Brachyopterus is a genus of prehistoric eurypterid

Eurypterid

Eurypterids are an extinct group of arthropods related to arachnids which include the largest known arthropods that ever lived. They are members of the extinct order Eurypterida ; which is the most diverse Paleozoic chelicerate order in terms of species...

 of the family Rhenopteridae

Rhenopteridae

Rhenopteridae are an extinct family of prehistoric eurypterids that lived in the Lower Devonian period in Europe and possibly North America.-Description:...

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Description

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. The abdomen is narrow and ends in a short styliform telson

Telson

The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...

. Brachyopterus date from the Middle Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

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Taxonomy

The genus contains only one species:

• Brachyopterus stubblefieldiStørmer, 1951 — Ordovician, Montgomeryshire