Dapedium

Dapedium is an extinct genus of primitive neopterygian ray-finned fish. The first-described finding was an example of "D. politum", found in the Lower Lias of Lyme Regis, on the Jurassic Coast of England (Leach 1822). "Dapedium" lived in the late Triassic and Jurassic periods.
Appearance.
The various species of "Dapedium" ranged from long, and all had an oval to near-circular body. The skin was covered with thick, rhomboid, ganoid (enamel-like) scales. The smallest species so far found is "D. noricum".
The skull was armoured with bony dermal plates, which were especially plentiful in the orbital region. These bones bore irregular tubercles. The small pectoral and pelvic fins, along with the extended dorsal and anal fins formed a functional unit with the tail. The tail was short and stout, providing the power for a sudden change in direction while the fish was swimming.
The upper jaw of "Dapedium" was moveable and could protrude from the mouth, enabling a wider gape to capture larger prey.
Distribution.
"Dapedium" lived mostly in the Jurassic seas of Europe, a peripheral continental shelf sea of the Tethys Ocean. Notable finds have been made in Holzmaden, Germany, in Temple Grafton, Warwickshire, England and in Lyme Regis, Dorset, England.
Behaviour.
The strong and pointed dentition suggests that "Dapedium" was durophagous, feeding on hard-shelled invertebrates, like mussels and sea urchins.