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.

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

Selected Paleozoic taxa of Illinois

 * †Achatella
 * †Actinoceras
 * †Alethopteris
 * †Alethopteris decurrens
 * †Alethopteris lonchitica
 * †Alethopteris owenii
 * †Alethopteris serlii
 * Amphibamus BW.jpg †[[Amphibamus]] – type locality for genus
 * †Amphibamus grandiceps – type locality for species
 * †Amphiscapha
 * †Amynilyspes – type locality for genus
 * †Annularia
 * †Annularia asteris – or unidentified comparable form
 * †Annularia stellata
 * †Anomphalus – type locality for genus
 * †Anthracoceras
 * †Archaeocidaris – tentative report
 * †Archaeopteris
 * †Archimedes
 * †Archimedes communis
 * †Archimedes compactus
 * †Archimedes invaginatus
 * †Archimedes lativolvis
 * †Archimedes macfarlani
 * †Archimedes swallovanus
 * †Archimedes terebriformis
 * †Archimylacris
 * †Arctinurus
 * Arthrolycosa antiqua, Beecher illustration.jpg †[[Arthrolycosa]] – type locality for genus
 * †Artisia
 * †Asterotheca
 * †Asterotheca miltoni – or unidentified comparable form
 * †Asyncritus – type locality for genus
 * †Athyris
 * †Atrypa
 * †Atrypa reticularis – report made of unidentified related form or using admittedly obsolete nomenclature
 * †Aviculopecten
 * †Aviculopecten fasciculatus
 * † Avonia
 * †Bandringa – type locality for genus
 * †Bassleroceras
 * †Bellerophon
 * †Bellerophon spergensis
 * †Belinurus
 * †Bembexia
 * †Blattoidea
 * Brachydectes.jpg †[[Brachydectes]]
 * †Brachydectes newberryi
 * †Bumastus
 * †Bumastus armatus – or unidentified comparable form
 * †Bumastus chicagoensis
 * †Bumastus cuniculus – or unidentified comparable form
 * †Bumastus graftonensis
 * †Bumastus insignis
 * †Bumastus springfieldensis
 * †Bumastus transversalis
 * †Calamites
 * †Calamites suckowii
 * †Callipteridium
 * †Calvinia
 * †Calymene
 * †Calymene breviceps
 * †Calymene celebra
 * †Calyptaulax
 * †Camarotoechia
 * Caseodus cropped.png †[[Caseodus]]
 * †Cephalerpeton – type locality for genus
 * †Cephalerpeton ventriarmatum – type locality for species
 * †Ceratiocaris
 * †Ceratocephala
 * †Ceraurinella
 * †Ceraurinus
 * †Ceraurus
 * †Cheirurus
 * †Chonetes
 * †Chonetes ornatus
 * †Cleiothyridina
 * †Cleiothyridina atrypoides
 * †Cleiothyridina sublamellosa
 * †Clepsydrops – type locality for genus
 * †Cliftonia
 * Coelacanthus cropped.png †[[Coelacanthus]]
 * †Composita
 * †Composita subtilita
 * †Composita trinuclea
 * †Conocardium
 * †Cooperoceras
 * †Cordaicarpus
 * †Cordaites
 * †Cordaites principalis
 * †Cornulites
 * †Crania
 * †Craniops
 * Cricotus crassidens.JPG †[[Cricotus]] – type locality for genus
 * †Crotalocrinites
 * †Ctenacanthus
 * †Ctenacanthus buttersi – type locality for species
 * †Curriella – tentative report
 * †Cyathocrinites
 * †Cyclonema
 * †Cyclus
 * †Cyphaspis
 * †Cyrtoceras
 * †Dalmanites
 * †Deiphon
 * †Dicoelosia
 * †Dictyonema
 * †Dimerocrinites
 * †Dimerocrinites occidentalis
 * Exhibit Museum of Natural History, Ann Arbor - IMG 9136.JPG †[[Diplocaulus]] – type locality for genus
 * †Domatoceras
 * †Echinaria
 * †Edestus
 * †Edmondia
 * †Elonichthys
 * †Encrinurus
 * †Eodictyonella
 * †Eophacops
 * †Eophacops handwerki
 * †Eospirifer
 * †Eospirifer radiatus
 * †Erratencrinurus
 * †Eucalyptocrinites
 * †Eucalyptocrinites crassus
 * †Euomphalus
 * †Euomphalus planodorsatus
