Lytoceras sp. (fimbriatum?) Preparation

Lytoceras sp. (fimbriatum?)

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I have just finished preparing this large and rare Lytoceras ammonite from the Jurassic green ammonite beds of Dorset.

It was found by the experienced local professional fossiler David Halmkin, who has only found one other Lytoceras of this size in the 20 years he has been collecting from the green ammonite beds, which shows their rarity.

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This specimen measures 22 cm at its widest point and has been prepared with the delicate flanges intact. The rare inclusion of the termination on this ammonite is also preserved. This is where the lines of the ammonite become compacted near the entrance / mouth border. This is a very fragile part of the ammonite and is often lost during preservation.

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Attached to the fossil through fossilisation is a juvenile Liparoceras ammonite which seems to have been skewered by one of the Lytoceras ammonite flanges, perhaps when the larger ammonite landed on top of it on the sea floor.

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W.D Lang reported the Lytoceras ammonite as being absent from the green ammonite beds, having noted it only being present as far up as the Belenmite marl, when he wrote his papers on the lower lias ammonites in the 1900’s.

Below are a couple of photos during preparation showing the delicate flanges being exposed. Great care has to be taken as they are paper thin in places and semi-translucent as a result. They are best left with a supporting wall of matrix until the end of the preparation to help protect them. Once one side of a flange has been exposed it is important to paint it with thin superglue so that the opposite side can be revealed.

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The red area below shows the restoration to the keel of the ammonite, this area was crushed on the underside.

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The same area showing the restoration can be seen in the below image.