RARE Idiohamites fremonti Heteromorph Fossil Ammonite – Lower Cenomanian, Cretaceous – Fort Worth, Texas – Alice Purnell Collection

Description

Offered for sale is a striking and rare Idiohamites fremonti fossil ammonite, a heteromorph cephalopod from the Lower Cenomanian Stage of the Cretaceous Period, approximately 100 to 94 million years ago. This particular specimen was discovered in Fort Worth, Texas, USA, an area renowned for its fossiliferous Cretaceous marine sediments. The piece originates from the renowned Alice Purnell Collection, noted for its museum-grade fossil curation.

Idiohamites fremonti is part of the family Diplomoceratidae and is characterised by its loosely coiled, irregular shell form—known as “heteromorph”—which sets it apart from the more typical planispiral ammonites. These uncoiled shell forms are thought to have affected the animal’s buoyancy and lifestyle, with some suggesting a vertical orientation in the water column or near-bottom dwelling habits.

This fossil presents excellent preservation, clearly displaying the unique coiling and surface features that define the species. It is a fantastic specimen for both educational and display purposes.

Geological Context: The Lower Cenomanian marks the onset of the Late Cretaceous and was a time of widespread shallow seas across North America. The Fort Worth area is part of the Eagle Ford and Woodbine formations, which are highly productive fossil zones. These marine deposits yield a diverse array of ammonites, bivalves, and other marine life, helping to piece together the paleoecology of the Western Interior Seaway.

Key Details:

• Species: Idiohamites fremonti (Heteromorph Fossil Ammonite)
• Fossil Type: Extinct marine cephalopod
• Age: Lower Cenomanian, Cretaceous (~100–94 million years ago)
• Location Found: Fort Worth, Texas, USA
• Provenance: From the Alice Purnell Collection
• Size: See photo for scale (1cm rule squares / cube included)
• Condition: Excellent structural preservation with visible heteromorph coiling
• Authenticity: 100% genuine specimen with Certificate of Authenticity
• Photo: The exact specimen shown in the listing is what you will receive

Scientific & Collector Value: Idiohamites fremonti is a prime example of heteromorph ammonite evolution and a key fossil for understanding Cretaceous marine environments in North America. Its distinctive form makes it a standout piece for collectors. With provenance from the respected Alice Purnell Collection, this specimen carries both scientific credibility and historic value.

All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.

Fast & Secure Shipping – All fossils are carefully packed and dispatched promptly for safe delivery.

Add a unique and rare piece of American Cretaceous marine history to your collection with this Idiohamites fremonti heteromorph ammonite fossil from Fort Worth, Texas.