RARE Caloceras intermedium Fossil Ammonite | Hettangian Jurassic Waterloo Larne Northern Ireland | Authentic

Description

This listing features a RARE and scientifically significant specimen of the ammonite Caloceras intermedium, originating from the renowned Waterloo Formation near Larne, County Antrim, Northern Ireland. This fossil is from the Lower Hettangian Stage of the Early Jurassic period, specifically within the Planorbis Zone, Johnstoni Subzone—a key interval used in global biostratigraphic correlation.

Geological & Taxonomic Information:

• Fossil Type: Ammonite (extinct marine cephalopod)
• Species: Caloceras intermedium
• Order: Ammonitida
• Superfamily: Psiloceratoidea
• Family: Psiloceratidae
• Geological Stage: Lower Hettangian, Jurassic
• Age: Approx. 201.3 to 199.5 million years ago
• Formation: Waterloo Mudstone Formation
• Biozone: Planorbis Zone
• Subzone: Johnstoni Subzone
• Location: Waterloo, Larne, County Antrim, Northern Ireland
• Depositional Environment: Shallow marine shelf with predominantly fine-grained mudstone sedimentation, indicative of early post-extinction marine recovery

Stratigraphic & Scientific Significance: Caloceras intermedium is a zonal ammonite with strong bio-stratigraphic value, helping define the lower boundary of the Jurassic System. The Planorbis Zone is critical in identifying the Triassic-Jurassic boundary and the subsequent biological recovery.

Morphological Features:

• Moderately involute shell with rounded whorls
• Faint ribbing with smoother shell ornamentation compared to related species
• Evolute coiling with shallow umbilicus
• Excellent preservation typical of Waterloo Formation nodules

Notable Information: Ammonites from the Larne Basin are highly valued by collectors and researchers due to their clarity, rarity, and geological importance. Specimens from the Waterloo Mudstone Formation are especially renowned for their association with the earliest Jurassic ammonite faunas.

Specimen Information:

• Fossil Origin: Waterloo, Larne, Antrim, Northern Ireland
• Scale: Scale rule squares/cube = 1cm. Please refer to the photo for full sizing.
• Condition: Excellent preservation; a carefully selected and stable specimen
• Photo: The image shows the exact specimen you will receive

Certification & Authenticity: All of our fossils are 100% genuine and come with a Certificate of Authenticity. Each fossil is hand-selected for quality, scientific merit, and natural beauty.

This Caloceras intermedium is a rare and valuable ammonite ideal for collectors, educators, or natural history enthusiasts looking to acquire a key fossil from one of the earliest chapters in Jurassic marine life evolution.