Dolichopterus is agenus ofprehistoricsea scorpions,arthropods in theorder Eurypterida. Fossils ofDolichopterus have been discovered in deposits ranging from Silurian to Devonian, and have been referred to several different species, some of them of dubious affinity to this genus.^[1]

Dolichopterus Temporal range:Silurian–Devonian PreꞒ Ꞓ O S D C P T J K Pg N
D. macrocheirus fossil,University of Michigan Museum of Natural History
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Order:	†Eurypterida
Family:	†Dolichopteridae
Genus:	†Dolichopterus Hall, 1859
Type species
Dolichopterus macrocheirus Hall, 1859
Other species
?D. asperatusKjellesvig-Waering, 1961 ?D. bulbosusKjellesvig-Waering, 1961 D. gotlandicusKjellesvig-Waering, 1979 ?D. herkimerensisCaster & Kjellesvig-Waering, 1956 D. jewettiCaster & Kjellesvig-Waering, 1956 D. siluricepsClarke & Ruedemann, 1912

It lived in theshelf orepicontinental seas of the region whereAvalonia,Baltica andLaurentia met during theCaledonian orogeny; its fossils have been found in modern-dayNorth America and theBaltic region. They were about 25–30 centimetres (10–12 in) long.

Dolichopteridae, which lived in the Silurian and Devonian periods, had outer surfaces that were either smooth with pustules and semilunar scales. Their compound eyes were arcuate and located anteriorly on the prosoma (head). Their abdomens had epimers (lateral projections). The telson (the posteriormost division of the body) was lanceolate. Their chelicerae were small, and the first three pairs of walking lags were stout, with powerful spines. The last pair of walking lags had supplementary lobes, while the swimming lags had the last joint enlarged, as part of the paddle. The male genital appendage was long.^[2]

Dolichopterus is distinguishable by its nearly smooth outer surface; its subquadrate prosoma (head), and the slightly serrated margins on the distal joints and lobes of the swimming legs.^[2]

• List of eurypterids