Silurian fossil of Eurypterus remipes from New York. This genus is less "spiney" than the genus depicted in the 2013 artwork. Photo by H. Zell (CC BY-SA 3.0).
Eurypterid Fossil Facts
- Eurypterids were fearsome aquatic predators of the Paleozoic. The 2011 National Fossil Day artwork featured a fearsome aquatic predator of the Mesozoic.
- Eurypterids were the largest arthropods, attaining sizes more than 8 feet long!
- They lived from about 460 to 270 million years ago (during the
Ordovician through Permian). Eurypterids are now extinct.
- The state fossil of New York is a Silurian eurypterid: Eurypterus remipes (the first eurypterid ever discovered).
Eurypterids were fearsome predators of Paleozoic seas across the globe. They were also among the largest arthropods (same phylum as insects, spiders, and crustaceans), getting up to more than eight feet in length. Early forms were marine, later eurypterids lived in brackish or even fresh water. There are about 250 species of eurypterids, all of them are now extinct. They range in age from the Ordovician to the Permian but are most diverse in rocks of the Silurian and Devonian (see a time scale). In North America they are found primarily in New York, Pennsylvania, Indiana, Illinois, and Ohio. The eurypterid in the logo is based on the Ordovician genus Megalograptus.
Eurpyterids, sometimes called "sea scorpions," have a fittingly predatory appearance. The front set of appendages are chelicerae that look like (but are not homologous to) scorpion pincers. Behind the chelicerae are legs. The last pair of appendages are paddles (modified legs) for swimming. At the end of the segmented body is a telson that can be a spike, a paddle, or set of pincers. Although the telson looks similar to a scorpion's stinger, it is unlikely that eurypertids could sting. Nevertheless, you probably wouldn't want to tangle with one that was longer than you are tall! Eurypterids probably ate, or scavenged, just about anything they could catch or fit in their mouth. The trilobites shown in the logo may have been a common meal.
The name eurypterid is derived from the Greek word for "wide" or "broad" (eurys) and the Greek word for "wing" (pteryx). "Wide or broad wing" refers to the wide swimming paddles.