Ammonite - Fossilised animal - Argonauticas besairiei on...

An exceptional, finely prepared fossil ammonite, identified as the species Argonauticeras besairiei, originates from the limestone deposits of Madagascar. This superb specimen, showcasing the characteristic planispiral coiling of cephalopods, is notable for its intricate and incredibly well-defined ammonitic suture lines, which wrap across the shell's surface. A meticulously polished finish has revealed a rich tapestry of natural mineralization, featuring deep honey and amber yellows, warm tans, and dramatic dark dendritic patterns of brown and black. The central umbilicus remains incredibly detailed and perfectly preserved. This specimen is elegantly mounted on a custom-fitted, sculptural Carrara marble base, which mirrors the fossil's form. It stands as a profound work of natural art and a prized piece for collectors or interior design enthusiasts. ​Scientific Background ​These prehistoric cephalopods were marine animals characterized by an external shell composed mainly of calcium carbonate in the form of aragonite, along with a smaller portion of an organic, protein-based substance (conchiolin). The shell was internally divided by transverse septa into multiple chambers, of which the mollusk occupied only the final and largest one (the living chamber). ​The remaining cavities, which formed the phragmocone (the chambered part of the shell), served as "air chambers" – functionally identical to those of the modern Nautilus. Filled with gas and cameral fluid, they allowed the organism to regulate its hydrostatic buoyancy and control its vertical movement through the water column. ​The pressure and volume of these cameral fluids were regulated by the siphuncle, a thin, vascularized tubular organic structure that was partially mineralized. Passing longitudinally through all the septa, the siphuncle enabled continuous fluid and gas exchange between the animal’s bloodstream and the sealed chambers through an osmotic process. Weight detail Ammonite Argonauticeras besairiei: 10.20 kg Carrara Marble base: 7.30 kg Total: 17.50 kg

Schätzpreis:€3,300

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