PhD: Small Carbonaceous Fossil Assemblages in the Burgess Shale

The early stages of the Cambrian witnessed an unmatched period of ecological escalation, culminating in the establishment of biological communities with a fundamentally modern constitution. Such assemblages are briefly visible in sites of exceptional soft tissue preservation such as the mid-Cambrian Burgess Shale — but such sites offer a restricted sampling of palaeoenvironments and time, and largely post-date the period of the Cambrian ‘explosion’ itself.

An alternative, fundamentally more representative rendering of early Cambrian life is provided by assemblages of small carbonaceous fossils (SCF)—which represent the teeth, scales, claws and other robust components of pioneering Cambrian organisms. SCF assemblages offer to provide a more comprehensive perspective on the gradual rise and diversification of Cambrian communities — but are likely subject to a suite of taphonomic biases.

Understanding the correspondence between SCF assemblages and original animal communities is essential to tracking the rate and pattern of evolution through the period of the Cambrian explosion. The Burgess Shale offers a unique opportunity to link SCF assemblages to bed-by-bed level surveys of representative macrofossil communities.

This reconciliation of microfossil and macrofossil assemblages will yield a new understanding of the preservational biases associated with each taphonomic mode, and establish approaches to inferring original communities from fossil assemblages.

Taken together, this project will unlock the SCF record as a chronicle of early Cambrian evolution, bringing a new perspective on the increasing complexity of animal assemblages through the pivotal period of the Cambrian explosion.