Research Interests

I am interested in the patterns and processes that underlie the generation of animal diversity. For most of my work, I use echinoderms (sea urchins, star fish, and their relatives) as a model system to address large-scale questions regarding patterns of diversification and extinction and to understand the molecular and genetic mechanisms that underlie animal diversity in the geological past and on the planet today. Most of my work is specimen-based, and museum collections form the basis of my primary data.

Macroevolutionary Patterns

Because of their excellent fossil record, sea urchins provide an ideal model group to examine the interplay of broad-scale changes in the Earth system and animal diversity. For much of my work, I use phylogenetic analyses to understand patterns of origination and extinction in various echinoderm groups. This work has provided into the pace and magnitude of diversification, and unraveled key morphological transitions underlying the evolution of the echinoderm body plan. In addition to larger scale analyses of diversification, the foundation of all paleobiological research is fossil specimens, and in order to increase the precision of large-scale macroevolutionary analyses, it is also important to generate novel data. As such, I undertake taxonomic and systematic research and describe new fossil faunas from around the world in order to produce a more finely calibrated understanding of ancient biodiversity.

Collaborators: Dr. Imran Rahman (Natural History Museum), Nicolás Mongiardino Koch (University of California, San Diego), Georgy Mirantsev (Paleontological Institute, Moscow)

Developmental Evolution

I am not only interested in macroevolutionary patterns and trends in organismal morphology, but also the molecular and genomic mechanisms that underlie evolutionary changes in animal body plans. I have utilized phylogenetic comparative approaches to understand the evolution of gene regulatory networks, and changes in gene expression that underpin morphological changes in echinoderm development. This work has involved molecular phylogenetics, fossil-calibrated divergence time estimation, and comparative analyses of gene expression. Recent work (funded by the Royal Society) has used assays of gene expression and protein localization, paired with comparative transcriptomics, to understand the differential mechanisms of skeletal growth in sea urchins.

Collaborators: Prof. Paola Oliveri (UCL), Dr. Eric Erkenbrack (Yale University), Dr. Ferdinand Marletaz (UCL)

Mass Extinction Events

Understanding the effects of mass extinction in the geological past provides a roadmap to mitigate the effects of current climatic change on the marine biosphere. Sea urchins underwent a massive evolutionary bottleneck during the Permian-Triassic mass extinction, and are an ideal model group to understand the effects of mass extinction on organismal diversity dynamics. Through recent and ongoing taxonomic and phylogenetic work, I have tried to better understand the pace and magnitude of sea urchin extinction. Beyond my work on sea urchins, I am interested in understanding the relationship of extinction and recovery dynamics over mass extinction events to climatic and environmental changes (e.g. anoxia, temperature) more generally. This interest extends to analysis of morphological trends over mass extinction intervals, such as morphological disparity and body size.

Collaborators: Dr. Elizabeth Petsios (Baylor University), Amanda Godbold (University of Southern California)

Taphonomy and Paleoecology

In order to understand data from the fossil record, it is essential to understand how and why fossils are distributed in time and space the way they are. Because of this, I am interested in the roles of taphonomy and paleoecology in influencing the spatial and temporal distribution of fossils. To understand the role of taphonomy and paleoecology in influencing the distribution of fossil echinoderms, I use both statistical, database-reliant approaches and traditional field-based sampling and logging. This research has included fieldwork in the Miocene of Central California, the Carboniferous of Northern England and Ireland, and will in the future be expanded to the Cambrian of California.

Collaborators: Prof. Dr. James Nebelsick (Tübingen), Prof. Steve Donovan (Naturalis Biodiversity Centre), Prof. Frank Corsetti (University of Southern California), Hank Woolley (University of Southern California).

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