PLEISTOCENE FOSSIL BIRDS FROM IOWA LOCALITIES

Rocks of appropriate ages and environments of deposition that could potentially contain fossil birds are present in Iowa. These include Jurassic evaporites near Fort Dodge, although decades of mining have not revealed fossils. Cretaceous fluvial rocks are present in the western portion of the state, but these rocks are poorly exposed at the surface. Pleistocene glacial deposits cover much of the state, and the Loess Hills contain Pleistocene windblown deposits and volcanic ash layers that contain significant vertebrate faunas in Nebraska and elsewhere. In addition, karst features of the Paleozoic carbonate rocks of Iowa include innumerable caves and sinkholes.

Despite the exposures of these rocks and presence of potential traps, published reports of fossil birds from Iowa are scarce. Avian fossils have been collected in Iowa, primarily in connection with screen-washing of Pleistocene deposits by University of Iowa researchers, but most of these have not been studied. In the current study, avian remains have been identified from the Dutch Creek and Garrett Farm localities (University of Iowa Paleontology Collections). Preliminary examination of these fossils shows they represent passerine birds, including the Bobolink (Dolichonyx oryzivorus) and Common Yellowthroat (Geothlypis trichas).