Brachyopterus

Brachyopterus is a genus of prehistoric eurypterid of the family Rhenopteridae.

It is one of the earliest known eurypterids,[1] having been recovered from Middle Ordovician deposits in Montgomeryshire, Wales.

[2] Brachyopterus is distinguished by its small size, compound eyes with axes converging anteriorly on a subtrapezoid to subpentagonal prosoma (head).

All of its legs are walking legs; the first three pairs are short with spines, except when modified into clasping organs; the last two pairs are moderately long, keeled and tapering in width to terminal claws.

The last leg falls short of the penultimate abdominal segment.

Size comparison of B. stubblefieldi with a human hand.