Mazon Creek Fossil Invertebrates
The Mazon Creek fauna is one of the world's most important soft-bodied fossil faunas. There are over 300 fossil animal species from 13 phyla preserved in this fauna. Many of the fossils in the Mazon Creek fauna are unique and found nowhere else in the world. The Mazon Creek area includes the following counties of northeastern Illinois: Will, Grundy, Kankakee, LaSalle, and Livingston. The fossils are preserved in ironstone concretions or nodules which preserved many soft-bodied animals and plants that are rarely fossilized. During the Pennsylvanian this area of Illinois was covered with coastal swamps, deltas, and upland forests situated along an estuary bay. The fossils include animals and plants that lived in the surrounding swamps and forests; as well as animals that lived in fresh and brackish water of the rivers, ponds, and estuary; and some marine animals that lived in the shallow sea covering western Illinois. The Field Museum's collection is the most comprehensive collection of these fossils. The photos below are just a small glimpse into the 40,000 plus specimens of the FMNH fossil invertebrates collection.