Trace fossils

Trace fossils are evidence of an organism, but are not part of a plant or animal. Examples are footprints that are preserved in hardened mud, excrement (poop), nests, or filled-in channels in mud where an animal lived. 

The feces or droppings of many animals have been utilized in a variety of ways for thousands of years. While manure rarely appears in museum collections, it should still be considered as a potential element in certain collections. Dried manure may be a normal component of natural history collections. And animal droppings have been occasionally utilized as a medium in modem art. Coprolites, which are fossilized droppings, are trace fossils and may be found in most paleontological collections. 

The first stage of the Lower Cambrian is known today as Manykayan (trace fossils), after which come the Pommotian (small shelly fossils), the Atdabanian (trilobites), and the Botomian, while the other two stages of the period are still known with the generic names of Middle and Upper Cambrian (Figure 7.1). 

In the last twenty years, in conclusion, paleontology has discovered that in Cambrian times there have been not one but three different explosions ofanimallife one documented by trace fossils, a second which left behind small shelly fossils, and finally the classical explosion that was dominated by trilobites. It must also be added that Cambrian life was preceded by the so-called Ediacara fauna, a vast assembly of soft-bodied animals (almost all with radial symmetry). Many scholars now regard them as a failed evolutionary experiment, while others believe that they may have left modified descendants (Figure 7.1). 

Bromley, R. (1970). Borings as trace fossils and Entobio cretacea Portlock, as an example. In Trace Fossils, eds. T. P. Crimes J. C. Harper. Liverpool, UK Seel House Press, pp. 49-90. 

Golubic, S., Perkins, R. D. Lukas, K. J. (1975). Boring micro-organisms and microborings in carbonate substrates. In The Study of Trace Fossils, ed. R. W. Frey. Berlin Springer-Verlag, pp. 229-59. 

Genise J. E., Mangano M. G., Buatois L. A., Laza J. H., and Verde M. (2000) Insect trace fossil associations in paleosols the Coprinisphaera ichnofacies. Palaios 15, 49-64. 

Trewin N. H. and McNamara K. J. (1995) Arthropods invade the land trace fossils and palaeoenvironments of the Tumblagooda Sandstone ( Late Silurian) of Kalbarri, Western Australia. Roy. Soc. Edinburgh, Earth Sci. Trans. 85, 117-210. 

In addition to body fossils, paleoecologists study trace fossils. These are things like footprints, gopher burrows, or worm trails preserved in sediments. Trace fossils indicate the behavior of the organism that made the trace and physical factors about the environment. For example, a trail of dinosaur footprints preserved in stream bed sediments provides evidence of how fast the dinosaur was moving, based on spacing of the prints. The depth of the footprints suggests how soft the sediments were, and hence, whether the stream bed was dry at the time the dinosaur traversed it. 

Crimes, T.P. and Harper, J.C. (Editors), 1970. Trace Fossils, Geological Journal Special Issue, No. 3, 547 pp. 

Frey, R.W. (Editor), 1975. The Study of Trace Fossils. Springer, Berlin, 562 pp. 

Various species of fungi are encountered in mollusc or barnacle shells where they exploit the orgemic matter laid down by the animal between the crystallites of CaCOs (see e.g. Plate 8 of Schneider, 1976). Several of these fungi have been described by Zebrowski (1936) and Porter and Zebrowski (1937) only on the basis of excavations and thus must be considered trace fossil taxa, since the living organisms have not been described. 

Bromley, W.G., 1970. Borings as trace fossils and Entobia cretacea Portlock as an example. In T.P. Crimes and J.C. Harper (Editors) Trace fossils. Geol. J., Spec. Issue, 3 49-90. 

The rocks of the Bowers Supergroup are structurally deformed but only slightly metamorphosed (preh-nite-pumpellyite or lowermost greenschist facies) and their ages are indicated by fossils such as acritarchs, trace fossils, as well as trilobites, brachiopods, and mollusks (Laird et al. 1972, 1974 Dow and Neall 1974 Shergold et al. 1976 Andrews and Laird 1976 Cooper et al. 1976,1982). 

