Micro-Burgess Shales  

Burgess Shale-type fossils are best known as macroscopic compressions on bedding surfaces, but they can also be extracted by dissolving away the shale matrix with hydrofluoric acid (HF). Most of these isolated organic-walled fossils are microscopic, but readily identifiable as the disarticulated remains of larger organisms – both animals and “plants”. Some of these can be associated with known macrofossils and shed important new light on their (micro) constructional anatomy and phylogenetic relationships (e.g., Wiwaxia, hyolithids, chancelloriids). Others have yet to reveal their overall form, but can be classified on the basis of diagnostic characters, including the oldest documented occurrences of sophisticated crustacean and molluscan feeding apparatuses.  Still others remain entirely problematic, but promise a substantially improved account of Early-Middle Cambrian palaeobiology.  Perhaps most significantly, these microscopic biotas are proving to be far more widespread than their elusive macroscopic counterparts, with a potential for greatly increasing the stratigraphic and palaeogeographic resolution of Burgess Shale-type fossils.  In this presentation, we will report on material recovered from the Mahto Fm.  (Early Cambrian, Alberta), Forteau Fm.  (Early Cambrian, Newfoundland), Mount Cap Fm.  (Early-Middle Cambrian, NWT), Burgess Shale Fm.  (Middle Cambrian, British Columbia), Kaili Fm.  (Middle Cambrian, South China), Pika Fm.  (late Middle Cambrian, Alberta) and Earlie Fm.  (Middle-?Late Cambrian, Saskatchewan).