Zugodactylites braunianum Ammonite
Jurassic Period (201.3-145 Million Years Ago)
Zugodactylites is an extinct genus of cephalopods belonging to the Ammonite subclass. It has lived during lower Jurassic, lower Toarcian, ammonite zone Fibulatum. Its fossils were found in Europe, Russia and Canada. Whorl section of shells belonging these ammonites were compressed, equidimensional or depressed. Before aperture of adult shell, there has been collar and constriction. Ribs were dense and they were bifurcating at sharp ventrolateral tubercules or spines. There were no fibulate ribs. Sexual dimorphism is known, and Gabillytes, synonym of Zugodactylites were microconchs. They have evolved from finely ribbed Peronoceras.