Complete Acanthodian Devonian Fossil Fish Climatius from Scotland

Description: The Acanthodians are jaw-bearing fish who still are the subject of dispute over their systematic position. They possessed highly-advanced, spindle-shaped bodies thought to have made them swift swimmers. The body was covered in small mosaic-like scales. They possessed small teeth which were typically confined to the lower jaw; some were toothless. The feature they all share in common is the fact that all fins other than the caudal are supported by massive spines formed of dentine. Indeed, the name Acanthodii is derived from the Greek word for spine.

The oldest acanthodian lived during the late Ordovician. They reached their peak during the Devonian, and became extinct during the Great Dying of the end-Permian extinction. This well-preserved example is known as Climatius; the genus died out in the upper Devonian. As is typical, the most prominent feature to be seen here are the diagnostic spines. Climatius had a total of four pairs between the pectoral and pelvic fins, most of which can be seen here.