The Devonian in Iowa, US

Paleontology and geology

Warm, shallow seas covered Iowa during Devonian time. These waters were home to numerous marine invertebrates including abundant brachiopods, trilobites, rugose and tabulate corals, and echinoderms, and, for the first time, a variety of fish. Reefs flourished in the state; stromatoporoids (extinct organisms related to sponges) formed variously shaped colonies that resembled layered mats, branches, and rounded masses. Large colonial and solitary corals joined these sponges to form extensive reefs, some of which can be traced for over 100 miles in eastern Iowa. Many of these fossils can be seen at Devonian Fossil Gorge, several miles upstream from Iowa City along the Iowa River.