''Attercopus'' is an extinct genus of

arachnid Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegar ...

s, containing one species ''Attercopus fimbriunguis'', known from flattened cuticle fossils from the Panther Mountain Formation in

Upstate New York Upstate New York is a geographic region consisting of the area of New York State that lies north and northwest of the New York City metropolitan area. Although the precise boundary is debated, Upstate New York excludes New York City and Long Is ...

. It is placed in the extinct order

Uraraneida Uraraneida is an extinct order of arachnids, known from fossils of Middle Devonian, Permian and possibly Cretaceous age. Two genera of fossils have been definitively placed in this order: ''Attercopus'' from the Devonian of United States and '' ...

, spider-like animals able to produce

silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the ...

, but which lacked true spinnerets and retained a segmented abdomen bearing a flagellum-like tail resembling that of a

whip scorpion Thelyphonida is an arachnid order comprising invertebrates commonly known as whip scorpions or vinegaroons (also spelled vinegarroons and vinegarones). They are often called uropygids in the scientific community based on an alternative name for ...

. They are thought to be close to the origins of spiders. Its name is taken from the English dialect word ''attercop'' ("spider"), which came from '' ang, attorcoppa'' ("poison-head"), from '' ang, ator'' ("poison"), itself drawn from the

Proto-Germanic Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the reconstructed proto-language of the Germanic branch of the Indo-European languages. Proto-Germanic eventually developed from pre-Proto-Germanic into three Germanic bran ...

''*aitra-'' ("poisonous ulcer") and ''kopp-'' ("head"). An important Early Devonian (about ) fossil example from Gilboa, New York, was originally described as a member of the extinct order

Trigonotarbida The order Trigonotarbida is a group of extinct arachnids whose fossil record extends from the late Silurian to the early Permian ( Pridoli to Sakmarian).Dunlop, J. A., Penney, D. & Jekel, D. 2020A summary list of fossil spiders and their relative ...

and named ''Gelasinotarbus? fimbriunguis''. It was later assigned to a new genus ''Attercopus'' and reinterpreted as the oldest, and most primitive, example of a true spider (

Araneae Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species dive ...

). This hypothesis was based on the supposed presence of unique spider features such as silk-producing

spinnerets A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and are ...

and the opening of a venom gland on the fang of the

chelicera The chelicerae () are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated fangs, or similarly ...

. Further study – based on new fossils from a comparable Devonian locality called South Mountain – and comparison with other material from the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

, i.e., of '' Permarachne'', indicates that ''Attercopus'' does not actually have spinnerets. The feature which looked like a tubular spinneret is actually a folded sheet of cuticle. It would, however, have produced silk from a series of silk gland openings, or spigots, located across plates on the underside of the abdomen. The opening for the venom gland is also a misinterpretation. A segmented tail, or flagellum, also belonged to this animal. It seems unlikely that ''Attercopus'' spun webs, but it may have used its silk to wrap eggs, lay draglines or construct burrow walls. ''Attercopus fimbriunguis'' is not a spider, but it is probably close to the type of animals which did give rise to modern spiders today.

References

{{Taxonbar, from=Q2870066 Devonian arachnids Devonian arthropods of North America Monotypic arachnid genera Fossil taxa described in 1987