 * Euphoberia spinulosa.jpg †[[Euphoberia]] – type locality for genus
 * †Euphoberia armigera – type locality for species
 * †Favosites
 * †Fenestella
 * †Fletcheria
 * †Gerarus – type locality for genus
 * †Glikmanius
 * †Glikmanius occidentalis
 * †Glyptambon
 * †Glyptopleura
 * †Gondolella
 * †Graeophonus
 * †Graeophonus scudderi – type locality for species
 * †Greenops
 * Greererpeton DB2.jpg †[[Greererpeton]]
 * †Hallopora – tentative report
 * †Halysites
 * †Harpidium
 * †Helenodora – type locality for genus
 * †Helenodora inopinata – type locality for species
 * †Heliomeroides
 * †Holia
 * †Hyolithes
 * †Ilyodes
 * †Isodectes
 * Isotelus brachycephalus.JPG †[[Isotelus]]
 * †Isotelus gigas
 * †Isotelus maximus
 * †Kionoceras
 * †Latzelia – type locality for genus
 * †Latzelia primordialis – type locality for species
 * †Lepidodendron
 * †Lepidodendron aculeatum
 * †Lepidophyllum
 * †Lepidostrobus
 * †Lichas
 * †Lingula
 * †Liroceras
 * Lithophaga – tentative report
 * Lysorophus.jpg †[[Lysorophus]] – type locality for genus
 * †Marsupiocrinus
 * †Meristina
 * †Metacoceras
 * †Milosaurus – type locality for genus
 * †Monograptus
 * †Monograptus dubius
 * †Murchisonia
 * †Naticopsis
 * †Naticopsis carleyana
 * †Naticopsis planifrons
 * †Naticopsis waterlooensis – type locality for species
 * †Nemastomoides – type locality for genus
 * †Neospirifer
 * †Neospirifer dunbari
 * †Neospirifer triplicatus
 * Neuropteris cropped.jpg †[[Neuropteris]]
 * †Neuropteris ovata
 * †Neuropteris rarinervis
 * †Neuropteris scheuchzeri
 * †Neuropteris tenuifolia
 * †Nodonema
 * Nucula
 * †Nuculoidea – tentative report
 * †Onychopterella – tentative report
 * †Palenarthrus – type locality for genus
 * †Palenarthrus impressus – type locality for species
 * †Paraisobuthus
 * †Pecopteris
 * †Pecopteris plumosa
 * †Pentremites
 * †Pentremites tulipaformis
 * †Periechocrinus
 * †Phacops
 * Phlegethontia.jpg †[[Phlegethontia]]
 * †Phlegethontia longissima – type locality for species
 * †Phragmolites
 * †Platyceras
 * †Platysomus
 * †Platystrophia
 * †Plicochonetes
 * †Polysentor – type locality for genus
 * †Priapulites – type locality for genus
 * †Priapulites konecniorum – type locality for species
 * †Prodentalium
 * †Proetus
 * Titanophasma and Protophasma.jpg †[[Protophasma]]
 * †Protopilio
 * †Pseudophlegethontia – type locality for genus
 * †Pseudophlegethontia turnbullorum – type locality for species
 * †Pterochiton
 * †Pterotheca
 * †Rasstriga – type locality for genus
 * †Rasstriga americana – type locality for species
 * †Remopleurides
 * †Rhodea
 * †Rhynchonella
 * †Saccoglossus
 * †Sagenodus
 * †Samaropsis
 * †Savagella
 * †Scepasma – type locality for genus
 * Stanhope Tree - geograph.org.uk - 2531669.jpg †[[Sigillaria]]
 * †Silphion – type locality for genus
 * † Simplicius
 * †Skenidioides
 * Solemya
 * †Solenochilus
 * †Sphaerexochus
 * †Sphaerocoryphe
 * †Sphenophyllum
 * †Sphenophyllum cuneifolium
 * †Sphenophyllum emarginatum
 * †Sphenophyllum longifolium – or unidentified comparable form
 * †Sphenopteris
 * †Stearoceras
 * †Stethacanthus
 * †Stethacanthus altonensis
 * †Stigmaria
 * †Strophomena
 * †Symmorium – type locality for genus
 * †Syringopora
 * †Tainoceras
 * †Tentaculites
 * †Tranodis
 * Tullimonstrum NT small cropped.jpg †[[Tullimonstrum]] – type locality for genus
 * †Wilkingia
 * †Worthenia
 * †Xyloiulus
 * Yoldia

