Fossil Finder Database 2022
This ammonite fragment is important because Caenisites turneri is one of the zonal ammonites for the part of the Lower Lias called Shales-with-Beef. Zonal ammonites can be used to match up layers of sediment found in widely separated areas. Even a small piece of ammonite like this, if identifiable, can be used in this way.
Naming fossils This highly distinctive bivalve shell comes from the Corallian, Upper Jurassic, rocks around Osmington. It’s called Myophorella, but used to be known as Trigonia because of the distinctive triangular shape of the shell. It was reclassified when researchers reviewed the group and this reflects the constant refinements made in science. When it was…
Here is a bed of the ammonite Arnioceras preserved in calcite crystal and iron pyrite. The centres of the ammonites are preserved in calcite but the body chambers (the part of the shell the animal lived in) have been filled in with the pyrite. The local collectors call this ‘Gold Stone’ for obvious reasons. Arnioceras is one…
Good enough to eat? These oysters are similar to the common Gryphaea oysters, but with a much flatter shell. They can grow in great profusion and litter the beaches below Sandsfoot Castle when storms have scoured away the sand along the Portland Harbour Shore. You can tell they are oysters by the finely layered shell.…
Arnioceras are often found in large numbers in certain rock layers, particularly the Arnioceras stone band. They are one of the most common ammonites found locally, and these specimens are very well-preserved.
These are probably worm burrows preserved in the Upper Greensand. They were made when the sands were being laid down in a shallow, warm sea about 100 million years ago.
BMX bike tyre! This knobbly ammonite, Mantelliceras, is the most common and most distinctive fossil found in the Lower Chalk in East Devon. This rock layer is known as the Cenomanian Limestone and spans about six million years. Yet it is only about one metre thick in most places, and as a result, there is…
Tragophylloceras is one of the most commonly found ammonites from the Green Ammonite Beds. This specimen is fairly small, but is beautifully preserved.
Mapping geology This ammonite is an example of Harpocers from the Junction Bed near Seatown. Below is another Harpoceras from the Yorkshire coast near Whitby. As ammonites evolved rapidly, each species only existed for a relatively brief period of time. Therefore the Junction Bed on the Dorset coast and the dark shales near Whitby must…