Thursday, 13 August 2020


This adorable wee baby with his teeny aquatic mittens on is a eurypterid from exposures in New York, USA. This fellow is just under a centimetre in length but his cousins grew larger than a human. Eurypterids were the largest known arthropods to ever live. 

More commonly known as sea scorpions, eurypterids are an extinct group of arthropods that lived during the Paleozoic Era. We saw the first of their brethren during the Ordovician and the last of them during the End-Permian Mass Extinction Event. The group Arthropoda includes invertebrate animals with exoskeletons, segmented bodies, and paired joint appendages. Eurypterids had six sets of appendages. You can clearly see the segmented body on this cutie, which is one of the defining characteristics of arthropods. 

The first set was modified into pinchers which are used for feeding. The largest appendage visible in this fossil is a broad paddle that E. tetragonophthalmus used to swim. 

This first eurypterid, Eurypterus remipes, was discovered in New York in 1818. It is an iconic fossil for this region and was chosen at the state's official fossil in 1984. An excellent choice as most of the productive eurypterid-bearing outcrops are within the state's boundaries.