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.

When did eurypterids go extinct?

The eurypterids appeared at the beginning of the Ordovician Period (about 488 million years ago) and became extinct at the end of the Permian Period (about 251 million years ago).

Are there any living eurypterids?

This giant was the last known surviving eurypterid. No eurypterids are known from fossil beds higher than the Permian. This indicates that the last eurypterids died either in the catastrophic extinction event at its end or at some point shortly before it.