Burgess Shale

In 1909, Charles Walcott discovered the renowned Burgess Shale in the Canadian Rockies in an interesting way. His wife’s horse had tripped over a rock on the trail below the rock layers that contain fossils. Walcott split the rock and found well preserved fossils. Walcott walked up the incline and found the Burgess Shale, home to a variety of fossils. Over 60,000 specimens were quarried in the following years after this discovery. Later on, it was thought that most of the discoveries had been weeded out and that there were few fossils left to be found. However, a recent report indicated a new site at Marble Canyon and yielded 3000 specimens in only two weeks in 2012. Remarkably, some of the fossils had preserved tissues such as internal organs and traces of the nervous system which provide more clues than the remnants of just the harder parts of an organism. These fossils were dated to be from the Cambrian period and range from a a variety of sizes and shapes, speaking to the complex existence of life that existed during the Cambrian period. Later on, well preserved Cambrian fossils have been found around the world, namely the Cambrian Chengjiang localities of China. From the clues given from the fossils found, paleontologists can determine who were the progenitors of many of the organisms that we know today. Additionally, the fossils are proofs of the diversification that followed the Cambrian Explosion. The diversity and density of fossils found at this site has been one of the most amazing finds and has contributed to the field of paleontology greatly.

Charles Walcott

How were the tissues preserved?

Soft tissue is preserved due to the inhibition of decay and prevention of scavenging by other organisms. However, these factors are not unique to Cambrian environments, so research has shown that Cambrian seawater was the main reason as to how the living tissues were preserved. The low concentrations of sulfate reduced the oxidants available for bacteria to cause decay. The high alkalinity of the water allowed earlier precipitation of carbonate, allowing preservation. Hence, the ideal place for tissue preservation was regions of the oceans where there were fine sediments deposited in a low oxygen level location. As a result, the fossils in the Burgess Shale have given us a lot of information on the origin and evolution of many major animal groups.

File:Cambrian Trilobite Olenoides Mt. Stephen.jpg

Olenoides, Cambrian Trilobite that was found at the Burgess Shale

Works Cited
Briggs, Derek E.g. “Paleontology: A New Burgess Shale Fauna.” Current Biology 24.10 (2014): n. pag. Web.

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