Dactylioceras was a widespread genus of ammonites from the Lower Jurassic period,[1] approximately 180 million years ago (mya).

[2] and Like many other ammonites, the genus Dactylioceras is extremely important in biostratigraphy, being a key index fossil for identifying their region of the Jurassic.

Though they eventually died out 180 mya, their style of ribbing was copied by numerous subsequent ammonite genera until the whole group became extinct 66 million years ago with the dinosaurs.

Mass mortality specimens of Dactylioceras are common, and perhaps suggest that these ammonites may often have died shortly after spawning.

[2] In these small but strong shells ribs run straight or are slightly convex across the venter.