Skirroceras macrum
Skirroceras macrum is a Stephanoceratacean (ammonite) species belonging to the family Stephanoceratidae.

These fast-moving nektonic carnivores lived during the Jurassic period, in the Bajocian age.

Description
Skirroceras macrum has an evolute shell reaching about  of diameter. These ammonites are heavily ribbed, with characteristic nodes.

Distribution
Fossils of Skirroceras macrum are found in the Middle Jurassic Bajocian age marine strata of England and France.