Perisphinctes spirorbis Ammonite Fossil from Jurassic Callovian Kellaways Beds Latton Quarry Cotswold Water Park Swindon UK

Description

Geological Context and Provenance

This is a genuine Perisphinctes spirorbis ammonite fossil from the Kellaways Beds, Callovian Stage of the Middle Jurassic (approximately 166–163 million years ago). It was discovered at Latton Quarry, within the Cotswold Water Park, Swindon, UK, an internationally recognised locality for Jurassic fossils. The Kellaways Beds represent shallow marine shelf deposits of sandy clays and silts laid down in a warm epicontinental sea that covered much of present-day southern England during the Jurassic.

Ammonites from the Callovian are highly important stratigraphically, and Perisphinctes spirorbis is a well-documented species used by geologists to refine biozones and correlate sedimentary layers across Europe.

Fossil Type and Species Information

The genus Perisphinctes belongs to the Order Ammonitida, Superfamily Perisphinctoidea, and Family Perisphinctidae. Ammonites of this genus are renowned for their regularly ribbed, evolute shells and their role as vital biostratigraphic markers. The specific species, Perisphinctes spirorbis, is particularly noted for its distinctive ribbing pattern and its stratigraphic position within the Callovian sequence.

Morphological Features

This specimen displays the typical features of Perisphinctes spirorbis:

• Evolute coiling – with all whorls clearly visible, exposing much of the earlier shell growth.
• Prominent ribbing – strong, radial ribs that cross the flanks of the shell, a key feature of this genus.
• Rounded whorl section – creating a balanced, symmetrical form.
• Well-defined sutures – showing the complex suture line patterns typical of Callovian ammonites.

These morphological features not only add aesthetic appeal but also highlight its scientific significance as an identifiable Callovian ammonite.

Depositional Environment

The Kellaways Beds were deposited in shallow marine conditions influenced by fluctuating sea levels and periodic influxes of fine sand and silt. Such environments were ideal habitats for ammonites, belemnites, and bivalves, as well as marine reptiles. Fossil preservation in these sediments is often excellent, with ammonites retaining intricate ribbing and suture detail, as demonstrated by this specimen.

Scientific and Collector Significance

• Stratigraphic Value – Perisphinctes spirorbis is a marker species used to define Callovian ammonite biozones.
• Collector’s Interest – Its well-preserved ribbing and classical ammonite form make it a highly desirable piece.
• Educational Use – Provides insight into Jurassic ammonite diversity and marine paleoecology.

Authenticity and Display

• 100% Genuine Fossil – Supplied with a Certificate of Authenticity.
• Exact Specimen – The photos provided show the actual ammonite you will receive.
• Scale Reference – Square rule/cube = 1 cm; see images for precise sizing.

This Perisphinctes spirorbis ammonite fossil from the Callovian Kellaways Beds of Latton Quarry, Swindon is both scientifically important and visually striking. With its strong ribbing, excellent preservation, and clear provenance, it is a perfect addition for collectors, educators, or enthusiasts of Jurassic paleontology.