Rare: 6″ Fossil Ammonite Primarietites reynesi | Sinemurian Jurassic | Shepton Mallet UK | Genuine + COA

Description

This listing is for a rare 6″ Fossil Ammonite specimen of Primarietites reynesi, discovered in the Shepton Mallet region of Somerset, United Kingdom. This fossil dates to the Sinemurian Stage of the Lower Jurassic, making it approximately 199–190 million years old.

Scale Rule Squares/Cube = 1cm — for full sizing, please refer to the photograph, which shows the exact specimen you will receive.

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

Fossil & Geological Information:

• Fossil Type: Ammonite
• Species: Primarietites reynesi
• Order: Ammonitida
• Superfamily: Psiloceratoidea
• Family: Arietitidae
• Geological Age: Lower Jurassic
• Stage: Sinemurian
• Biozone (likely): Arietites bucklandi or early Sinemurian zones (exact zone dependent on horizon at Shepton Mallet)
• Formation: Lower Lias Group
• Depositional Environment: Shallow epicontinental marine shelf — soft calcareous muds and silts with low energy conditions
• Location: Shepton Mallet, Somerset, United Kingdom

Morphology & Notable Features:

Primarietites reynesi is a distinguished member of the early Jurassic ammonite faunas, known for:

• Large evolute shell structure — all whorls visible with wide umbilicus
• Strong, widely spaced primary ribs, often bifurcating across flanks
• Prominent keel or ventral ridge
• Bold ornamentation indicative of Arietitidae family features
• The shell is often thick with robust construction, representing a nektonic (free-swimming) lifestyle

This species is a transitional form between earlier psiloceratacean morphologies and more heavily ornamented mid-Jurassic ammonites, marking it as a biostratigraphic marker in early Jurassic sections.

Scientific & Collector Value:

• Primarietites reynesi is less commonly found in complete, display-quality preservation — especially at larger sizes like this 6″ specimen
• Key taxon for understanding ammonite radiation post-End Triassic extinction
• Excellent teaching or research specimen for biozonation and evolutionary studies
• Sourced from a classic British Lower Jurassic fossil locality

What You Get:

• 6″ Primarietites reynesi fossil ammonite
• Certificate of Authenticity
• Carefully packed, tracked shipping
• The actual specimen in the photo — hand-selected for its scientific and visual appeal

This is a standout addition for any fossil collector, geologist, teacher, or museum-quality collection. Don’t miss the opportunity to own a beautifully preserved piece of Jurassic life from Somerset’s fossil-rich strata.