To date, I have primarily worked with the mammalian order Carnivora, looking at trends in the evolution of their body and brain size. I continue to pursue research in the Carnivora. However, I also maintain active interests in many other mammalian taxa, including rodents, artiodactyls, and primates. In addition, I am interested in the origin of jawed vertebrates, specifically with respect to the early diversification of body plans in living and extinct groups. I currently work with several Palaeozoic groups, including chondrichthyans (sharks and their relatives), placoderms and acanthodians (two extinct grades of jawed fish).

My subject interests in evolutionary biology are varied and cover a wide range: from total evidence phylogenetics, comparative anatomy and description, to biometry, morphometrics, and macroecology/macroevolutionary processes. These interests are united under a broad theme of developing quantitative techniques to try to understand evolutionary processes.

I am currently working on several projects in the Carnivora, including a large-scale total evidence phylogeny and a project looking to reconstruct rates of evolution through time and across phylogeny.

In addition, I have several ongoing efforts in early gnathostome evolution, with the goal of better understanding the ancestral conditions for the last common ancestors to all living jawed vertebrates. The scope of this research spans morphological description, to phylogenetic analysis, to application of comparative methods, to morphometrics. An important project in this area uses the fossil record as a natural experiment to test hypotheses concerning the evolutionary and developmental pathways responsible for the make-up of the vertebrate visceral skeleton.

Finally, I have several follow-up projects concerning my previous work on diversity dynamics in the rodent fossil record of the western USA, linking patterns of origination and extinction to region-level records of tectonism and climate change.