I use a combination of novel and published fossil occurrence data to investigate ecological changes in marine paleocommunities during intense ecosystem changes in the Ordovician Period (~487–443 million years ago) of Earth’s history. My work focuses on trilobites, an extinct group of marine arthropods, and how they distributed themselves across different habitat types during the prolonged ecosystem restructuring of the Ordovician Radiation, as well as their response to the more abrupt end-Ordovician mass extinction. The fossil record contains many examples of climate change-induced mass extinction events, but only a few are associated with the transition from an “icehouse” to an “ice-free” world. The end-Ordovician event is one such instance and therefore can provide useful context for the ongoing biodiversity crisis and associated ecosystem changes.

My research has two primary aims. First, I am investigating the reorganization of trilobite communities across depth-related habitat types in response to the climate change-driven end-Ordovician mass extinction, which eliminated over 50% of global trilobite diversity at higher taxonomic levels. Within-habitat (alpha) species diversity remained unaffected by the extinction event, which suggests that a dissimilarity component of diversity may have been altered. I am investigating the between-habitat (beta) diversity response of trilobites to determine if local (alpha) diversity was maintained by reducing taxonomic dissimilarity among habitat types. Additionally, I am examining the habitat associations of taxonomic lineages that survived, and did not survive, the extinction event to assess if habitat preference, or changes to it over time, was linked to extinction likelihood.

Initial results from Laurentia (most of present-day North America) support a decline in between-habitat dissimilarity following the end-Ordovician mass extinction. This mechanism appears to have at least partially maintained local diversities, potentially buffering against wider ecosystem changes in the wake of the extinction. Ongoing research will determine if this reorganization was unique to Laurentia and if the pattern holds up to additional examination.