RARE 8″ Sonninia micracanthica Fossil Ammonite – Inferior Oolite, Middle Bajocian, Jurassic – Oborne Wood UK – Alice Purnell Collection

Description

A stunning and scientifically notable 8-inch specimen of Sonninia micracanthica, a beautifully preserved fossil ammonite from the Inferior Oolite Formation of the Middle Bajocian Stage, Jurassic Period. Collected at Oborne Wood, United Kingdom, this impressive ammonite is part of the well-documented Alice Purnell Collection. The exact specimen shown in the photograph is the one you will receive.

Geological Context:

• Species: Sonninia micracanthica
• Geological Period: Jurassic
• Stage: Middle Bajocian (~170 to 168 million years ago)
• Formation: Inferior Oolite
• Location: Oborne Wood, United Kingdom
• Depositional Environment: Shallow marine shelf with well-oxygenated, carbonate-rich oolitic sediments. These were laid down in a stable, warm sea supporting abundant ammonite faunas during a Jurassic marine transgression.

Taxonomic Classification:

• Family: Sonniniidae
• Superfamily: Hildoceratoidea
• Order: Ammonitida
• Suborder: Ammonitina
• Formally Described By: Buckman (1910s)

Morphological Features:

Sonninia micracanthica is characterised by a moderately evolute shell, pronounced ribbing, and the presence of small, regularly spaced tubercles (spines) along the flanks. The whorls are compressed with strong ornamentation, and the venter is typically rounded to weakly keeled. These small spines (reflected in the name “micracanthica”) add a distinctive texture, making it a desirable specimen both visually and scientifically.

The example here exhibits excellent preservation of those diagnostic features, with clean ribbing and intact tuberculation across the shell.

Stratigraphic and Scientific Importance:

Sonninia micracanthica occurs within the Middle Bajocian ammonite biozones, contributing to precise stratigraphic correlation within the Inferior Oolite of southern England. Its distinct morphology and regional endemism make it an important species for interpreting palaeoecological shifts and evolutionary trends among Sonniniidae during the mid-Jurassic.

Additional Details:

• All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.
• Scale Rule Squares / Cube = 1cm. Please refer to the listing photo for full dimensions and condition.
• This fossil is part of the highly regarded Alice Purnell Collection, known for scientifically authenticated and carefully prepared specimens.

This Sonninia micracanthica ammonite is a striking fossil that embodies the diversity of the Jurassic seas of Britain. A valuable addition to any collector’s or educator’s display, with both visual appeal and scientific significance.

Secure this rare 8-inch ammonite from the Jurassic today.