What extinct order of arachnids lived from the Silurian to Permian?

What extinct order of arachnids lived from the Silurian to Permian? Trigonotarbida was an extinct arachnid order whose fossils span that interval.

Trigonotarbids looked somewhat like spiders, but they were not true spiders. Their abdomens remained visibly segmented, and they lacked the silk-producing spinnerets found in spiders. Fossils show bodies ranging from a few millimetres to several centimetres, with some later species heavily armoured by spines and tubercles.

The group probably consisted mainly of terrestrial predators that hunted other arthropods. Most known fossils come from Carboniferous coal deposits, although the earliest record is Late Silurian and the youngest extends into the Early Permian. Their fossils have sometimes been confused with harvestmen and other ancient arachnids, making them important for understanding how spider-like body plans evolved. About 70 valid species are currently known.