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S. acuminata, which grew up to 40 centimeters long, belonged to a diverse group of predators known as eurypterids, whose oldest known species appeared about 467 million years ago.

Others are strangers to most of us: eurypterid, uintathere, onychophoran.

Analyses show that 59% of the chitin-protein complex from the ancient scorpion's exoskeleton, and 53% of that from the eurypterid's, was preserved in those thin veneers, the researchers reported online 3 February in .

It is the largest known walking trackway of a eurypterid or any invertebrate animal.

It is in the Old Red Sandstone that the eurypterids are best preserved; foremost among these was Pterygotus; P. anglicus has been found in Scotland with a length of nearly 6 ft.;