505 - 485 Million Years Ago
Burgess Shale
The Burgess shale locality represents a window allowing us to see the full array of soft bodied organisms that were living 550 million years ago as well as those organisms with hard exoskeletons.
The single locality, high on a mountainside in Yoho National Park, was found accidentally in 1910 by Charles D. Walcott, who later became head of the U.S. Geological Survey. His horse apparently overturned a fossiliferous slab of shale and further examination revealed the locality. He returned for several years following, quarrying the locality and carrying material down to the base camp. Even today the location of the camp is pinpointed by the piles of shale that were sorted and split in the search for these fossils.
The fossils represent the primitive ancestors of nearly every class of arthropods together with many other groups (sponges, worms, algae, and a host of extinct forms of uncertain biological affinities). The fossils thus have enormous importance in geology and biology in the understanding of early metazoan evolution, particularly for the arthropods - the largest phylum existing today.
Why is there only one single locality within the outcrop belt of the Burgess Shale which has yielded such superb and unique fossils? Only in the last decade has regional mapping and restudy of the Burgess Shale revealed the presence of an ancient submarine escarpment. The Burgess Shale fossils were preserved in a small stagnant recess near the base of the 800 foot escarpment. Rapid burial in a low energy environment allowed the remarkable preservation of the soft parts of the organisms.
In 1982 the museum purchased a small diorama of Burgess Shale fossils from Chase Studio, Cedar Creek, Missouri. At the time they were building a display for the Smithsonian in Washington.
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Burgess Shale Fossils
This collection is from an expedition by the Royal Ontario Museum to the Burgess Shale formation in 1975. From the fossils gathered, several collections were made up and given to museums and universities for study of the world famous Burgess Shale fossil field. These specimens give us great insight into early evolution, and the progression into modern animal forms. More specimens and details to follow in 2013.
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