Sigaloceras calloviense Ammonite Fossil from Kellaways Beds Jurassic Callovian Latton Quarry Cotswold Water Park Swindon UK

Description

Geological Context and Provenance

This specimen is an authentic Sigaloceras calloviense ammonite fossil from the Kellaways Beds of the Callovian Stage, Middle Jurassic (approximately 166 – 163 million years ago). It was unearthed at Latton Quarry, Cotswold Water Park, Swindon, UK, a site well-known for yielding beautifully preserved ammonites and other marine fossils. The Kellaways Beds form part of the Great Oolite Group, a sequence of marine sediments deposited in shallow seas that once covered much of southern England.

The Callovian is a critical stage for Jurassic stratigraphy, marked by abundant ammonite faunas that enable precise biostratigraphic dating. Sigaloceras calloviense is the index fossil for the Calloviense Zone, giving this specimen particular scientific importance.

Fossil Type and Species Information

The genus Sigaloceras belongs to the Order Ammonitida, Superfamily Stephanoceratoidea, and Family Tulitidae. The species Sigaloceras calloviense is especially significant as it defines the lower Callovian stratigraphy. Its distinct morphology and widespread distribution make it a cornerstone species for palaeontological studies of the Middle Jurassic.

Morphological Features

This fossil shows the characteristic features of Sigaloceras calloviense:

• Planispiral Coiling – A tightly coiled shell with whorls partially embracing earlier ones.
• Strong Ribbing – The ribs extend across the flanks to the venter, giving the shell a strikingly ornate appearance.
• Distinct Keel – A sharp keel runs along the venter, a common trait in Callovian ammonites.
• Index Fossil Characteristics – Its morphology is so distinctive that it has long been used as a primary fossil marker for Callovian strata.

These features not only give the ammonite its scientific value but also contribute to its aesthetic appeal as a display fossil.

Depositional Environment

The Kellaways Beds consist of sandy clays and fine-grained sediments deposited in a shallow marine shelf environment. These calm seas supported diverse marine life, with ammonites, bivalves, and marine reptiles thriving in abundance. The rapid burial of organisms in soft sediments contributed to their exceptional preservation, allowing fine details of ammonite shells to survive for millions of years.

Scientific and Collector Significance

Owning a Sigaloceras calloviense ammonite is both scientifically and historically important:

• Stratigraphic Value – As an index fossil, it defines the Calloviense Zone of the Callovian Stage.
• Collector’s Appeal – Its detailed ribbing and classic ammonite form make it a standout specimen.
• Provenance – Fossils from Latton Quarry are highly regarded due to their preservation quality and their role in British Jurassic geology.

Authenticity and Presentation

• 100% Genuine Specimen – Supplied with a Certificate of Authenticity.
• Exact Fossil You Receive – The photos show the actual ammonite offered for sale.
• Scale Reference – Scale rule squares / cube = 1 cm; see photos for full measurements.

This Sigaloceras calloviense ammonite fossil from the Jurassic Kellaways Beds of Swindon represents a perfect combination of scientific importance and collector appeal, offering both geological history and natural beauty in one specimen.