Rare Menuthiocrioceras hourcqui Heteromorph Fossil Ammonite Upper Hauterivian Cretaceous Madagascar Authentic Specimen with COA

Description

This listing is for a rare fossil ammonite, Menuthiocrioceras hourcqui, a distinctive heteromorph ammonite from the Upper Hauterivian stage of the Early Cretaceous (approximately 130–129 million years ago). Collected in Madagascar, this specimen highlights the unusual coiling and ribbing that make heteromorph ammonites both rare and highly prized. The fossil shown in the photographs is the exact piece you will receive. Scale rule squares / cube = 1 cm – please see the photos for precise sizing. Every fossil we supply is 100% genuine and comes with a Certificate of Authenticity.

Geological Context: Upper Hauterivian, Early Cretaceous

The Hauterivian stage is an important subdivision of the Early Cretaceous and is well known for its abundant and diverse ammonite faunas. Madagascar, located along the ancient southern margin of the Tethys Ocean, was covered by shallow tropical seas during this time. Fine marine sediments of limestone and marl accumulated, preserving marine organisms in excellent detail.

Ammonites such as Menuthiocrioceras hourcqui are significant to paleontologists as index fossils, used to date and correlate Hauterivian deposits worldwide. Their rarity and distinct morphology also provide key insights into ammonite evolution and ecological diversity in the Early Cretaceous seas.

The Species: Menuthiocrioceras hourcqui

Menuthiocrioceras hourcqui belongs to the order Ammonitida, superfamily Ancylocerataceae, and family Ancyloceratidae. Unlike the typical tightly coiled planispiral ammonites, heteromorphs such as Menuthiocrioceras developed shells that were irregularly coiled, often with open, crioconic, or hook-like whorls.

The shell of M. hourcqui displays loosely coiled whorls with bold ribbing, giving the fossil a striking appearance. These ribs often cross the flanks prominently, providing structural strength as well as clear taxonomic features. The open and irregular coiling indicates that this ammonite likely had a different ecological niche compared to its planispiral relatives, possibly moving more slowly or drifting in the water column rather than actively swimming.

This adaptation makes heteromorph ammonites like Menuthiocrioceras hourcqui particularly fascinating, as they demonstrate the diversity of ammonite evolution during the Early Cretaceous.

Morphological and Scientific Features

• Order: Ammonitida
• Superfamily: Ancylocerataceae
• Family: Ancyloceratidae
• Genus and Species: Menuthiocrioceras hourcqui
• Geological Stage: Upper Hauterivian, Early Cretaceous (c. 130–129 Ma)
• Locality: Madagascar
• Shell Traits: Heteromorph open coiling, bold ribbing, crioconic to irregularly curved form
• Scientific Importance: Rare heteromorph ammonite, important index fossil and evolutionary marker

The distinctive uncoiled shape and pronounced ornamentation of this ammonite mark it as both a scientifically valuable specimen and a collector’s rarity.

Collector and Display Value

This rare heteromorph ammonite, Menuthiocrioceras hourcqui, is highly desirable among collectors due to its unusual morphology and limited availability. Heteromorph ammonites are far less common than their tightly coiled relatives, and specimens such as this from Madagascar are especially prized for their provenance and preservation.

With its striking coiling, bold ribbing, and scientific importance, this ammonite makes an outstanding display piece. Its origin from Madagascar’s Hauterivian deposits enhances its value, as this region is internationally recognised for yielding exceptional Early Cretaceous fossils.

Every fossil we offer is carefully chosen for authenticity, preservation, and scientific relevance. Supplied with a Certificate of Authenticity, this Menuthiocrioceras hourcqui specimen represents a rare opportunity to own a genuine heteromorph ammonite from the Early Cretaceous seas of Madagascar.