Project Report

My major research focus is on understanding how we can use the fossil record to understand the ecological change going on all around us. So far, I have adopted two main approaches: 1) trying to understand how the biases in the process of fossilization might mislead us about past ecosystems, 2) trying to put modern changes into a broader context. Much of my work has focused on birds. Birds have very lightly built skeletons and tend to be very small, so they fossilize very, very poorly. However, we have an immense amount of information on their ecology and evolution based on the modern world. My project is focused on using birds as a "worst case scenario". Any ecological processes we can see in the bird fossil record, should also be observable in the records of better preserved groups. My project in the summer of 2011 was to go to China and to examine the ecology of the earliest "avifauna", or collection of birds from a single place and time. The fossils I was looking at all came from a 125 million year old forest, right by a large, volcanic lake. The birds that died over the lake and sank to the bottom. Because of chemicals released from the volcanic gases, as well as the depth of the lake, there was a unique layer at the very bottom that stopped the decay process. The end result is that we have stunning fossil birds from this particular forest, preserved with feathers, beaks and toenails still intact. My analysis has shown, quite conclusively, that this ancient bird assemblage was utterly unlike most modern assemblages. You would have a really hard time finding any forest with the same selection of birds. Most of the birds were either ground-foraging, like quails or pheasants, or brush foraging, like flickers or cardinals. Very few birds lived in the treetops or in the water, although one fossil bird does seem very much like a grebe. Further, the extreme differences between this fossil bird community and modern bird communities cannot be explained by "taphonomy", or the process of fossilization. Loons and swans are more likely to be found as fossils than swifts or hummingbirds because loons and swans are bigger, have more robust bones, and live in lakes, where most bird-bearing fossil deposits are formed. So any fossil bird deposit is likely to have a bias, and under-represent small, forest-dwelling birds. However, even when this bias is taken into account using simulations and mathematical modeling, the ancient bird community of China stands out. The uniqueness of this oldest bird community can tell us a lot, not only about bird evolution and origins, but also about how we understand the ecology of ancient deposits. With a better approach to inferring ecosystem dynamics in the fossil record, we can start to build a baseline of ecosystem change, that will better let us assess how human-induced changes to modern ecosystems compare to those observed in the dark mists of deep time.

Agency
National Science Foundation (NSF)
Institute
Office of International and Integrative Activities (IIA)
Application #
1107676
Program Officer
Carter Kimsey
Project Start
Project End
Budget Start
2011-06-01
Budget End
2012-05-31
Support Year
Fiscal Year
2011
Total Cost
$5,700
Indirect Cost
Name
Mitchell Jonathan S
Department
Type
DUNS #
City
Chicago
State
IL
Country
United States
Zip Code
60637