The Nature Of Preservation : Macrofossils And Ichnofossils

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Macrofossils and ichnofossils can be used to generate reconstructions of ancient environments based on the nature of preservation. Both of these allow us to interpret different aspects of the environment the fossils were preserved in and its controls, however advantages and disadvantages of each must be considered so that the data collected is treated with the appropriate caution. Macrofossils, ranging from bones to shells, with exceptional preservation allowing for the analysis of soft tissues, focuses on the analysis of the organism itself to interpret the conditions that it lived in, whereas ichnofossils, or trace fossils as they are more commonly known, provide a more useful indicator as to how the organism lived in its environment.…show more content…
It is unusual that more than 50% of a living community consists of organisms with bio-mineralised skeletons (Brenchley & Harper, 1998), with soft bodied organisms such as algae, and many others at the base of the food chain lacking sufficient preservation potential, therefore skewing reconstructed trophic models with their absence. Amongst those fauna that have been preserved, many processes during subsequent geological events can affect the final assemblage – the most important of which being chemical dissolution (Brenchley & Harper, 1998). When considering small shelly fauna in marine environments, in most cases it is likely that preservation will favour older, more developed organisms, as these will often be of sufficient size and have grown the appropriate body parts to be preserved. Nevertheless, the sizes that are preserved can sometimes be indicative of the environmental conditions during the organisms’ lifetimes –the range of sizes in the environment can be used to determine whether there were any limiting controls on growth when comparing to datasets from control environments. When the situation arises that the environment in which communities are living changes, this can also affect the fossil record. Most likely to occur in nearshore marine environments, this involves the replacement of
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