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Trace Fossils

Trace Fossils. ichnofossils. Tracks and Trails . These features result from organisms moving across the sediment as they walk, crawl, or drag their body parts through the sediment. Burrow Marks.

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Trace Fossils

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  1. Trace Fossils ichnofossils

  2. Tracks and Trails • These features result from organisms moving across the sediment as they walk, crawl, or drag their body parts through the sediment.

  3. Burrow Marks • Any organism that burrows into soft sediment can disturb the sediment and destroy many of the structures • If burrowing is not extensive, the holes made by such organisms can later become filled with water that deposits new sediment in the holes.  • Such burrow marks can be excellent top and bottom indicators.

  4. TRACE FOSSILS • Biogenic sedimentary structures are formed through the activities of animals and plants and vary widely from indistinct disruptions of bedding/laminations (bioturbation) to discrete trace fossils (ichnofossils). • The term ichnofabric refers to the sediment’s texture and internal structure arising from bioturbation and a bioturbation index [from 0 (no disruption) to 6 (complete disruption)] is often used to describe the degree of disruption. • Trace fossils are best considered in terms of their mode of formation: crawling, grazing and resting (on bedding surfaces) and feeding and dwelling (within the beds).

  5. TRACE FOSSILS • ♦ crawling traces: trails, uncomplicated pattern; linear or sinuous. • ♦ grazing traces: more complicated surface trails, symmetrical or ordered pattern; coiled, radial, meandering. • ♦ resting traces: impression of where animal rested during life (but not a fossil mold). • ♦ dwelling structures: simple to complex burrow systems but without suggestion of systematic working of sediment; burrows can be lined or pelleted. • ♦ feeding structures: simple to complex burrow systems commonly with well-organised and defined branching pattern indicating systematic reworking of sediment.

  6. CRUZIANA RUSOPHYCUS DIPLICHNITES

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