Rare Bostrychoceras indicum Ammonite Fossil Lower Campanian Cretaceous Madagascar Genuine Specimen

Description

This listing is for a rare Bostrychoceras indicum ammonite fossil, an extraordinary heteromorph ammonite from the Lower Campanian stage of the Late Cretaceous Period, approximately 83–80 million years old. Collected from the fossil-rich marine deposits of Menabe, Madagascar, this specimen represents one of the most remarkable ammonites with its unusual shell form, making it both a scientifically important and visually striking fossil.

All of our fossils are 100% genuine specimens and supplied with a Certificate of Authenticity. The exact fossil you see in the photographs is the one you will receive. A 1 cm scale cube and rule squares are included in the photos for precise measurement reference.

Geological Context and Age

This ammonite comes from the Lower Campanian stage of the Late Cretaceous, a period defined by high global sea levels, warm climates, and flourishing marine biodiversity. The Menabe region of western Madagascar was, at this time, part of a shallow marine environment along the margins of the Tethys Ocean. These seas supported diverse ammonite faunas alongside other marine organisms such as belemnites, crustaceans, fish, and marine reptiles.

The Campanian stage is particularly important for palaeontologists because it preserves a wide range of heteromorph ammonites—species with uncoiled or irregular shells that showcase the evolutionary diversity of these extinct cephalopods. Fossils like Bostrychoceras indicum are crucial for stratigraphic studies, helping to define biozones within the Campanian sequence.

Morphology and Distinctive Features

Bostrychoceras indicum is a member of the family Nostoceratidae, within the superfamily Turrilitoidea of the order Ammonitida. This group is characterised by its highly irregular, helically wound, and heteromorphic shells. Unlike the typical tightly coiled ammonites, Bostrychoceras displays an open spiral form, often forming tower-like structures with ribbing along its whorls.

This specimen highlights the genus’ unique helically coiled and ribbed shell morphology. Its ribs are prominent, running across the whorls, and in some cases accentuated by nodes or tubercles. These features provided shell strength and may have influenced buoyancy and locomotion. The heteromorphic form suggests that Bostrychoceras occupied a different ecological role compared to its tightly coiled relatives, possibly drifting in the water column rather than swimming actively.

Scientific Importance

Bostrychoceras indicum is a species of considerable palaeontological interest because it represents the evolutionary experimentation within heteromorph ammonites during the Campanian. Its unusual morphology, distinctive ribbing, and stratigraphic range make it an important index fossil for correlating Campanian deposits.

The species also provides insight into ammonite palaeoecology. The irregular shell structure, while less hydrodynamically efficient for active swimming, suggests a lifestyle adapted to passive drifting or hovering in the mid-water column. This ecological role highlights the adaptability of ammonites and their ability to occupy diverse marine niches.

Collector and Display Value

This rare Bostrychoceras indicum ammonite fossil from Madagascar is a stunning specimen that combines scientific significance with visual appeal. Its distinctive spiral and ribbed morphology make it a captivating display piece, standing out from the more common planispiral ammonites.

Collectors value heteromorph ammonites for their rarity and striking forms, and Bostrychoceras indicum is among the most iconic of these unusual cephalopods. Its provenance from Madagascar, one of the world’s premier fossil localities, enhances its desirability. This specimen is ideal for serious fossil collectors, museum-quality displays, or anyone seeking a unique piece of Earth’s deep-time history.

Your Guarantee of Authenticity

• 100% genuine Bostrychoceras indicum ammonite fossil from Menabe, Madagascar
• Geological age: Lower Campanian, Late Cretaceous (approx. 83–80 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 Bostrychoceras indicum ammonite fossil is a rare and scientifically valuable specimen from Madagascar’s Campanian deposits. Its unusual heteromorph form, striking ribbing, and authentic provenance make it an exceptional addition to any fossil collection.