Eurypterids are an extinct group of aquatic arthropods often called 'sea scorpions' that lived from the Ordovician to the Permian periods. Collectors look for segmented exoskeletons preserved in fine-grained sedimentary rocks, often found in black shales or marine carbonates where anoxic conditions protected them from scavengers.
Is this eurypterid?
2-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Name the organismDecide what left the fossil before worrying about the rock. Organism: Sea scorpions (order Eurypterida). Age: Ordovician (about 480 million years ago) to the Permian; most species Silurian.
- 2Match the color rangeCompare against the expected color range: brown, black, tan, gray.
Often found alongside eurypterid
Minerals reported to co-occur with eurypterid. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Rarity
- Uncommon
- Uses
- Collector, Scientific study, Display
- Host rock
- sedimentary strata, typically shale, dolostone, or limestone
- Organism
- Sea scorpions (order Eurypterida)
- Age
- Ordovician (about 480 million years ago) to the Permian; most species Silurian
Where rockhounds find eurypterid
Classic worldwide localities
- New York, USA
- Ontario, Canada
- Saaremaa, Estonia
- Podillia, Ukraine
- Scotland
Field-hunting tip
Where it forms: sedimentary strata, typically shale, dolostone, or limestone. If you start seeing calcite, dolomite, pyrite in float, you are in the right ground.
Common questions
Where is eurypterid found?+
What minerals are found with eurypterid?+
What kind of rock does eurypterid form in?+
What is eurypterid used for?+
Find eurypterid on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
