia were found with trails behind them (Ivantsovand Fedonkin, 2001); the presence of digestiveorgans on their undersides (Dzik and Ivantsov,2002), marks on the underlying sediment, and thesmoothing of the surface under the fossils indicatethat they groomed the substrate and ingested food.Trace fossils representing locomotion and feeding,chiefly at the sediment surface (Crimes, 1992) orwithin the mats (Seilacher, 1999), are common inEdiacaran biotas, and fecal pellets occur on bedsurfaces (Fedonkin and Runnegar, 1992), showingdigestion and excretion. Scratches on the sedimentin front of the anterior end of Kimberella wereinterpreted as feeding marks (Seilacher, 1999).The Ediacaran biota was the earliest fullyfunctioning animal community with herbivores,detritovores, and predators on both benthic andplanktic resources. They were not especiallyunusual although some major feeding types hadnot yet evolved by the Neoproterozoic, such asinfaunal bioturbation. Nevertheless, a variety offeeding strategies was present, all based onmicroorganism primary producers. These trophicstructures presaged the more complex ones inPhanerozoic and modern marine communities(Table 3, 4).What initiated the evolution of the Ediacaranbiota? The trophic developments suggest thatresources not previously available either in typeor abundance played a role, although animal andmicrobial ancestors had to have been present andresponsive to selection. The waning Snowball IIFIGURE 5—A modern soft-bodied community in Jellyfish Lake, Palau, where predation is rampanteven though some organisms may contain photoendosymbionts. Here anemones (Entacmaeamedusivora) attached to a log capture the jellyfish Mastigias (arrows) as they float into contact with thetentacles (Fautin and Fitt, 1991). No evidence of the consumed jellyfish remains as they are eatenwhole. Mastigias possesses dinoflagellate endosymbionts, but it also captures its own food. The jellyfishon the right is about 15 cm long. (Photo by J. H. Lipps.)80