Counts of sites by county for Cenozoic fossil marine invertebrates used to create Figure 1, specifically the number of sites (collections) from the Paleobiology Database download, and the number of sites (localities) digitally mobilized from nine institutions of the EPICC TCN. The Paleobiology Database download was performed on November 10 2017 using the following query:,Cenozoic&cc=US&envtype=marine&show=loc,paleoloc,strat,stratext,lith,geo,methods,resgroup,refattr,secref,ent,entname. The nine institutions are: Burke Museum of Natural History and Culture, University of Washington, Seattle, WA; California Academy of Sciences, San Francisco, CA; Natural History Museum of Los Angeles County, Los Angeles, CA; National Museum of Natural History, Smithsonian Institution, Washington, DC; Orange County Paleontological Collection, Fullerton, CA; Paleontological Research Institution, Ithaca, NY; University of Alaska Museum, University of Alaska, Anchorage, AK; University of California Museum of Paleontology, Berkeley, CA; University of Oregon Museum of Natural History, Eugene, OR. Data from both Paleobiology Database collections and museum collections were cleaned to remove terrestrial strata erroneously categorized as marine.