Complete Acanthodian Fossil Fish From The Devonian Of Scotland

Ischnacanthus gracilis

Class Acanthodii, Order Ischnacanthiformes

Geological Time: Lower Devonian

Size: 95 mm in length on 118 mm by 78 mm matrix

Fossil Site: Tillywhandland Quarry, Forfar, Scotland

Description: The Acanthodians are jaw-bearing fish who still are the subject of dispute over their systematic position. They possess highly advanced, spindle-shaped bodies thought to have made them swift swimmers. The body was covered in small mosaic-like scales. They Ischnacanthuspossessed 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 Ordovicain. 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 Ischnacanthus; the genus derives its name from the thinner spines it possessed. The ischnacanthids lived from Late Silurian to Late Carboniferous time, and have been found in both freshwater and saltwater deposits.

All the diagnostic features of the taxon are displayed within this high-quality specimen which has recently been obtained from a 50 year old collection.

click to enlarge fossil pictures

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