Paleontological investigations have played a critical role in the research of the U.S. Geological Survey (USGS) since its founding in 1879. From about 1950 until recently, the bulk of these fossil materials collected by USGS field geologists was housed in the U.S. National Museum of Natural History (Smithsonian Institution) in Washington, D.C, under the control of the Branch of Paleontology and Stratigraphy of the USGS. Large biostratigraphic sets of USGS collections also resided in Denver, Colorado, and Menlo Park, California, at the USGS regional centers.