Ancient Spider Ancestor Fossilized in 3D by Fool’s Gold

A 450-million-year-old fossil of an ancient relative of spiders has been unearthed, preserved in three dimensions by fool’s gold. This newly identified species, which shares a distant lineage with arachnids such as scorpions and horseshoe crabs, was discovered by a research team led by the University of Oxford. It is categorized within a group of arthropods known as megacheirans, which possess a large, modified leg at the front of their bodies, used for capturing prey. Associate Professor Luke Parry, from the university’s department of earth sciences, stated that the fossils were “spectacularly preserved”. The fossil was located at a site within the renowned Beecher’s Trilobite Bed in New York State, a rock layer containing numerous well-preserved fossils. The creatures preserved there inhabited a hostile environment with low oxygen levels. This condition allowed iron pyrite, commonly known as fool’s gold, to replace parts of their bodies after they were buried, resulting in golden, three-dimensional fossils. The new species has been named *lomankus edgecombei*, in honor of arthropod expert Greg Edgecombe of London’s Natural History Museum. Experts suggest that this discovery illuminates the long-standing puzzle of how arthropods evolved the various parts on their heads. These can include the antennae of insects and crustaceans, as well as the pincers and fangs of spiders and scorpions. However, unlike other megacheirans, the flexible, whip-like hairs of this creature indicate it used its frontal appendage to sense its surroundings, rather than for capturing prey. Associate Professor Parry, who headed the research team, commented that the fossils “look as if they could just get up and scuttle away”. “Part of the key to this success is their highly adaptable head and its appendages, that has adapted to various challenges like a biological Swiss army knife”, he said. He added, “As well as having their beautiful and striking golden colour, these fossils are spectacularly preserved.”