화석명 : 암모나이트 화석
학명 : Pleuroceras spinatum
원산지 : Untersteurmig, Germany
시대 : Jurassic (Lower Lias)
Size : 10cm * 9cm
A superb example of the ammonite Pleuroceras spinatum of the Lower Lias (200 m.y.a) deposits of Germany, this one looks more like a bronze sculpture than the remnants of a living organism. The environment was anoxic, leading to formation of Iron Pyrite (Fool’s Gold). This one is essentially solid pyrite, with only the intricate suturing pattern that gave strength to the shell for minimum weight highlighted in a delicate white tracery. The ridge along the dorsal edge is the remnant of the siphuncule, the means by which the ammonite “shifted ballast” in order to rise and fall in the water column. This most artistic specimen would make a fine addition to any ammonite collection.