RARE Thomelites sornayi British Chalk Ammonite Fossil – Cenomanian Cretaceous Eastbourne Sussex UK – Certified Authentic

Description

RARE FOSSIL AMMONITE: THOMELITES SORNAYI

This scientifically significant and beautifully preserved fossil is a Thomelites sornayi ammonite from the Cenomanian stage of the Cretaceous Period, discovered in the iconic British Chalk Formation at Eastbourne, Sussex, United Kingdom.

Sourced from the well-known Alice Purnell Collection, this fossil is not only a collector’s piece but also a scientifically important example of a rare ammonite genus. The photo shows the exact specimen for sale — what you see is what you will receive.

Scale rule squares = 1cm. Please refer to the photo for full sizing and detail.

Fossil Classification & Taxonomy:

• Species: Thomelites sornayi
• Type: Ammonite (planispiral cephalopod mollusc)
• Order: Ammonitida
• Superfamily: Acanthoceratoidea
• Family: Acanthoceratidae
• Subfamily: Acanthoceratinae
• Genus: Thomelites

Geological Context:

• Geological Period: Late Cretaceous
• Stage: Cenomanian (approx. 100.5–93.9 million years ago)
• Formation: Upper Chalk Group (British Chalk Formation)
• Location: Eastbourne, Sussex, United Kingdom
• Depositional Environment: Warm, shallow, epicontinental marine shelf. The British Chalk formed in low-energy environments with abundant planktonic and nektonic life.

Morphology & Notable Features:

Thomelites sornayi is a moderately rare ammonite, distinguishable by its smooth, compressed whorls and fine ornamentation. It exhibits a classic planispiral shell and sometimes faint ribbing or tubercles near the ventrolateral margins. The genus is considered biostratigraphically valuable and is relatively uncommon in British chalk fossil collections.

This specimen provides a clean and sharply preserved example, valuable for both display and study.

Biozone & Scientific Significance:

While not formally designated as a zonal index fossil, Thomelites sornayi occurs in association with other diagnostic Cenomanian taxa and can help refine local biostratigraphy within the Lower to Middle Cenomanian intervals of southern England.

Provenance & Authenticity:

This fossil is part of the respected Alice Purnell Collection, known for careful curation, locality data, and preparation standards. It is a 100% genuine fossil — not a replica or cast — and comes with an official Certificate of Authenticity.

Ideal for collectors, researchers, educators, or anyone seeking a rare piece of Earth’s evolutionary past.