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.Sepkoski, Jack Sepkoski's Online Genus Database – Cephalopoda
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.Discover Yale
References
P. E. BARTOK, O. RENZ and G.E.G. WESTERMANN The Siquisique ophiolites, Northern Lara State, Venezuela: A discussion on their Middle Jurassic ammonites and tectonic implications
External links UK Fossils