Rare Mariella lewesensis Heteromorph Fossil Ammonite Cenomanian Cretaceous Southerham UK with COA

Description

Rare Mariella lewesensis Heteromorph Ammonite from Southerham

This listing is for a rare Mariella lewesensis heteromorph fossil ammonite, discovered at Southerham, United Kingdom, within the Cenomanian Stage of the Cretaceous Period. Dating back approximately 100–94 million years, this unusual ammonite represents one of the distinctive heteromorph forms that evolved during the mid-Cretaceous seas. Unlike the typical coiled ammonites, heteromorphs such as Mariella display irregular shell coiling, making them especially striking and scientifically significant fossils.

Every fossil we supply is a 100% genuine specimen and comes with a Certificate of Authenticity. The photographs show the actual piece you will receive, with a 1cm scale cube and rule squares included for accurate sizing.

Geological Age and Locality

This ammonite originates from the Cenomanian Stage, the earliest stage of the Late Cretaceous. During this time, high global sea levels created widespread shallow marine environments across Europe, with conditions that supported abundant marine life.

The Southerham deposits in the UK are renowned for producing a rich variety of ammonites and other marine fossils. These exposures are an important reference point in British palaeontology, providing key insights into the marine ecosystems of the Cenomanian seas. Fossils from this site are increasingly rare, making well-preserved examples highly collectible.

Fossil Type and Scientific Classification

• Genus: Mariella
• Species: Mariella lewesensis
• Order: Ammonitida
• Superfamily: Turrilitoidea
• Family: Turrilitidae

Mariella lewesensis is a distinctive heteromorph ammonite, known for its irregular shell coiling and ribbed ornamentation. This species has been used as an important index fossil for dating Cenomanian deposits in southern England. Its unique morphology sets it apart from more common planispiral ammonites, illustrating the evolutionary experimentation of Cretaceous cephalopods.

Morphological Features

The shell of Mariella lewesensis displays the unusual heteromorph form that defines its genus:

• Uncoiled Growth: Instead of forming a neat spiral, the shell grows in a loosely helicoidal or irregularly coiled form.
• Ribbed Ornamentation: Strong ribs run across the shell surface, often forming a distinctive sculptural appearance.
• Tuberculation: Small tubercles may occur along rib intersections, adding further diagnostic traits.
• Unique Geometry: The irregular shell shape made these ammonites less streamlined, suggesting they occupied a different ecological niche compared to standard coiled ammonites.

These morphological features make heteromorph ammonites like Mariella some of the most visually striking fossils from the Cretaceous seas.

Scientific and Collector Importance

Mariella lewesensis is of major stratigraphic importance, being used to define ammonite biozones within the Cenomanian Stage. Its distinctive form makes it easily identifiable, and its presence is used by geologists to correlate rock layers across different regions of southern England and beyond.

For collectors, specimens of Mariella lewesensis are highly sought after due to their rarity and unusual appearance. Fossils from Southerham are particularly desirable, both for their provenance and for their contribution to the historical record of British palaeontology.

Display and Educational Value

This specimen has been carefully chosen for its diagnostic features and well-preserved detail, making it ideal for display in a collection cabinet or educational setting. Its irregular heteromorph form captures attention immediately, serving as a fascinating teaching specimen for illustrating ammonite diversity and evolutionary adaptation.

Owning a rare Mariella lewesensis heteromorph ammonite from Southerham offers not only an aesthetically striking addition to a collection but also a scientifically important fossil that embodies the unique evolutionary experiments of the Cretaceous seas. This is a one-of-a-kind specimen that brings together natural history, geology, and artistry in a single remarkable fossil.