Palaeospondylus

Palaeospondylus gunni ("Gunn's Ancient Vertebrae") is a mysterious, fish-like fossil vertebrate. Its fossils are described from Achannaras slate quarry in Caithness, Scotland.

The fossil as preserved is carbonized, and indicates an eel-shaped animal of up to 6 centimetres (2 in) in length. The skull, which must have consisted of hardened cartilage, exhibits pairs of nasal and auditory capsules, with a gill-apparatus below its hinder part, but no indications of ordinary jaws.