Home


  Fossils||
  Portsdown||   Echinoids||   Ammonites||   Belemnites||   Bivalves||   Brachiopods||

References

  Glossary

Belemnites

The Belemnites are members [family?] of the extinct order Belemnitada of the class Cephalopoda (subclass Coleoidea).
They are particularly important in the Jurassic and Cretaceous.

The following discussion covers:

Morphology

The belemnite has an internal skeleton, made up of:

  • A phragmocene, (outer shell)
  • Rostrum, (guard) and
  • Pro-ostracum. (inner-shell)

Most fossils of belemnites consist only of the rostrum, the back (posterior) bullet-shaped guard. This guard is a tapering cylinder of radiating calcite needles, and is hollow. Broken specimens show this structure of radiating calcite fibres, and concentric growth lines.
The aragonite phragmocene fits into the anterior end of this hollow.
There was a tongue-like projection from the anterior of the phragmocene, and possibly protected the anterior of the body.

In complete specimens, flattened regions are present at the front (opposite the point) which represent the phragmocene [or maybe the pro-ostracum]

[get a diagram!]

return to top





For any comments, suggestions or contributions, please e-mail me at: portsdown@bbm.me.uk