BURGESS SHALE

Kelly LekanNovember 19, 2007

GEO 401

LOCATION

• British Columbia, Canada

• Yoho National Park

GEOLOGY• Cambrian period

– ~505 million years ago• Once located on the

Western edge of Laurentia– Was near the equator– Environment was a

warm, shallow marine environment where light could easily penetrate the area.

GEOLOGY

• Found within the Stephen Formation– Located between Mount Wapta and Mount

Field.• Two major quarries

– Walcott quarry (Named for founder of the Burgess Shale Charles P. Walcott)

• Contains the Phyllopod Bed• Most famous fossil collecting site

– Raymond quarry

WALCOTT QUARRY

PRESERVATION• Deposited in a deep-

water basin adjacent to an algae reef

• Turbidity flows and mudslides transported and buried the organisms– Anoxic environment– Rapid burial– Killed instantly– Not in life position

PALEONTOLOGY

• The best record we have of Cambrian animals– Most diverse and well-preserved fossil

localities– Soft body preservation

PALEONTOLOGY

• 60,000 unique fossils have been collected• 140 species• 119 genera• ‘Weird wonders’

PALEONTOLOGY• Dominated by arthropods• Sponges, worm-like phyla, brachiopods, echinoderms,

chordates, and mollusks• 13 different genera of trilobites• Diversity of life

– Benthic (lived in the substrates in the bottom of the ocean)– Active and passive suspension feeders, deposit feeders,

scavengers, active predators– Free swimmers and bottom dwellers

• Bottom dwellers moved by either burrowing or crawling• Microfossils

– Bacteria, protists, cyanobacteria, and dinoflagellates• Macroscopic algae

PALEONTOLOGY

• Well preserved exoskeletons, limbs, and infillings of the gut

• Soft tissue and muscles• Phyllopod Bed• Dark Stains

– Radioactive carbon

EVOLUTION

• Best record of Cambrian animals• Cambrian explosion

– 545-525 million years ago– Appearance of many new organisms– Soft bodied organisms

• ‘Taphonomic Window’– “Historical snapshot in the diversity of ancient

life”

SIGNIFICANCE

• Best record of Cambrian animals• Best record of soft body preservation• Evidence of Cambrian explosion• Evolution from pre-Cambrian life forms• Diversity of life

– Modes of life/adaptation– Body plans

REFERENCES AND IMAGES• HPVM: Hooper Virtual Paleontological Museum. Burgess Shale:

Hidden Treasure in the Canadian Rockies. http://park.org/Canada/Museum/burgessshale/tablen.html

• MacRae, Andrew. Burgess Shale Fossils. http://www.geo.ucalgary.ca/~macrae/Burgess_Shale/

• Rivera, Alexei A. Fossil Lagerstatten: Burgess Shale. Department of Earth Sciences. University of Bristol. http://palaeo.gly.bris.ac.uk/palaeofiles/lagerstatten/Burgess/biota.html.

• Smithsonian: National Museum of Natural History. The Burgess Shale: Strange Creatures – A Burgess Shale Fossil Sampler. http://paleobiology.si.edu/burgess/index.html

• Trilobites. Trilobites of the Burgess Shale, Canada. http://www.trilobites.info/Burgess.htm

• UCMP Berkeley. Localities of the Cambrian: The Burgess Shale. http://www.ucmp.berkeley.edu/cambrian/burgess.html.