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

Cenozoic

 * Agabus
 * †Agabus praelugens – type locality for species
 * †Agabus savagei – type locality for species
 * †Anomodon – type locality for genus
 * †Anomodon snyderi – type locality for species
 * †Araloselachus
 * †Araloselachus cuspidata
 * Arvicola
 * †Bananogmius
 * †Bananogmius crieleyi – or unidentified comparable form
 * Bison
 * Bison antiquus.jpg †[[Bison antiquus]]
 * †Bison bison
 * Blarina
 * †Bootherium
 * †Bootherium bombifrons
 * Carabus
 * †Carabus maeander
 * Castor
 * †Castor canadensis
 * †Castoroides
 * †Castoroides ohioensis
 * †Cervalces
 * †Cervalces latifrons – tentative report
 * Life restoration cervalces scotti.jpg †[[Cervalces scotti]]
 * Chelonia
 * Chlaenius
 * †Chlaenius plicatipennis – type locality for species
 * Conopeum
 * †Conopeum damicornis
 * Donacia
 * †Donacia stirioides – type locality for species
 * Equus
 * Esox
 * †Euceratherium
 * †Euceratherium collinum
 * Geomys
 * †Geomys bursarius
 * †Ischyodus
 * †Ischyodus williamsae
 * Lasiopodomys
 * †Lasiopodomys deceitensis
 * †Mammut
 * †Mammut americanum
 * †Mammuthus
 * Ice age fauna of northern Spain - Mauricio Antón cropped.png †[[Mammuthus primigenius]]
 * Marmota
 * †Marmota monax
 * †Megalonyx
 * †Megalonyx jeffersonii
 * Mesalia
 * †Mesalia alabamiensis
 * Microtus
 * †Microtus paroperarius
 * Natica
 * †Natica reversa
 * Olophrum
 * †Olophrum henryi – type locality for species
 * Ostrea
 * †Ostrea pulaskensis
 * †Pachyrhizodus
 * †Pachyrhizodus caninus
 * Patrobus
 * †Patrobus henshawi – type locality for species
 * Peromyscus
 * Pitar – tentative report
 * †Pitar ripleyanus
 * Pituophis
 * Platygonus leptorhinus cropped.png of the genus Platygonus. Charles R. Knight (1922).]] †Platygonus – type locality for genus
 * †Platygonus compressus – type locality for species
 * †Platygonus cumberlandensis – tentative report
 * Platynus
 * †Platynus calvini – type locality for species
 * †Platynus pleistocenicus – type locality for species
 * †Platynus subgelidus – type locality for species
 * Procyon
 * †Procyon lotor – type locality for species
 * †Propenser
 * †Propenser hewletti
 * †Ptychodus
 * Rangifer
 * Reinbukken på frisk grønt beite. - panoramio cropped.jpg †[[Rangifer tarandus]]
 * †Sangamona
 * †Sangamona fugitiva
 * Sorex
 * †Strepsidura
 * †Strepsidura contorea
 * Sylvilagus
 * †Sylvilagus floridanus
 * Ursus
 * †Ursus americanus
 * Venericardia
 * †Venericardia smithii