Uraraneida
| Uraraneida Temporal range: Middle Devonian–Permian |
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| artist's reconstruction of Attercopus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Arachnida |
| Clade: | Tetrapulmonata |
| Order: |
†Uraraneida Selden & Shear, 2008 |
Uraraneida is an extinct order of arachnids, known from fossils of Middle Devonian and Permian age, suggesting the order persisted from at least 393 to 252 million years ago. As of March 2016[update], two genera of fossils were placed in this order: Attercopus and Permarachne. They were initially identified as spiders, but now constitute the Uraraneida, a separate but closely related group.
The first fossil now placed in the order was found in Gilboa, New York. In 1987, it was initially tentatively placed in the extinct order Trigonotarbida and named Gelasinotarbus? fimbriunguis. Later, partly on the basis of a supposed spinneret, it was identified as a spider and named Attercopus fimbriunguis. Further specimens of this species were found, and when examined in detail, along with those assigned to the genus Permarachne, features inconsistent with their placement as spiders were revealed. Silk producing spigots are present, but are borne along the rear edges of ventral plates, not on appendage-like spinnerets, as in spiders. The specimens also have a long, jointed "tail" or flagellum at the end of the abdomen, after the anus, a feature lacking in spiders but present in some other arachnids, such as uropygids.
A 2014 study placed the Uraraneida in the Tetrapulmonata, a clade of arachnids defined by the apomorphy (derived feature) of two pairs of book lungs. The Tetrapulmonata divide into two main clades, one of which, Serikodiastida (Greek for "silk workers"), unites Uraraneida and Araneae (spiders), groups that share the ability to produce and use silk.
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