Tag: Dana Reuter

Fossils of Oregon: Mammalian Body Mass Communities in the Miocene

Presenter(s): Dylan Carlini − Geology

Faculty Mentor(s): Samantha Hopkins, Dana Reuter

Poster 9

Research Area: Earth and Biological science

Funding: Presidential Undergraduate Research Scholarship
UROP Mini-Grant

The size of an organism relates to a host of other characteristics about a species such as diet, metabolism, and trophic level. Changes in body mass through deep time are often the result of changing environments and climates. Previous research has examined how the patterns of mammalian body size at a community scale are shaped by the environments the organisms inhabit. However, the fossil record of Eastern Oregon has never been investigated through that lens. The extensive fossil record and well-studied long-term environmental shifts in Eastern Oregon make it an ideal location to study the effects of environmental changes on mammalian body masses. This study intends to classify and quantify the effects of the spread of grasslands on body size structure of mammals in the Miocene. I estimated body mass for Miocene mammals using measurements from fossil teeth as a proxy. These estimates derive from measurements taken with digital calipers and from the computer program Image J. I then organized the body masses into size categories and compared the changes in size structures as Oregon developed from a closed woodland in the middle Miocene to a more open, grassland environment in the late Miocene. If a pattern is discovered, it could help inform biologists and ecologists which varieties of mammal are at the greatest risk of climate-change related extinction in the near future.

The Evolution of Camelids in the Pacific Northwest in Response to the Grassland Expansion

Presenter(s): Eleanor Froehlich—Earth Sciences

Faculty Mentor(s): Samantha Hopkins, Dana Reuter

Session 6: The Earth, Sky & Everything In Between

Camelids, the artiodactyl group including camels, llamas, and alpacas, evolved in North America during the Eocene . The first camelids were smaller than a goat; however, some extinct genera were giraffe sized . Most studies of North American camelids focus on fossils found in the Great Plains and as a result little is known about how camelid diversity responded to climate and vegetation changes in the Pacific Northwest. Horses are a well-studied example of ungulate responses to climactic changes and grassland expansion . They show a general increase in body size that is concurrent with their switch from browsing to mixed feeding and eventually to the grazing we see in modern examples . I suspect that as the environment in the Pacific Northwest dried out, camelids also increased in size due to the grassland expansion . I also believe that camelids incorporated more grasses into their diet . I tested this by documenting camelid diversity in the Pacific Northwest, specifically the states of Idaho, Oregon, and Washington, using the published fossil occurrences on the Paleobiology Database . Body size data was estimated using tooth measurements collected on the Fossilworks database . Camelid species were categorized according to two ecological parameters, body size and diet . I used these to track camelid evolution through time . I found that although body mass does increase there were still small browsing lineages late into the Miocene . This study provides a broader biogeographical picture of how grassland expansion influenced camelid evolution and ecology .