Rhadinacanthus longispinus Agassiz

Rhadinacanthus longispinus (model by P.H. de Buisonjé)

Drawing from Woodward (1891) catalogue of the fossil fishes in the British museum

Reconstruction (after Burrow at al. 2016)

A medium to large sized acanthodian. The spines are very long and straight and they are deeply inserted in the body. Since the spines were moderately strong (compared to the size of the fish) 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 along the ventral side towards the pelvic spines are another two spines, which are called the posterior intermediate spines. The first intermediate spines are not visible on the drawing and also not well known, however, the shoulder girdle can be roughly compared with Diplacanthus crassisimus

Specimen from the Moray Firth, Collection NMS ©

Specimen from the Sandwick Fishbed, collection NMS ©

Drawing of specimen (after Miller, 1841)

Dorsal fin spine of Rhadinacanthus longispinus.