Ammonite

Department of Earth Sciences’ Geology Museum

Ammonite

This is the ‘holotype’ of the ammonite species Procerites twinhoensis Arkell: the specimen that W. J. Arkell designated as typifying the species that he established in his (1951-8) publication on British Bathonian Ammonites. The specimen is from the Twinhoe Ironshot Oolite, a mid-Jurassic horizon exposed in a quarry at Twinhoe Green, near Wellow, Somerset. It is preserved as an internal mould (the filling of sediment inside the fossil, rather than the shell itself), and encrusted by small fossil oyster shells and worm tubes. It has been painted to show up the intricate pattern of the septal sutures which help to distinguish ammonite species.

  • Item reference: BRSUG 13487
  • Photographer: Simon Powell
  • Copyright: Department of Earth Sciences, University of Bristol
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