Fossil fish (Dapedium punctatus) in rock. Dapedium is a primitive neopterygian ('new fins') species of fish that developed during the late Triassic and Jurassic period (around 200 million years ago). The body was oval or near-circular and the skin was covered with thick, enamel-like scales. The skull was armoured with bony plates and the tail was short and stout, enabling a sudden change in direction whilst swimming. Depending upon species, Dapedium grew to between 9 and 40 centimetres in length.