North american biodiversity: testing the effects of phylogeny and biogeography in late cretaceous and cenozoic mammals

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Understanding which factors affect species diversity in different environments is critical to our ability to predict the consequences of climatic changes. By looking at past periods of time we can begin to understand the long-term consequences of changes that we can otherwise only observe over very brief time scales. A number of factors can affect species diversity, including features that different groups inherit from their ancestors. In order to understand ancestral features, we need a well-resolved family tree. I am interested in the radiation of the group of terrestrial mammals that gave rise to whales. New data show that whales are descended from one group of ungulates, the artiodactyls (cows, pigs, camels and hippos), but we don't fully understand the details of the relationships of whales to their extinct ancestors. This research will clarify these relationships and allow study of diversity patterns over the 54 million year history of this group. Other external factors, such as how species are distributed across continents, and how they change over time, can also tell us a great deal about how those species may respond to major changes. This proposal will address how mammalian species diversity and distribution across North America changed over the time period from the age of dinosaurs, 70 million years ago, through the major climatic changes following the asteroid impact 65 million years ago, rapid global warming 56 million years ago, and slower cooling beginning about 34 million years ago. There is some evidence over this time period that some fossils found in western Canada are endemic and are not known from further south, and this proposal will test whether these differences are well supported and whether we should consider western Canada to belong to a separate bioregion that responded differently to change.