Uraloceras Permian Ammonite from Kazakhstan

These patterns are evidenced on the exterior of the shell as sutures. The Ammonidea have a rich evolutionary history which began in the Upper Silurian/Lower Devonian. The order began an extensive radiation in the Triassic and Jurassic, and became most diverse during the Cretaceous, only to become extinct during the late Cretaceous extinction event which also saw the demise of the non-avian dinosaurs. The Goniatite forms became extinct during the Permian. This one is what is termed an index fossil, and is an important biostratigrahic marker for the Lower Permian. The genus is known from pretty much all of Northern Pamgaea.