The significance of the fauna of the Burgess Shale, Middle Cambrian, British Columbia
Abstract
The fauna includes about 150 species of 119 genera, one-third had mineralised hard parts, the remaining two-thirds embraces at least 30 genera of arthropods, together with fewer kinds of worms, coelenterates, lophophorates, hemichordates, the oldest known chordate, and animals of unknown affinities. The stratigraphy shows that this community lived at a depth of at least 100 m, on the edge of a continent, and was not peculiar to an isolated habitat; it may be more representative of Cambrian marine communities than assemblages consisting only of hard parts. Genera rarely include more than one species, and are separated one from one another by wide morphological gaps; many are difficult to fit into an existing order, class or phylum. The fauna shows that the early evolutionary diversification of Metazoa in the marine environment was along many parallel, distinct lines, in the absence of the more intensive later competition. The major taxa of today were not defined, they were clarified by subsequent evolution and extinction. If the evolution of metazoans was taking place independently on separate Cambrian continents, then parallelism may have been great and extended back to the beginnings of metazoans.
- Publication:
-
Proceedings of the Geologists' Association
- Pub Date:
- 1980
- DOI:
- 10.1016/S0016-7878(80)80034-4
- Bibcode:
- 1980PrGA...91..127W