Welcome to the MedLibrary.org Wikipedia Supplement on Burgess Shale -- Please Click to Return to Front Page

Burgess Shale
Marella, the most abundant Burgess Shale organism.
Type	Geological formation
Age	Middle Cambrian
Lithology
Primary	Shale
Location
Named for	Burgess Pass
Named by	Charles Doolittle Walcott
Region	Yoho National Park
Country	Canada

Further information: Burgess shale type fauna

The Burgess Shale is famous for the exceptional preservation of the fossils found within it, in which the soft parts are preserved. A Cambrian black shale formation, it crops out in the Canadian Rockies of British Columbia, Canada. It is in Yoho National Park, near the town of Field and is named after Burgess Pass.

Contents 1 History and significance 2 Taphonomy and diagenesis 3 Biota 4 See also 5 References 6 Further reading 7 Sources

History and significance

The Burgess Shale was discovered by Charles Walcott in 1909 while vacationing with his family. He returned in 1910 with his sons to work the quarry. The significance of the finds was not realised at the time of discovery; the trilobites found dated the fossils to the Middle Cambrian period, and Charles Walcott simply placed the unusual new species within the phyla known to exist during that period, a process Stephen Jay Gould dubbed "shoehorning" in his book about the Burgess Shale, Wonderful Life (1989). A reinvestigation of the fossils in the 1980s by Harry Blackmore Whittington, Derek Briggs, and Simon Conway Morris of the University of Cambridge, however, revealed that the fauna represented were much more diverse and unusual than Walcott had recognized. Indeed, many of the animals present had bizarre anatomical features and only the sketchiest resemblance to other known animals. Examples include Opabinia with five eyes and a snout like a vacuum cleaner hose; Aysheaia, which bears an extraordinary resemblance to a minor modern phylum — the Onychophora; Nectocaris, which is apparently either a crustacean with fins or a vertebrate with a shell; and Hallucigenia, which was originally reconstructed as walking on bilaterally symmetrical spines. Conway Morris now reconstructs it as another lobopod, with the spines on its back. Several poorly understood fossils were found to be body parts of a large predatory organism known as Anomalocaris. More recent (late 1990s) work by Derek Briggs and Richard Fortey has placed many of the "peculiar" Burgess Shale fossils as stem groups to the arthropoda, but many animals such as Amiskwia resist attempts to decipher their relationships to other groups.

Gould's Wonderful Life, published in 1989, popularized the Burgess Shale fossils. Gould suggests that the extraordinary diversity of the fossils indicate that life forms at the time were much more diverse than those that survive today and that many of the unique lineages were evolutionary experiments that became extinct. He suggests that this interpretation supports his hypothesis of evolution by punctuated equilibrium. Gould's interpretation of the diversity of Cambrian fauna relied heavily on Simon Conway Morris' reinterpretation of Charles Walcott's original publications. Morris would later write in his book The Crucible of Creation: The Burgess Shale and the Rise of Animals that almost all the Cambrian fauna could be classified into modern day phyla. The conflict between Gould and Morris came to a head when both published there respective opinions in a debate column of Natural History magazine^[1].

The diversity and exotic nature of the Burgess fauna (Middle Cambrian, 505 mya^[2]) has caused a great deal of controversy in paleontology with regard to the reasons for and nature of the preceding period in the history of life that has come to be called the Cambrian Explosion.

Further investigations showed that the Burgess Shale extends for many miles in isolated outcrops and the various faunas are preserved in different places. The deposits appear to represent small areas of muddy ocean bottom that — from time to time — slid down the face of a limestone cliff, turbidite flows by gravity currents, carrying their fauna and anything unfortunate enough to be swimming by into oxygen-poor waters in the depths. Six distinct faunal zones have been identified in the Burgess Shale. Now that scientists know what to look for, similar deposits have been identified elsewhere with similar faunas. The most important, similar deposits are even older turbidite flow deposits created in much the same way as the Burgess shales in Yunnan Province, China. These Maotianshan shales contain fauna quite similar to the Burgess.

Due to its location within Yoho National Park, the shale is part of a UNESCO World Heritage Site, specifically, the Canadian Rocky Mountain Parks. Subsequent exploration has found exposures of the shale over a front of several dozen kilometers and has identified at least six fossiliferous lagerstätten within the formation.

Taphonomy and diagenesis

Further information: Burgess shale type preservation

Please expand this section^{[3][4][5][6][7][8]}

Biota

Main article: Burgess shale type biota

Please expand this section - see talk page

See also

• Body form
• Fossil parks — protected fossiliferous sites world-wide
• Invertebrate paleontology
• History of invertebrate paleozoology
• List of fossil sites (with link directory)
• List of notable fossils
• Micropaleontology
• Paleobiology
• Paleozoology
• Treatise on Invertebrate Paleontology (50 volumes; 1953 to 2006, and continuing)
• Science and technology in Canada

References

Further reading

• Simon Conway Morris, The Crucible of Creation: The Burgess Shale and the Rise of Animals, Oxford University Press, Oxford, 1998 (paperback 1999) ISBN 0-19-850197-8 (hbk), ISBN 0-19-286202-2 (pbk)
• Richard Fortey, Trilobite: Eyewitness to Evolution, Flamingo, 2001. ISBN 0-00-655138-6
• Stephen Jay Gould, Wonderful Life: Burgess Shale and the Nature of History, Vintage, 2000. ISBN 0-09-927345-4
• Derek E. G. Briggs, Douglas H. Erwin, & Frederick J. Collier, The Fossils of the Burgess Shale, Smithsonian, 1994. ISBN1-56098-364-7

Sources

• The Burgess Shale Geoscience Foundation — official website
• The Burgess Shale — Evolution's Big Bang — Burke Museum of Natural History and Culture web pages resourcing an exhibition devoted to the Burgess Shale
• Burgess Shale Fossils
• The Cambrian Explosion — BBC Radio 4 broadcast, In Our Time, 17 February 2005, hosted by Melvyn Bragg (includes links to resource pages)
• Stephen Jay Gould (1989), Wonderful Life: The Burgess Shale and the Nature of History (New York: W. W. Norton). This best-seller critiques Charles Doolittle Walcott's discovery; and it provides over two dozen illustrations of the metazoans found.
• Paleobiology Database The Burgess Shale (skeletonized fauna), Stephen Fm., British Columbia, Canada: St Davids, British Columbia
• Paleobiology Database Hanburia gloriosa, Phyllopod Bed, Burgess Shale, Canada — Whittington 1998: St Davids — Merioneth, British Columbia
• Smithsonian Museum
• Species index from the Smithsonian Institution

v • d • e World Heritage Sites in Canada Canada Canadian Rocky Mountain Parks · Dinosaur Provincial Park · Gros Morne · Head-Smashed-In Buffalo Jump · Joggins Fossil Cliffs · L'Anse aux Meadows · Old Town Lunenburg · Miguasha · Nahanni · Old Quebec · Rideau Canal · SGaang Gwaay · Wood Buffalo Canada / USA Kluane-Wrangell-St. Elias-Glacier Bay-Tatshenshini-Alsek · Waterton-Glacier International Peace Park

Coordinates: 51°26′18″N 116°28′36″W / 51.43833, -116.47667

Wikipedia content modification information:

• This page was last modified on 29 August 2008, at 21:57.

Wikipedia Authorship and Review

Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.

Wikipedia Usage Guidelines

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Burgess Shale".

The URL for this specific entry is:

• http://medlibrary.org/medwiki/Burgess_Shale

All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.