A compact alphabetical reference to Ohio’s major fossil groups, iconic species, and commonly encountered taxa.

A

Ammonoids (Devonian–Carboniferous) | Arthropods (trilobites, eurypterids, insects) | Archimedes Bryozoan (Mississippian, rare in Ohio)

B

Brachiopods (very abundant) | Bryozoans (lace corals) | Bivalves (clams, mussels)

C

Corals (horn corals, tabulate corals) | Crinoids (sea lilies) | Cephalopods (straight‑shelled nautiloids) | Conodonts (microfossils) | Coal‑age Plants (Carboniferous flora)

D

Dunkleosteus (Devonian armored fish) | Devonian Fish (placoderms, sharks) | Diatoms (Pleistocene microfossils)

E

Eurypterids (sea scorpions, Silurian) | Early Amphibians (Carboniferous) | Early Reptiles (Carboniferous)

F

Ferns (Carboniferous) | Fusulinids (microfossils, rare in Ohio) | Fish Scales & Teeth (Devonian)

G

Gastropods (snails) | Giant Beaver (Castoroides, Pleistocene) | Glacial Megafauna (mastodon, mammoth)

H

Horn Corals (Rugosa) | Horseshoe Crab Relatives (trilobite‑like forms) | Hyena‑like Ice Age Carnivores (very rare remains)

I

Isotelus Trilobite (Ohio’s state fossil) | Ice Age Plants (spruce, sedge, tundra flora)

J

Jawless Fish (Silurian–Devonian) | Jellyfish Impressions (rare)

L

Lepidodendron (scale trees) | Lycopsids (giant clubmosses) | Land Snails (Pleistocene)

M

Mastodon (state fossil mammal) | Mammoth | Marine Reptile Teeth (rare drift fossils) | Mollusks (bivalves, gastropods)

N

Nautiloids (straight‑shelled cephalopods) | Nodules (fossil‑bearing concretions)

O

Ostracods (microcrustaceans) | Orthocone Cephalopods | Ordovician Marine Fauna (Cincinnati region)

P

Placoderms (armored fish) | Plant Fossils (Carboniferous) | Petrified Wood (rare) | Pleistocene Vertebrates (megafauna)

R

Reef Corals (Silurian–Devonian) | Reptile Tracks (Carboniferous) | Rugose Corals

S

Sharks (Devonian teeth and spines) | Stromatolites (rare in Ohio) | Seed Ferns | Sea Lilies (crinoids)

T

Trilobites (multiple genera) | Tree Ferns | Tundra Mammals (Pleistocene)

V

Vertebrate Fossils (Devonian fish, Ice Age mammals) | Vascular Plants (Carboniferous)

W

Woolly Mammoth | Wood‑boring Insect Fossils (Carboniferous) | Warm‑water Reef Fauna (Silurian)

Z

Zygospira Brachiopods (Ordovician)