Cardioceras praemartini Fossil Ammonite Lower Oxfordian Jurassic Ammonite Dorset UK

Description

Genuine Cardioceras praemartini Ammonite Fossil

This listing is for a Cardioceras praemartini ammonite fossil from the Lower Oxfordian Stage of the Jurassic Period, collected in Dorset, United Kingdom. Dated to around 163–160 million years ago, this specimen is a fine example of the ammonite diversity that thrived in the warm, shallow seas of Jurassic Britain. Each fossil is carefully selected for its scientific and display qualities, and the exact specimen shown in the photographs is the one you will receive. Included with your purchase is a Certificate of Authenticity, guaranteeing it as a 100% genuine piece of natural history.

Geological Context

The Oxfordian Stage marks the base of the Upper Jurassic and is an interval of great importance in European geology. The marine deposits of Dorset are among the most renowned in the world, forming part of the famous Jurassic Coast UNESCO World Heritage Site. Sediments from this period, particularly the Oxford Clay Formation and associated limestone and marl layers, provide exceptional preservation of ammonites and other marine organisms.

Cardioceras praemartini is part of a lineage of ammonites used to define precise biozones within the Oxfordian, making it scientifically significant for both palaeontologists and collectors. Fossils from Dorset are especially prized because of the clarity of preservation and their role in defining Jurassic stratigraphy.

Scientific Classification

• Species: Cardioceras praemartini
• Genus: Cardioceras
• Family: Cardioceratidae
• Superfamily: Stephanoceratoidea
• Order: Ammonitida
• Class: Cephalopoda
• Age: Lower Oxfordian, Jurassic (~163–160 million years ago)
• Locality: Dorset, United Kingdom

Morphological Features

Cardioceras praemartini is recognised for its strongly ribbed, evolute shell, with bold costae radiating outward from the umbilicus and curving across the flanks. The ribs are often sharp and distinctive, giving the shell a strikingly ornate appearance. Its whorls are relatively broad, and the suture lines are intricate, a feature characteristic of Jurassic ammonites.

The species is part of the Cardioceras cordatum group, but exhibits subtle differences in ribbing style and whorl proportions that distinguish it within the evolutionary sequence. These features not only aid identification but also highlight the diversity of ammonite adaptations within Oxfordian seas.

Stratigraphic and Palaeontological Significance

Ammonites of the genus Cardioceras are key index fossils for the Oxfordian Stage, allowing geologists to correlate marine rock layers across Europe with precision. Cardioceras praemartini is especially important for understanding the early Oxfordian ammonite succession, making it a highly valuable specimen for both collectors and scientific reference.

Dorset’s Lower Oxfordian deposits yield excellent examples of this species, often used to refine ammonite zonation schemes. The fossil’s presence in these deposits provides insight into ancient marine ecosystems and the evolutionary development of cephalopods during the Jurassic.

Depositional Environment

During the Lower Oxfordian, Dorset was covered by a shallow, tropical sea, rich in life. Warm waters supported diverse faunal communities, including ammonites, bivalves, brachiopods, marine reptiles, and fish. The fine-grained sediments of the Oxford Clay created an ideal environment for fossil preservation, burying shells quickly and protecting them from erosion or scavenging. Over millions of years, these shells mineralised into the durable fossils we see today.

Collector and Display Value

This Cardioceras praemartini ammonite fossil from Dorset combines historical, scientific, and aesthetic value. With its bold ribbing and elegant coiling, it makes a superb addition to any fossil collection, whether for research, education, or display. Its provenance from the famous Jurassic Coast adds further prestige, linking the specimen directly to one of the world’s most important fossil localities.

• Type: Fossil Ammonite – Cardioceras praemartini
• Age: Lower Oxfordian, Jurassic (~163–160 million years ago)
• Location: Dorset, United Kingdom
• Scale: Rule squares/cube = 1 cm (see photographs for full sizing)
• Authenticity: 100% genuine specimen with Certificate of Authenticity
• Specimen: The exact fossil in the photographs is the one supplied

This ammonite is a rare and authentic piece of Jurassic heritage, offering both beauty and scientific significance. It is a true link to the prehistoric seas that once covered Dorset and a timeless addition to any serious fossil collection.