Rare Cardioceras praecordatum Fossil Ammonite Upper Oxford Clay Mariae Zone Oxfordian Jurassic England

Description

This is a rare and scientifically significant Cardioceras praecordatum ammonite fossil from the Upper Oxford Clay, Mariae Zone, Oxfordian stage of the Jurassic period (around 160 million years ago). It was discovered at the historic Warboys Clay Pit in Peterborough, Cambridgeshire, England, a locality renowned for its exceptional preservation of Jurassic marine life. The specimen displays the distinct ribbing and compressed shell form that define this species, making it a highly sought-after piece among both collectors and palaeontologists. The photographs show the actual specimen you will receive, with a 1 cm scale cube for reference. Every specimen is 100% genuine and comes with a Certificate of Authenticity.

Geological Context

The Oxfordian stage marks the beginning of the Upper Jurassic and is of immense importance in global stratigraphy. The Upper Oxford Clay Formation of Cambridgeshire is especially rich in ammonites, with Cardioceras being one of its most diagnostic genera. This specimen comes from the Mariae Zone, a well-defined biozone named after Cardioceras mariae, used extensively for biostratigraphic correlation across Europe.

During the Oxfordian, the Peterborough area was part of a shallow marine environment on the edge of the Anglo-Paris Basin. Fine-grained silty clays settled on the seabed, creating an oxygen-poor depositional setting ideal for fossil preservation. Ammonites such as Cardioceras praecordatum thrived as nektonic predators in these Jurassic seas, leaving behind beautifully preserved shells that today are invaluable both scientifically and aesthetically.

Morphological Features

This specimen of Cardioceras praecordatum exhibits key features typical of the genus:

• Shell Shape: Involute, compressed whorls with a narrow umbilicus.
• Ribbing: Strong, radial ribs extend across the flanks, often bifurcating toward the outer whorl.
• Keel: A pronounced keel along the venter, providing hydrodynamic efficiency in life.
• Whorl Section: Sub-rectangular to compressed, with clear ornamentation.
• Suture Lines: Complex suture patterns, indicative of evolutionary advancement among Jurassic ammonites.

The sharp ribbing and preserved keel highlight its role as an active swimmer and predator, adapted to the mid-water column of Jurassic seas.

Collector and Scientific Importance

Cardioceras praecordatum is a rare ammonite species, and specimens from Warboys Clay Pit are particularly prized due to the site’s historic importance in British palaeontology. For collectors, this fossil represents:

• A rare ammonite species from a classic UK locality.
• A valuable stratigraphic marker, tied to the Mariae Zone of the Oxfordian.
• A scientifically significant specimen for understanding ammonite diversity and evolution.
• A visually striking piece of natural history, with strong ribbing and excellent preservation.

Its rarity ensures that it appeals not only to private collectors but also to academic and educational collections.

Key Details

• Species: Cardioceras praecordatum
• Age: Jurassic, Oxfordian Stage (~160 million years old)
• Biozone: Mariae Zone
• Formation: Upper Oxford Clay
• Location: Warboys Clay Pit, Peterborough, Cambridgeshire, England
• Order: Ammonitida
• Superfamily: Perisphinctoidea
• Family: Cardioceratidae
• Features: Strong ribbing, compressed whorls, keel, complex sutures
• Authenticity: 100% genuine specimen with Certificate of Authenticity
• Scale: 1 cm cube visible in photographs for accurate sizing

This rare Cardioceras praecordatum ammonite fossil from the Oxford Clay of Peterborough is both a scientifically important specimen and a striking natural display piece. With its strong ribbing and connection to the Mariae Zone, it represents a remarkable example of Jurassic marine life and a valuable addition to any fossil collection.

Scale cube = 1 cm. Please see photos for full sizing.