List of the prehistoric life of Illinois

This list of the prehistoric life of Illinois contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Illinois.

The Paleobiology Database records no known occurrences of Precambrian fossils in Illinois.

The Paleobiology Database records no known occurrences of Mesozoic fossils in Illinois.

Life restoration of the Carboniferous amphibian Amphibamus
Illustration of a fossil of the Carboniferous-Permian spider Arthrolycosa . Charles Emerson Beecher (1889).
Life restoration of the Carboniferous amphibian Brachydectes
Life restoration of the Carboniferous Chimaera relative Caseodus
Life restoration (foreground) of the Permian-Jurassic lobe-finned fish Coelacanthus
Fossilized skeleton of the Carboniferous-Permian reptile relative Cricotus
Fossilized axial skeleton of the Carboniferous-Permian amphibian Diplocaulus
Illustration of fossil of the Carboniferous millipede Euphoberia
Life restoration of the Carboniferous four-limbed animal precursor Greererpeton
Fossil of the Middle-Late Ordovician giant trilobite Isotelus .
Life restoration of the Permian snake-like amphibian Lysorophus showing speculative egg-coiling behavior
Fossilized frond of the Carboniferous seed fern Neuropteris
Life restoration of the Carboniferous-Permian amphibian Phlegethontia .
Life restoration of the Carboniferous insects Protophasma and Titanophasma
Fossilized stump of the Carboniferous-Permian club moss relative Sigillaria
Restoration of the mysterious Carboniferous life-form Tullimonstrum , or the Tully monster
Mounted fossilized skeleton of the Pleistocene Bison antiquus , or ancient bison
Life restoration of the Pleistocene Cervalces scotti , or stag-moose
Restoration of a herd of Mammuthus primigenius , or wooly mammoths
Restoration of a herd of alarmed Miocene-Pleistocene peccaries of the genus Platygonus . Charles R. Knight (1922).
A living Rangifer tarandus , or reindeer