Fossil of Gyrodus circularis, an extinct genus of a pycnodont bony fish that evolved in the late Triassic period and lived on throughout the Jurassic and Cretaceous periods. Their habitat was shallow marine, but they may also have lived in sweet waters. They belonged to the order of Pycnodontiformes that is now extinct, disappearing during the Eocene epoch. Fossils have been found in rock formations worldwide. This specimen, actual length 40 cm, is from the Solnhofen limestones of Bavaria, southern Germany.