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Arnioceras Semicostatum Block 190mm


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An Important British Ammonite commune ammonite boulder containing twenty two ammonites now beautifully conserved by many hours of technical skill preparing the ammonoids shells sympathetically away from the surrounding matrix (fossil limestone seabed). The highly skilled work has produced a unique and aesthetically pleasing naturally formed curiosity half boulder. Read the fuller report below...

Genus: Arnioceras semicostatum ammonite commune block.
Origin: Robin Hoods Bay, Whitby, North Yorkshire, England.
Geological location: Lower Sinemurian Lias, semicostatum zone, (described by Young and Bird)
Geological Age: Mesozoic era, early Jurassic, approximately 199 to 191 million years ago.

Block measurements.
Height: 19.0 cm
Width: 14.5 cm
Depth: 6.5 cm

Arnioceras (largest) measurement.
Diameter: 3.5 cm
Depth: 0.8 cm

Approximate overall weight: 1.657 Kg

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The ammonite block is a fascinating study specimen while also having much aesthetic charm. The naturalistically positioned ammonites contained in the original limestone boulder, this polished verso to a smooth tactile finish. The boulder a sea washed block was once the fine muds of the Jurassic seabed, now transformed into limestone. Discovering an ammonite block of this calibre, completeness and size is an rare event. Add to this the quality of the preparation of this uncommon specimen and you have a highly collectable British fossil commune block. Exhibiting excellent preservation to each specimen ammonoid shell, along with attractive colour with calcite variations which have developed within the cephalopods shell and fossilised over millions of years, providing an interesting insight into the internal morphology of the specie. All these factors put this ammonite in a top bracket of discoveries of this type.

Revitalising these fascinating, extinct marine animals phragmacones (exoskeleton-shell) and presenting them in a dramatic way, makes them perfect for collectors or interior designers. Ammonites are becoming increasingly more difficult to gain, particularly the best of the best, from the fossiliferous coasts of the United Kingdom. Our shores may crumble inexorably towards the sea, creating landfalls and new opportunities for collecting, however these types of rarity and quality remain in short supply. Laborious collecting and preparation techniques make the extraction arduous and time consuming, an all too common fact of fossil collection today in an ever developing and changing environment of Britain.

Additional Information

Age Jurassic
Origin England