Lot 118
118
TWO RARE HORNED HETEROMORPH AMMONITES
TWO RARE HORNED HETEROMORPH AMMONITES
TWO RARE HORNED HETEROMORPH AMMONITES
TWO RARE HORNED HETEROMORPH AMMONITES
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These lots have been imported from outside the EU … Read more
TWO RARE HORNED HETEROMORPH AMMONITES

SOUTH DAKOTA

Details
TWO RARE HORNED HETEROMORPH AMMONITES
SOUTH DAKOTA
From the Upper Campanian, Cretaceous (circa 72 million years ago) the specimens of Didymoceras cheyennense supported on block of the original matrix with geodic caverns.
9in. (23cm.)
Special notice
These lots have been imported from outside the EU for sale using a Temporary Import regime. Import VAT is payable (at 5%) on the Hammer price. VAT is also payable (at 20%) on the buyer’s Premium on a VAT inclusive basis. When a buyer of such a lot has registered an EU address but wishes to export the lot or complete the import into another EU country, he must advise Christie's immediately after the auction.

Lot Essay

This very rare and uncoiled ammonite is "among the most striking and remarkable natural objects known from the Cretaceous rocks of the U.S. Western Interior". The species was first described by 1856, and has been subsequently revised to Nostoceras monotuberculatum in 2000. The helical shape with looped tapering finial has provided much debate for palaeontologists as it would not have made an efficient swimmer, and the three different orientations of coiling would present different challenges to the mollusc living inside the shell as they changed the direction of growth.

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