Research Interests

Birds, including penguins and the extinct Cretaceous seabird Hesperornis, have repeatedly adapted to marine life since the Mesozoic - often giving up the ability to fly in the process.  Art by Karen Carr

Birds, including penguins and the extinct Cretaceous seabird Hesperornis, have repeatedly adapted to marine life since the Mesozoic - often giving up the ability to fly in the process.  Art by Karen Carr

Ichthyosaurs and dolphins evolved remarkably similar body forms millions of years apart from each other, even though one is a reptile and the other is a mammal. Art by Karen Carr

Ichthyosaurs and dolphins evolved remarkably similar body forms millions of years apart from each other, even though one is a reptile and the other is a mammal. Art by Karen Carr

Skulls of the Miocene/Pliocene seal Acrophoca and the Cretaceous mosasaur Clidastes. The streamlined shapes and large, forward-pointing eye sockets suggest this marine mammal and ocean-dwelling lizard were each fast-swimming fish predators.  Specimens in the Smithsonian NMNH collections.

Skulls of the Miocene/Pliocene seal Acrophoca and the Cretaceous mosasaur Clidastes. The streamlined shapes and large, forward-pointing eye sockets suggest this marine mammal and ocean-dwelling lizard were each fast-swimming fish predators.  Specimens in the Smithsonian NMNH collections.

My primary research focus is the evolution and paleoecology of marine tetrapods, animals descended from land-dwelling ancestors that repeatedly readapted to marine life over the past 250 million years. Familiar living examples include whales, seals, penguins and sea turtles. The ecological roles of these modern animals were preceded by several extinct groups of marine reptiles during the Mesozoic such as ichthyosaurs and plesiosaurs.

These repeated invasions of the sea by land vertebrates provide a series of evolutionary experiments that help to reveal the mechanisms allowing different organisms to evolve dramatic shifts in anatomy and ecology.

These 'secondarily marine' animals have adapted to a variety of ecological roles–from herbivores to plankton eaters to apex predators. They therefore provide an important index of changes in global marine ecosystems over many millions of years.

Hind fin of the giant Triassic ichthyosaur Shonisaurus sikanniensis, at the Nevada State Museum, Las Vegas.

Hind fin of the giant Triassic ichthyosaur Shonisaurus sikanniensis, at the Nevada State Museum, Las Vegas.

I investigate bones and fossils in museum collections to compare the anatomy and ecology of living and extinct species. I also pursue fieldwork, primarily in Triassic aged rocks in western North America, to collect additional fossil material and better understand the geological and paleoenvironmental context of these fossils.