Diplacanthus longispinus Agassiz
Medium sized to large acanthodian. Spines are very long and straight. They are deeply inserted in the body. Since the spines were, compared to the size of the fish, moderately strong, it was eaten by the bigger fish in the lake like Glyptolepis.
The fish is very rare in the Sandwick Fish Bed and can be found elsewhere on Orkney only as loose spines. Between the pectoral spines are two small spines that are positioned flat along the ventral side of the fish. These spines are called the anterior intermediate spines. A bit further on the ventral site towards the pelvic spines another two spines are found called the posterior spines.
The first are not visible on the drawing and also not well known however the shoulder girdle can be roughly compared with Diplacanthus crassisimus