Paleozoic
Selected Paleozoic taxa of Illinois
- † Achatella
- † Actinoceras
- † Alethopteris
Life restoration of the Carboniferous amphibian Amphibamus - † 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
- † Archimylacris
- † Arctinurus
Illustration of a fossil of the Carboniferous-Permian spider Arthrolycosa . Charles Emerson Beecher (1889). - † 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
- † Avonia
- † Bandringa – type locality for genus
- † Bassleroceras
- † Bellerophon
- † Belinurus
- † Bembexia
- † Blattoidea
Life restoration of the Carboniferous amphibian Brachydectes - † Bumastus
- † Bumastus armatus – or unidentified comparable form
- † Bumastus chicagoensis
- † Bumastus cuniculus – or unidentified comparable form
- † Bumastus graftonensis
- † Bumastus insignis
- † Bumastus springfieldensis
- † Bumastus transversalis
- † Calamites
- † Callipteridium
- † Calvinia
- † Calymene
- † Calyptaulax
- † Camarotoechia
Life restoration of the Carboniferous Chimaera relative Caseodus - † Cephalerpeton – type locality for genus
- † Cephalerpeton ventriarmatum – type locality for species
- † Ceratiocaris
- † Ceratocephala
- † Ceraurinella
- † Ceraurinus
- † Ceraurus
- † Cheirurus
- † Chonetes
- † Cleiothyridina
- † Clepsydrops – type locality for genus
- † Cliftonia
Life restoration (foreground) of the Permian-Jurassic lobe-finned fish Coelacanthus - † Composita
- † Conocardium
- † Cooperoceras
- † Cordaicarpus
- † Cordaites
- † Cornulites
- † Crania
- † Craniops
Fossilized skeleton of the Carboniferous-Permian reptile relative Cricotus - † Crotalocrinites
- † Ctenacanthus
- † Ctenacanthus buttersi – type locality for species
- † Curriella – tentative report
- † Cyathocrinites
- † Cyclonema
- † Cyclus
- † Cyphaspis
- † Cyrtoceras
- † Dalmanites
- † Deiphon
- † Dicoelosia
- † Dictyonema
- † Dimerocrinites
Fossilized axial skeleton of the Carboniferous-Permian amphibian Diplocaulus - † Domatoceras
- † Echinaria
- † Edestus
- † Edmondia
- † Elonichthys
- † Encrinurus
- † Eodictyonella
- † Eophacops
- † Eospirifer
- † Erratencrinurus
- † Eucalyptocrinites
- † Euomphalus
Illustration of fossil of the Carboniferous millipede Euphoberia - † Euphoberia armigera – type locality for species
- † Favosites
- † Fenestella
- † Fletcheria
- † Gerarus – type locality for genus
- † Glikmanius
- † Glyptambon
- † Glyptopleura
- † Gondolella
- † Graeophonus
- † Graeophonus scudderi – type locality for species
- † Greenops
Life restoration of the Carboniferous four-limbed animal precursor Greererpeton - † Hallopora – tentative report
- † Halysites
- † Harpidium
- † Helenodora – type locality for genus
- † Helenodora inopinata – type locality for species
- † Heliomeroides
- † Holia
- † Hyolithes
- † Ilyodes
- † Isodectes
Fossil of the Middle-Late Ordovician giant trilobite Isotelus . - † Kionoceras
- † Latzelia – type locality for genus
- † Latzelia primordialis – type locality for species
- † Lepidodendron
- † Lepidophyllum
- † Lepidostrobus
- † Lichas
- † Lingula
- † Liroceras
- Lithophaga – tentative report
Life restoration of the Permian snake-like amphibian Lysorophus showing speculative egg-coiling behavior - † Marsupiocrinus
- † Meristina
- † Metacoceras
- † Milosaurus – type locality for genus
- † Monograptus
- † Murchisonia
- † Naticopsis
- † Naticopsis carleyana
- † Naticopsis planifrons
- † Naticopsis waterlooensis – type locality for species
- † Nemastomoides – type locality for genus
- † Neospirifer
Fossilized frond of the Carboniferous seed fern Neuropteris - † Nodonema
- Nucula
- † Nuculoidea – tentative report
- † Onychopterella – tentative report
- † Palenarthrus – type locality for genus
- † Palenarthrus impressus – type locality for species
- † Paraisobuthus
- † Pecopteris
- † Pentremites
- † Periechocrinus
- † Phacops
Life restoration of the Carboniferous-Permian amphibian 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
Life restoration of the Carboniferous insects Protophasma and Titanophasma - † 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
Fossilized stump of the Carboniferous-Permian club moss relative 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
- † Stigmaria
- † Strophomena
- † Symmorium – type locality for genus
- † Syringopora
- † Tainoceras
- † Tentaculites
- † Tranodis
Restoration of the mysterious Carboniferous life-form Tullimonstrum , or the Tully monster - † Wilkingia
- † Worthenia
- † Xyloiulus
- Yoldia
