Ammonite

Tools of time

This is a quite rare ammonite in the Dorset lias, and these specimens are very crushed. However, if they can be identified, then they can be used to date the relative age of the rocks in which they are found. Many ammonites evolved rapidly through time, then they became buried in the rocks as the sediments settled on the sea bed. So the rock layers are a bit like the pages of a book and the ammonites are the changing page numbers. If the same ammonite is found in two different places, then the rocks that they are found in must be the same age.

 

Find out more about ammonites on the molluscs pages.

Common name

Ammonite

Scientific name

Alsatites laqueus

Type

Molluscs > Cephalopods


Strata

Blue Lias

Time period

Lower Jurassic

Age

200 myo

Where found

Seven Rock Point, Lyme Regis

Found by

W.D.Lang

Museum

Lyme Regis Museum

Accession number

L.1973.23