Stephanoceras (meaning crown horn) is an extinct genus of Stephanoceratoid ammonite which lived during the Bajocian (Middle Jurassic).

Ammonites humphriesianum J. de C. Sowerby, 1825,[2] subsequent designation by Buchman, 1898[3] [4][5] Stephanoceras has an evolute shell, as characteristic of the family, with well-developed ribbing and tubercles.

Turbercles, elevated projections, form at the ends of the primary ribs where they bifurcate or sometimes trifurcate.

The primary difference lies in the aperture, which in the microconch has planar extensions on either side, lappets.

Fossils of Stephanoceras are found in the Jurassic marine strata of Canada, Mexico, Saudi Arabia and Spain.