The Burgess Shale Fauna

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Table of Contents

The Burgess Shale Fauna 3
Introduction 3
History of Discovery 3
Preservation Bias 4
Major Fossils 4
Concluding remarks: 7
References: 8 The Burgess Shale Fauna

The Burgess Shale Fauna is a fauna that was constructed based on a group of fossils that were initially found, in the Burgess Shale area in the Canadian Rockies (Gould, 1989). They are a very important group of fossils as “modern multicellular animals make their first unprotected appearance in the fossil record some 570 million years ago” through this group (Gould, 1989, pp. 24). Moreover the Burgess Shales are known to have preserved the soft parts of animals enabling us to get a
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Burgess-type fauna in the Canadian Rockies probably lived in shallow-water, mud-banks that were well lit and aerated. Such an environment would naturally lead to a fast rate of decomposition (Gould, 1989). What led to the preservation of the soft-bodied fauna is relatively unknown (Royal Ontario Museum, 2011). However one dominating theory is that fine-grained sediments were occasionally deposited in the area burying both live and dead animals. The buried animals were then probably left in an anoxic environment inhibiting bacteria and scavengers from destroying them. Another hypothesis is that the presence of clay in the sediments might have inhibited the organisms’ decay by bacteria (Royal Ontario Museum, 2011). Thus probably only the very soft tissues decomposed resulting in the flattening of the organisms’ body and the preservation of the compacted fossils we find today (Royal Ontario Museum, 2011).
Major Fossils
More than half of the Burgess Shale fauna “burrowed in or lived freely on the sea-floor and most of these were deposit feeders” (Cowen et al., 2006, pp. 58). The most

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