Climate Change and Preservation Bias in the Pliocene Ringold Formation

Presenter: Christina Wilson, Geology

Before oscillations of glacial and interglacial cycles began, the climate within the Pliocene epoch, (5.3 – 2.6 Ma) was relatively temperate –similar to more conservative projections for the next 100 years of our current climate. Therefore, this time period provides an excellent basis for predicting how present fauna may respond to climate change. This study compares sites with different geologic ages but similar locations to examine faunal changes over time. This will show how different factors, including climate, impact the ecosystem. I researched the Ringold Formation, located in South-Central Washington, which is early Blancan in age (4.75-1.80 Ma) and within the Pliocene epoch. I picked fossils from screened sediment, identified different types of fossil, and classified those most amenable to identification. One of the main components of the collection is Mimomys teeth. Classification of 419 teeth shows that the morals are not in the same proportions as in living Mimomys, suggesting preservation bias and highlighting the importance of sampling all members of an ecosystem. Rabbit and squirrel teeth were also classified. These were fewer in number, so conclusions could not be drawn as clearly. Further identification and cataloguing of species will enable a fuller picture of the environment preserved and continue to shed light on the changing fauna through time.