- Origin: South Dakota, USA
- Size: H20cm W44cm D40cm
- Weight: 38 Kg
- Description: This exceptional ammonite specimen displays an intense red opal-like iridescence colour on both sides; fused with occasional flashes of green and golden yellow. During the fossilisation process, the natural nacreous shelllayer was transformed chemically, resulting in a play of vivid colour.
- Additional information:
- Sphenodiscus is an extinct genus of acanthoceratacean ammonite. The genus has been found from many continents and is thought to have had a large global distribution during the Maastrichtian stage of the Late Cretaceous. It was one of the last ammonoids to have evolved before the entire subclass became extinct at the end of the period during the Cretaceous–Paleogene extinction event.
- The ammonites are a group of molluscs that lived in the seas from the mid-Devonian (approximately 400 million years ago) to the end of the Cretaceous (65 million years ago). The sequence of events that famously killed off the dinosaurs also drove the ammonites to extinction.