Ammonite

This ammonite is the zonal marker for the Semicostatum Zone of the Lower Sinemurian stage of the Lower Lias. When young, this species has relatively little shell ornament. In older specimens the ribbing is much coarser, making this ammonite easy to identify.

Find out more about ammonites on the molluscs pages.

Common name

Ammonite

Scientific name

Arnioceras semicostatum

Type

Molluscs > Cephalopods


Strata

Shales with beef

Time period

Lower Jurassic

Age

200 million years

Where found

Lyme Regis area

Found by

Chris Moore

Museum

Lyme Regis Museum

Accession number

L.1999.3.2