One Hundred Years of Burgess Shale Arthropods  

Burgess Shale arthropods have played a pivotal role in our understanding of the Cambrian explosion over the last hundred years, sometimes even being taken as a proxy for the explosion as a whole.  However, their interpretation has changed dramatically over this period of time, with Walcott’s alleged shoehorning developing to modern cladistic classifications.  Complementary discoveries from China, Greenland and Sweden have illuminated the importance of the arthropods, but Burgess Shale arthropods remain central to any attempt to reconstruct early arthropod evolution.  Here I review progress in understanding these famous fossils, and show that a new degree of consensus has begun to emerge about their placement on the arthropod tree.  Nevertheless, reconstruction of the euarthropod crown group remains problematic, especially at its base; it seems that considerably more work will be required before the transition from stem group to crown group is fully understood.