The new species, also distantly related to scorpions and horseshoe crabs, belongs to a group of arthropods with a large modified front leg called a “great appendage” which was used to snare prey.
Associate Professor Luke Parry, of the University of Oxford, said: “As well as having their beautiful and striking golden colour, these fossils are spectacularly preserved.
“They look as if they could just get up and scuttle away.”
The 450 million-year-old fossil was found at a site in New York State and has been named Lomankus edgecombei after arthropod expert Greg Edgecombe of London’s Natural History Museum.
