Friday, April 29, 2011

Burgess Shale

The Burgess Shale is an amazing deposit. Since its discovery at the turn of the last century, it has been our window into an amazing explosion of life during the Late Cambrian. Organisms living in the equatorial waters of what is now British Columbia were periodically buried in mud-rich blankets of sediment coming off the nearby reef (the Cathedral Escarpment). Anoxic conditions and rapid burial led to the preservation of soft parts.

My personal favorite critter from the Burgess is Wiwaxia. How can  you not love a creature that looks like a pinecone with spikes coming out of its back? Debate continues as to where this creature can be classified. It has been variously assigned to Annelida, Mollusca, and Ecdysozoa (see Eibye-Jacobsen, 2004 for a discussion of Wiwaxia's phylogenetic position).

Wiwaxia (scale in mm) Peabody Museum of Natural History

To aid in visualizing this critter in life, here's a recreation from the Smithsonian's site:

And Wiwaxia is just one of the many strange and wonderful creatures who inhabited the seas at this point in our world's history.  Check out the Smithsonian's site (A Burgess Shale Sampler) for more amazing organisms.

The Burgess Shale was made a UNESCO World Heritage site in 1981. In 1990 it was featured in Stephen Jay Gould's "Wonderful Life." National Geographic made a movie about it. It has its own website: Burgess Shale Geoscience Foundation. It has its own toys (available through the Royal Ontario Museum). It even had its own beer, but geologists being what they are, the stock quickly ran out. This kind of broad acclaim is generally reserved for dinosaurs and their ilk, but it simply shows how amazing and interesting the Burgess Shale is.

Eibye-Jacobsen, D. 2004. "A reevaluation of Wiwaxia and the polychaetes of the Burgess Shale." Lethaia. vol. 37, no. 3. pp. 317-335.

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