Dactyiloceras species of Ammonite specimen from Germany is in a shale matrix. the matrix has many more fossils impressions. Dactylioceras are generally small, averaging 2 inches in diameter. They have a strong, ribbed shell. The ribs are slightly inclined forward, running over the outer edge, and either simple or forking at outer end. Though they eventually died out 180 million years ago, their style of ribbing was copied by numerous subsequent ammonite genera until the whole group became extinct 66 million years ago with the dinosaurs.