My research focuses on understanding the causes of organismal diversity patterns found over geologic time. Extrinsic factors such as climate change play an important role in regulating biodiversity, but the responses of different groups may be mediated by intrinsic factors, such as morphological innovations or constraints, that they inherit through their phylogenetic history. The fossil record provides the only long-term data we have on how organisms have responded to environmental changes, and how those reactions vary from group to group. As such, it is an important tool in understanding and predicting how organisms might respond in similar situations today.
Ungulates (hoofed mammals) are an ideal group to use in studies of diversity patterns for two fundamental reasons: many ungulate groups have living representatives, and ungulates have an exceptionally rich Cenozoic fossil record. We can use information from the living animals, such as molecular, physiological, and developmental data, to interpret extinct relatives. Fossil ungulates are morphologically diverse, occupy a wide variety of niches, and show a wide range of body sizes, all factors which play important roles in diversification.
My research into ungulate diversity patterns has taken two distinct approaches to these factors, one focusing on morphological evolution and patterns of diversification in a single lineage (Cetartiodactyla), and the other on extrinsic causes of changes in diversity in feeding guilds of ungulates during the Miocene.