Trace Fossils From the Precambrian and Basal Cambrian

Glaessner, Martin F.

doi:10.1111/j.1502-3931.1969.tb01258.x

Cited by 177 publications

(92 citation statements)

References 21 publications

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“…Rocks with known Late Proterozoic body fossils include the Ediacaran System with faunas represented in Australia, Africa, the Soviet Union, and other localities (17,(66)(67)(68) (19,69,70). Sedimentary structures interpreted as trails and burrows also have been located, but their identity is debated (20,71).…”

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confidence: 99%

Pellet microfossils: Possible evidence for metazoan life in Early Proterozoic time

Robbins

Porter

Haberyan

1985

Proc. Natl. Acad. Sci. U.S.A.

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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...

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confidence: 99%

Pellet microfossils: Possible evidence for metazoan life in Early Proterozoic time

Robbins

Porter

Haberyan

1985

Proc. Natl. Acad. Sci. U.S.A.

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“…Manchuriophycus Endo and Rhynsonetron Hofmann are two such examples (see Glaessner, 1969;Hofmann, 1971;Hantzschel, 1975). Plummer and Gostin (1981) have provided a review of shrinkage cracks and have discussed in detail the origin and morphology of synaeresis structures.…”

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confidence: 99%

Nonmarine Paleodictyon from the Carboniferous Albert Formation of southern New Brunswick

Pickerill

1990

atgeol

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The ichnogenus Paleodictyon is documented from the Carboniferous (Mississippian -late Toumaisean) nonmarine Albert Formation of southern New Brunswick. This occurrence represents only the second formal recording of the ichnotaxon in a nonmarine setting, as elsewhere Paleodictyon is almost universally a deep-water flysch trace fossil, rarely a shallow marine neritic form. In the Albert Formation Paleodictyon is restricted to strata deposited in a freshwater shallow lacustrine environment and it occurs in association with the ichnotaxa Cochlichnus anguineus, Gordia marina, Helminthopsis tenuis, Palaeophycus striatus, Palaeophycus tubularis and Planolites. Vermiform organisms, possibly annelids, are suggested to have been potential producers of these nonmarine Paleodictyon that probably formed as a result of the regular intersection of the same or different simple burrow systems. [Traduit par le journal]

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“…The other mode of preservation of late Precambrian forms is as trace fossils-markings made by animal activities (15)(16)(17). Some traces are of winding, rather featureless, trails, but others display transverse rugae and contain pellets that can be interpreted as offecal origin.…”

Section: Appearance Of Phyla In the Fossil Recordmentioning

confidence: 99%

Late Precambrian bilaterians: grades and clades.

Valentine

1994

Proc. Natl. Acad. Sci. U.S.A.

101

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A broad variety of body plans and subplans appear during a period of perhaps 8 million years (my) within the Early Cambrian, an unequaled explosion of morphological novelty, the ancestral l es represented chiefly or entirely by trace fossils. Evidence from the fossil record can be combined with that from molecular phylogenetic trees to suggest that the last common ancestor of(i) protostomes and deuterostomes was a roundish worm with a blood vascular system and (ii) of arthropods and annelids was similar, with a hydrostatic hemocoed; these forms are probably among trace makers of the late Precambrian. Cell-phenotype numbers in living phyla, and a model of cell-phenotype number increase, suggest an origin of metazoans near 600 my ago, followed by a passive rise in body-plan complexity. Living phyla appearing during the Cambrian explosion have a Hox/HOM gene cluster, implying its presence in the common ancestral trace makers. The explosion required a repatterning of gene expression that mediated the development ofnovel body plans but evidently did not require an important, abrupt increase in genomic or morphologic complexity.

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Trace Fossils From the Precambrian and Basal Cambrian

Cited by 177 publications

References 21 publications

Pellet microfossils: Possible evidence for metazoan life in Early Proterozoic time

Pellet microfossils: Possible evidence for metazoan life in Early Proterozoic time

Nonmarine Paleodictyon from the Carboniferous Albert Formation of southern New Brunswick

Late Precambrian bilaterians: grades and clades.

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