Cambrian Explosion in Full Bloom
James W. Hagadorn
THE MIDDLE CAMBRIAN BURGESS SHALE IS ONE OF THE world's best-known and best-studied fossil deposits. The story of the discovery of its fauna is a famous part of paleontological lore. While searching in 1909 for trilobites in the Burgess Shale Formation of the Canadian Rockies, Charles Walcott discovered a remarkable “phyllopod crustacean” on a shale slab (Yochelson 1967). Further searching revealed a diverse suite of soft-bodied fossils that would later be described as algae, sponges, cnidarians, ctenophores, brachiopods, hyoliths, priapulids, annelids, onychophorans, arthropods, echinoderms, hemichordates, chordates, cirripeds, and a variety of problematica. Many of these fossils came from a single horizon, in a lens of shale 2 to 3 m thick, that Walcott called the Phyllopod (leaf-foot) Bed. Subsequent collecting at and near this site by research teams led by Walcott, P. E. Raymond, H. B. Whittington, and D. Collins has yielded over 75,000 soft-bodied fossils, most of which are housed at the Smithsonian Institution in Washington, D.C., and the Royal Ontario Museum (ROM) in Toronto.
Although interest in the Burgess Shale fauna has waxed and waned since its discovery, its importance has inspired work on other Lagerstätten and helped galvanize the paleontological community's attention on soft-bodied deposits in general. For example, work on the Burgess Shale has stimulated work on the older Chengjiang fauna (Chapter 3), as well as a number of other Burgess Shale–type localities from around the world (Chapter 5).
In the first descriptions of the Burgess fauna, Walcott placed most of the new taxa (over 110 species) within existing taxonomic groups.