Rare Crioceratites crishnae Heteromorph Fossil Ammonite Barremian Cretaceous Basse Alpes France Authentic Collector Specimen with COA

Description

This listing is for a rare fossil ammonite, Crioceratites crishnae, a heteromorph species from the Barremian stage of the Early Cretaceous (approximately 129–125 million years ago). Found in the Basse Alpes region of France, this ammonite represents a striking example of the heteromorph lineage, displaying the open, loosely coiled shell form that makes these ammonites so distinctive. The photographs show the exact specimen you will receive. Scale rule squares / cube = 1 cm – please see photos for accurate sizing. All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity.

Geological Context: Barremian, Early Cretaceous

The Barremian stage marks an important interval of the Early Cretaceous, during which ammonites flourished in diverse marine environments. At this time, the Basse Alpes of southeastern France formed part of the shallow seas fringing the northern Tethys Ocean. These seas deposited rich sequences of marl and limestone that preserved an outstanding fossil record, including many rare heteromorph ammonites.

Ammonites from this stage, such as Crioceratites crishnae, are considered vital index fossils, used by geologists to precisely date and correlate Barremian marine deposits. Their unusual morphology also provides insights into ammonite adaptation and evolutionary experimentation.

The Species: Crioceratites crishnae

Crioceratites crishnae belongs to the order Ammonitida, superfamily Ancylocerataceae, and family Ancyloceratidae. Unlike planispiral ammonites that display tight, symmetrical coiling, heteromorph ammonites like Crioceratites evolved loosely coiled or crioconic shells, with whorls that remain open and separated.

The shell of C. crishnae is marked by robust ribbing that extends across the whorls, creating a bold, textured appearance. Some specimens may also show tuberculate features, adding to their distinctive morphology. The open coiling suggests a different mode of life from tightly coiled ammonites, with heteromorphs possibly drifting or hovering in the water column rather than swimming actively.

This unusual morphology makes Crioceratites crishnae a key species in the study of ammonite evolution, demonstrating the adaptability of the group during the Early Cretaceous seas.

Morphological and Scientific Features

• Order: Ammonitida
• Superfamily: Ancylocerataceae
• Family: Ancyloceratidae
• Genus and Species: Crioceratites crishnae
• Geological Stage: Barremian, Early Cretaceous (c. 129–125 Ma)
• Locality: Basse Alpes, France
• Shell Traits: Loosely coiled crioconic form, strong ribbing, distinctive open whorls
• Scientific Importance: Index fossil for Barremian deposits, significant in heteromorph ammonite evolutionary studies

Collector and Display Value

Heteromorph ammonites are considerably rarer than their tightly coiled relatives, and Crioceratites crishnae is a particularly desirable species due to its striking open shell form. The ribbed ornamentation enhances both its scientific significance and visual appeal, making it a favourite among fossil collectors.

Provenance from the Basse Alpes region of France, a locality well known for yielding exceptional Early Cretaceous fossils, adds further prestige and collector value. Specimens from this region are highly regarded by paleontologists and collectors worldwide.

This specimen is supplied with a Certificate of Authenticity, ensuring its provenance and authenticity. A rare opportunity to acquire a genuine Crioceratites crishnae heteromorph ammonite from the Barremian stage, it is both a scientifically important fossil and a striking natural display piece.