Invertebrate Zoology ZOOL 3104 Burgess Shale How are

Invertebrate Zoology – ZOOL 3104

Burgess Shale

How are fossils made? • Animal is buried (dead or alive) – Mud, silt, volcanic ash, or sand • Fossils could also be frozen in ice, mummified in hot or cold deserts, or preserved in tar • Usually, all of a living thing’s soft parts decay, leaving only the hard parts

How are fossils made II • Replacement: the minerals replace, molecule by molecule, the hard parts or the remains • Permineralization: minerals fill in the spaces of the hard parts of the remains

Burgess Shale • Made famous to the general public by Stephen Jay Gould. 1989. Wonderful Life: The Burgess Shale and the Nature of History

Burgess Shale • Shale is a sedimentary rock formed by the deposition of successive layers of clay.

Burgess Shale • Shale is a sedimentary rock formed by the deposition of successive layers of clay. • Located in Yoho National Park in the Rocky Mountains, near Field, British Columbia, Canada.

Burgess Shale • Shale is a sedimentary rock formed by the deposition of successive layers of clay. • Located in Yoho National Park in the Rocky Mountains, near Field, British Columbia, Canada. • Cambrian rock formation over 500 million years.

Burgess Shale • Shale is a sedimentary rock formed by the deposition of successive layers of clay. • Located in Yoho National Park in the Rocky Mountains, near Field, British Columbia, Canada. • Cambrian rock formation over 500 million years. • So, what is so special about it?

A unique place • Exceptional preservation of soft bodied marine invertebrates. • Over 65, 000 fossil specimens of 120 species from the Burgess Shale are housed at the Smithsonian.

Burgess Shale

How preservation works? • Good preservation indicates deposition in anoxic conditions

How preservation works? • Good preservation indicates deposition in anoxic conditions • Many delicate details of soft part anatomy are preserved. (Legs and gills of trilobites, etc. )

How preservation works? • Good preservation indicates deposition in anoxic conditions • Many delicate details of soft part anatomy are preserved. (Legs and gills of trilobites, etc. ) • Swept off an adjacent, well-oxygenated carbonate platform by turbidity currents, and killed and protected from decay in anoxic water

http: //burgess-shale. rom. on. ca/en/seaodyssey/catastrophic-burial. php

The initial discovery • Charles D. Walcott (1909) • Secretary of the Smithsonian Institution (1850 -1927)

Charles D. Walcott

The Animals • Mud dwellers, filter feeders • Strollers, walkers and crawlers • Swimmers and floaters

Filter Feeders • P: Porifera

Filter Feeders • P: Echinodermata: C: Crinoidea

Mud Dwellers: • C: Polychaeta (P: Annelida)

Strollers, walkers and crawlers • P: Onychophora

Hallucigenia sparsa an Onychophoran from the Burgess Shale deposits of Canada

Strollers, walkers and crawlers • Unknown phylum Wiwaxia

Strollers, walkers and crawlers • P: Arthropods

Swimmers and floaters • P: Arthropoda: SP: Trilobites

Swimmers and floaters • P: Ctenophora, and Cnidaria

Weird Creature Award • P: Arthropoda

Weird Creature Award

Weird Creature Award • Anomalocaris over 12 inches long!

The world’s first known chordate • Pikaia

The Big Picture • Fossilization usually takes place only of hard parts • The Burgess Shale is unique in that it fossilized soft tissues • Many creatures fossilized in the shale are extinct and were truly unique.