Schmidt and Ford (1969) mentioned that a thin layer of marble in the Mt. Walcott Formation contains stromatolites. However, Storey and Macdonald (1987) and Pankhurst et al. (1988) later stated that these stro-matohtes are actually composed of interlaminated calcareous siltstone and limestone that underwent soft-sediment deformation. The same authors did find abundant echinoderm plates and sponge spicules similar to Protospongia fenestrata which occurs in the Middle Cambrian Nelson Limestone of the Pensacola Mountains (Weber and Fedorov 1980, 1981). The Mt. Walcott Formation also contains trace fossils (Planolites and Chondrites). Although Planolites has been found in rocks that are 1,000 milhon years old, the earhest appearance of Chondrites is in rocks of Cambrian age. Therefore, Pankhurst et al. (1988) concluded that the paleontological evidence supports a Phanerozoic age for the Mt. Walcott Formation, whereas Schmidt and Ford (1969) had previonsly assigned it a probable Neoproterozoic age. 

The Beacon rocks in Wright and Taylor valley contain a variety of trace fossils described by Vialov (1962), Webb (1963), Webby (1968), Gevers et al. (1971),... 

Gevers and Twomey (1982). The presence of plant and trace fossils in the Beacon rocks of southern Victoria Land suggests that the climate at the time of deposition of the Beacon sandstones was temperate and supported an abundant flora and fauna even though conditions at certain times and in certain places in Gondwana were arid as suggested by the presence of mud-cracked surfaces of shale layers and calcite concretions. The geologic... 

The sandstones of the Alexandra Formation, like those of Beacon Heights Orthoquartzite and the Hatherton Sandstone, contain only a few trace fossils. Nevertheless, the Devonian age of the Alexandra Formation is indicated by its correlation to the Beacon Heights Orthoquartzite which contains impressions of lycopod stems (Plumstead 1962), while the overlying Aztec Siltstone contains abundant fossil fish and plant microfossils which constrain a Devonian age (McKelvey et al. 1970, 1972 Helby and McElroy 1969). 

The Buckeye Tillite grades up-section into the Weaver Formadon, the lower part of which is composed of shale with animal trails and ice-rafted pebbles. The middle part consists of interbedded siltstone and shale containing trace fossils. The upper part is a massive sandstone topped by a thin shale bed. The sandstone is characterized by the presence of animal burrows while the shale contains abundant Glossopteris leaves. 

During the 1979/80 field season a group of New Zealand geologists led by M.A. Bradshaw returned to the Ohio Range in order to examine more closely the environment of deposition of the Early Devonian Horlick Formation. The group confirmed that brachiopods, mollusks, trilobites, crinoids, fish bones, and trace fossils occur at all levels in this formation and that it was indeed deposited in a marine environment in contrast to most sedimentary rocks of the Beacon Supergroup which are predominantly of non-marine origin (Bradshaw and McCartan 1983). 

Bradshaw MA (1981) Palaeoenvironmental interpretations and systematics of Devonian trace fossils from the Taylor Group (lower Beacon Supergroup), Antarctica. New Zealand J Geol Geophys 24 615-652... 

Gevers TW, Twomey A (1982) Trace fossils and their environments in Devonian (SUutian) lower Beacon strata in the Asgard Range, Victoria Land, Antarctica. In Craddock C (ed) Antarctic geoscience. University of Wisconsin Press, Madison, WI, pp 639-647... 

The average values on the PDB scale of calcite in samples of carbonate rocks from the Beacon Supergroup in the central Transantarctic Mountains in Table 11.2 range from -24.5 %o (Alexandra Formation) to -28.4%o (Buckley Formation). The evident depletion in relative to oxygen in marine calcite is strong evidence that these calcites were not precipitated from seawater. This conclusion applies even to the calcite in the Alexandra Formation which contains trace fossils that indicate that the rocks of this formation were deposited... 

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