This paper presents and illustrates an informal paly-

Fossil zooplankton fecal pellets found in thinly bedded marine and lacustrine black shales associated with phosphate, oil, and coal deposits, link the deposition of organic matter and biologically associated minerals with planktonic ecosystems. The black shales were probably formed in the anoxic basins of coastal marine waters, inland seas, and rift valley lakes where high productivity was supported by runoff, upwelling, and outwelling.

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(14)(15)(16). The origin of metazoans, multicellular animals that relied on microbes as a food resource, is less well documented. The oldest proven metazoan body fossils are in the Ediacaran System (0.55-0.67 Gyr) of southeast Australia (17). The complexity and diversity of the fauna suggest that these animals had a history that extended further back than Ediacaran time. Furthermore, amino acid sequences in 02-binding proteins suggest the radiation of animals took place at or before 0.9-1 Gyr (18). Although older body fossils have not been identified, trace fossils such as tubes of benthic animals range to 2 Gyr (19), and fecal pellets, burrows, and trails of benthic animals are widespread in rocks younger than 0.68 Gyr (20).Detection of the time of metazoan origin has several constraints. The first is ecological: the abundance of a consumer is less than its resource, suggesting that metazoans initially were rare. The probable small size and soft-bodied nature of early consumers is another constraint that likely resulted in poor preservation in the fossil record. Metazoans, just like algae, may have begun as plankton (10,19,21). Plankton are less likely than benthos to leave body fossils or traces because of their small size, light structure, and aquatic habitat. Today, remains of planktonic animals consist primarily of fecal pellets. Microcrustacean fecal pellets predominate in modem sediment, but pellets of microscopic worms and salps as well as bodies of ciliates that resemble fecal pellets also have been identified (refs. 22-26; M. Silver, personal communication). Pellets that are predominantly from copepods accumulate today in low-energy anoxic waters of either silled marine basins or rift-valley lakes (Fig. la) (27, 28). Body parts are rare both in modem sediments and in the fossil record, although there are exceptions such as those of the Ediacara and Burgess faunas. The usual explanation for their absence is that chitin is rapidly degraded (29)(30)(31). We confirmed this by aging modem copepod chitin under nonsterile and sterile conditions at 20'C and observed complete dissolution by 16 and 32 weeks, respectively. Therefore, the history of such animals is probably going to be written by their fossilized fecal pellets.In this study, we applied a palynological technique that isolates soft microfossils in our search for remains of the oldest metazoans. Instead of studying oxide, silicate, or carbonate facies rocks (32) sampled by earlier authors, we sampled the pyrite-bearing rocks of anoxic basins. We studied kerogen in the sulfide facies because anoxic basins are modern depositional analogues that enhance organic preservation in sediments (28, 33). MATERIALS AND METHODSSamples. We solicited samples of dark gray and black laminated shale and slate from Cambrian, Proterozoic, and Archean rocks. These were from rocks that are thought to have been formed in anoxic, nonbioturbated environments. Table 1 shows ages, lithologies, and depositional environments of rocks used in this study.Acid Residues. Te...

Abstract. Successful designs to eliminate Mn from mine discharge are necessary for both restoring abandoned mine lands and permitting the mining of high sulfur coal in the eastern United States. A passive in-line system that meets Mn discharge limits was built at the discharge from the former Shade Township coal mine in south central Pennsylvania. Qualitative research on monthly changes in the microbial and algal community that removes Mn is underway. Epilithic attachment of microorganisms was analyzed on artificial (glass microscope slides) and natural substrates (limestone thin sections) that were immersed in surface water for one month periods over 6 months. Organisms attached to both glass and limestone substrates. Limestone became coated with 34-86 % more Mn than did glass surfaces. Light microscopy revealed 12 different strategies are being used by bacteria, cyanobacteria, diatoms, green algae, and fungi to oxidize Mn. The dominant method used by the epilithic community to oxidize Mn is coating of holdfasts by the iron bacterium, Leptothrix discophora, and the green alga, Ulothrix sp. Other methods for Mn removal by oxidation include coating of individual cells, filaments/sheaths/ hyphae, extracellular polysaccharides, and biofihns. The unplanned community at the site is multifaceted and extremely efficient in its Mn removal ability. Community interactions or complexity may play roles in the stability of the ecosystem and the efficiency of its Mn oxidizing ability.