Fossil types
Fossil Types and Where to Find Them
Most people start with a target in mind. They want an ammonite, or a shark tooth, or a trilobite. This page starts from that end and works backwards to the places where the group has actually been recorded.
Before you pick a target
Two things decide what a site can produce. The first is the age of the rock, because a group can only occur between its first and last appearance. The second is the environment the rock formed in. A shallow warm sea gives corals and brachiopods. A river floodplain gives plants and, occasionally, bone.
The counts below show how many documented sites on this website have recorded each group. They reflect our coverage rather than the true abundance of the fossils. Brachiopods lead partly because they are genuinely common in Paleozoic rock, and partly because we document a lot of Paleozoic sites.
One rule cuts across all of this. Vertebrate fossils are protected on public land in the United States, and in several countries all vertebrate material is state property. Check the access notes on a site page before you plan around a vertebrate find.
Shelled invertebrates
The most common finds on this website, and the usual starting point. Shells are made of calcium carbonate, which preserves well, so marine sedimentary rock of almost any age holds some of them.
57 sites
Ammonites
Ammonites are extinct shelled cephalopods that swam the seas from the Devonian until the end of the Cretaceous. Their coiled, often beautifully…
98 sites
Brachiopods
Brachiopods are bivalved marine animals that look superficially like clams but belong to a separate phylum. They were the dominant shelled benthic…
96 sites
Bivalves
Bivalves (clams, oysters, mussels) appear in marine sediments of every period from the Cambrian onward. They are particularly common in the Mesozoic…
56 sites
Gastropods
Gastropods (snails) are common throughout the marine fossil record. Mesozoic and Cenozoic gastropods often preserve exceptional shell detail. The…
Arthropods and graptolites
Both groups are extinct and both are excellent for dating rock. Trilobites ran from the Cambrian to the end of the Permian. Graptolites are colonial animals that look like pencil marks on shale, and they are the standard tool for dating Ordovician and Silurian sequences.
51 sites
Trilobites
Trilobites are extinct marine arthropods with three-part bodies, distantly related to modern horseshoe crabs. They lived from the Cambrian until the…
6 sites
Graptolites
Graptolites are extinct colonial hemichordates that drifted in Paleozoic oceans. They preserve as flattened carbonaceous compressions in dark shales,…
Echinoderms and corals
Sea floor animals that build skeletons from many separate plates or from a solid stony frame. Whole specimens are rare, because the plates come apart soon after death. Fragments are abundant, and in some limestones they make up most of the rock.
59 sites
Crinoids
Crinoids, 'sea lilies', are stalked echinoderms still living today, but at their Carboniferous peak they covered shallow sea floors in dense meadows.…
31 sites
Echinoids
Echinoids, sea urchins and their relatives, are common in Mesozoic-and-younger marine rocks. The chalk-and-flint of southern England and Denmark,…
58 sites
Corals
Coral fossils preserve the calcium carbonate skeletons of colonial reef-building animals. Devonian reefs of the British Wenlock and the Australian…
Vertebrates
The finds that draw the most attention and carry the most rules. Teeth survive better than bone, which is why shark teeth are the realistic vertebrate find on most trips. On public land in the United States, vertebrate fossils are protected and cannot be collected.
62 sites
Shark teeth
Shark teeth are among the most-collected fossils worldwide because sharks shed teeth continuously through life and the dense fluorapatite enamel…
64 sites
Fish
Fish fossils range from isolated teeth and scales (extremely common) to articulated skeletons (rare). The Devonian Gogo Formation (Western…
57 sites
Dinosaurs
Dinosaur fossils (bones, teeth, and trackways) are heavily protected almost everywhere. Most sites in this directory offer in-situ viewing of…
Plants
Leaf impressions, bark casts, and petrified wood. Coal measures and river deposits preserve them best, because plant material needs burial without oxygen. Petrified wood forms when silica replaces the cells, and it can keep the grain visible.
Other ways to browse
If you know the age of the rock near you, browse by geological period. If you know where you are going, browse by US state or by country. New collectors should start with the beginner guide.