Ammonite species from the "MAASTRICHTIAN" stage (2 entries found)

The juvenile whorls form a tightly coiled helical spire covered with a fine ribbing. The body chamber then rolls away from the juvenile whorls before turning back towards them in a 'U' turn. The ribbing gets stronger on the body chamber. The aperture of the body chamber is right underneath the spire... [view details for full description]

Sphenodiscus is highly involute with an extremely compressed whorl section. The surface of the shell is smooth and the venter is very sharp. The suture pattern is complex with many lobes and saddles.