Rare Eubostrychoceras indopacificum Heteromorph Ammonite Fossil Coniacian Cretaceous Madagascar

Description

This listing is for a rare Eubostrychoceras indopacificum heteromorph ammonite fossil, dating from the Coniacian stage of the Late Cretaceous Period, approximately 89–86 million years ago. Sourced from the renowned fossil beds of Madagascar, this ammonite represents one of the most unusual and scientifically important examples of heteromorph ammonites, known for their uncoiled and irregular shell forms. Its rarity, provenance, and striking appearance make it an exceptional specimen for collectors, museums, and educational displays.

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity. The photographs show the exact specimen you will receive, with a 1 cm scale cube and rule squares included for precise sizing. Please refer to the images for full details.

Geological Context and Age

This ammonite originates from the Coniacian stage of the Late Cretaceous, a period when global sea levels were exceptionally high, submerging much of Madagascar beneath warm shallow seas. These seas were part of the southern Tethyan realm, a biodiversity hotspot that supported an abundance of ammonites, belemnites, marine reptiles, and early teleost fish.

The Coniacian is a crucial interval in Cretaceous stratigraphy, recording significant evolutionary diversification among heteromorph ammonites. Fossils like Eubostrychoceras indopacificum provide vital reference points for establishing biozones, which help geologists correlate rock layers across vast geographic regions. Madagascar’s deposits are particularly renowned for their excellent preservation, producing ammonite fossils with fine morphological detail.

Morphology and Distinctive Features

Eubostrychoceras indopacificum belongs to the family Nostoceratidae, within the superfamily Turrilitoidea of the order Ammonitida. Unlike the typical tightly coiled planispiral ammonites, this heteromorph genus developed an open, helically twisted or irregularly uncoiled shell. These elongated, tower-like shells often exhibit ribbing and surface ornamentation, enhancing their structural strength while creating a highly distinctive appearance.

This specimen clearly displays the helically coiled morphology, with ribbing visible across the whorls. Such heteromorphic designs have long fascinated palaeontologists, as they represent evolutionary experimentation within ammonites. Their unusual shape suggests that Eubostrychoceras may have lived differently from its planispiral relatives—likely slower moving, perhaps drifting in the water column, feeding on plankton or small nekton.

Scientific Importance

Heteromorph ammonites like Eubostrychoceras indopacificum are of great scientific significance because they highlight the diversity and adaptability of ammonites during the Late Cretaceous. Their distinctive morphology, combined with their stratigraphic range, makes them excellent index fossils for the Coniacian stage.

The genus is particularly important in documenting the expansion of heteromorph ammonites across the Tethyan oceans, showing their global distribution and evolutionary innovations. Fossils from Madagascar are key to these studies, as they preserve diagnostic features that allow for precise taxonomic identification and stratigraphic placement.

Collector and Display Value

This rare Eubostrychoceras indopacificum ammonite fossil is highly prized by fossil collectors due to its unusual heteromorph shell form, excellent preservation, and Madagascan origin. Its unique morphology makes it stand out from the more common planispiral ammonites, offering a striking and highly decorative display piece.

For collectors, its rarity and scientific importance add significant value. For educators and museums, it provides a fascinating teaching tool to illustrate the diversity of ammonites during the Late Cretaceous and the evolutionary experiments of nature.

Your Guarantee of Authenticity

• 100% genuine Eubostrychoceras indopacificum ammonite fossil from Madagascar
• Geological age: Coniacian stage, Late Cretaceous (approx. 89–86 million years old)
• Supplied with a Certificate of Authenticity
• Exact specimen shown in photographs (no stock images used)
• Scale cube and rule squares = 1 cm (see photos for accurate sizing)

This Eubostrychoceras indopacificum heteromorph ammonite fossil is a rare and scientifically valuable specimen from Madagascar’s world-famous Cretaceous deposits. Its unique morphology, rarity, and authentic provenance make it an exceptional addition to any fossil collection.