RARE Spiroceras bifurcati Heteromorph Ammonite & Cenoceras inornatum Nautilus Fossils Jurassic Dorset COA

Description

A truly exceptional and rare paired fossil specimen, this multi-block features the co-preservation of a heteromorph ammonite, Spiroceras bifurcati, alongside a Jurassic nautilus, Cenoceras inornatum. It was discovered by our own team members, Alister and Alison, on 30 April 2025 at the world-renowned Jurassic Coast near Burton Bradstock, Dorset, UK.

This remarkable fossil combination comes from the Inferior Oolite Formation, a Middle Jurassic unit famous for beautifully preserved marine life.

Species Overview:

• Spiroceras bifurcati: A rare heteromorph ammonite with a distinct open-coiling or spiral morphology, unlike the typical planispiral ammonites. Its shell features bifurcating ribs and irregular coiling, a defining characteristic of heteromorph taxa.
• Order: Ammonitida
• Superfamily: Stephanoceratoidea
• Family: Unknown/rarely classified due to unique form
• Geological Stage: Bajocian (~170 million years ago)
• Depositional Environment: Shallow carbonate marine shelf
• Cenoceras inornatum: A smooth-shelled Jurassic nautiloid with a classic involute coiled form and a central siphuncle. It was likely a slow-moving predator or scavenger.
• Order: Nautilida
• Family: Nautilidae
• Geological Stage: Bajocian (Middle Jurassic)
• Depositional Environment: Shallow, warm marine waters of the oolitic platform

This fossil has been expertly cleaned, prepped, and treated by Alison, and its superb preservation highlights the distinct features of both species. The photo shows the exact specimen you will receive, and includes a 1cm scale cube for accurate sizing—please refer to the image for full details.

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity (COA), confirming their identity and provenance.

This is an extremely rare pairing, ideal for advanced collectors, museums, educational institutions, or anyone with an interest in unique and scientifically significant fossil specimens.

Origin: Burton Bradstock, Dorset, United Kingdom

Formation: Inferior Oolite

Age: Bajocian Stage, Middle Jurassic (~170 Ma)

Species: Spiroceras bifurcati & Cenoceras inornatum

Discovered by: Alister and Alison (30 April 2025)

Prepared by: Alison

Authenticity: 100% Genuine Fossil with COA