Description
Genuine Garantiana subgaranti Ammonite Fossil
This carefully selected fossil is an authentic specimen of Garantiana subgaranti, an ammonite dating from the Bajocian Stage of the Middle Jurassic Period. Discovered in Normandy, France, it represents a marine animal that lived in the warm seas covering parts of Europe approximately 168 to 170 million years ago.
The photograph shows the actual fossil specimen you will receive, allowing you to examine its natural preservation, shape, surface detail and individual character before purchasing. Full sizing and proportions can be seen in the accompanying photograph.
Your fossil includes a generic Certificate of Authenticity card with a lifetime guarantee, confirming that it is a genuine fossil specimen.
Fossil Species and Classification
Scientific name: Garantiana subgaranti
Fossil type: Ammonite
Order: Ammonitida
Superfamily: Stephanoceratoidea
Family: Stephanoceratidae
Geological period: Jurassic
Epoch: Middle Jurassic
Stage: Bajocian
Locality: Normandy, France
Garantiana is a recognised genus of evolute, strongly ornamented ammonites associated with Middle Jurassic marine deposits. The genus belongs to the Stephanoceratidae, a diverse family whose members are particularly useful to palaeontologists studying the age and correlation of Bajocian sedimentary rocks.
The species Garantiana subgaranti is associated with the later part of the Bajocian and is well known within European ammonite assemblages. Ammonites of this type are valued both for their decorative ribbing and for their importance in Jurassic biostratigraphy.
Ammonite Morphology and Natural Features
Ammonites were extinct marine cephalopods related to modern squid, cuttlefish, octopuses and nautiluses. They possessed coiled, chambered shells divided internally by walls known as septa. As the animal grew, it occupied the largest outer chamber while the abandoned inner chambers helped regulate buoyancy in the water column.
Garantiana ammonites typically display an evolute shell form, meaning that much of the earlier coiling remains visible rather than being completely covered by later whorls. Their ornamentation commonly consists of pronounced ribs that divide or branch as they extend across the whorl. Small tubercles or raised points may occur where the ribbing changes direction, giving the shell a strongly sculptured appearance.
The exact amount of visible ribbing, whorl structure, matrix and natural surface preservation varies between specimens. These differences are part of the fossil’s authenticity and ensure that every example is individually distinctive.
Bajocian Geology of Normandy
During the Bajocian Stage, the region now forming Normandy was influenced by shallow epicontinental seas connected to the wider Jurassic oceans of western Europe. Marine sediments accumulated on and around carbonate platforms, preserving ammonites alongside other organisms such as bivalves, brachiopods, belemnites, gastropods and marine invertebrates.
The Bajocian Stage was named after Bayeux in Normandy, making fossils from this region especially significant in the history of Jurassic geology. The stage forms an important interval within the Middle Jurassic and is divided into a detailed sequence of ammonite biozones. Rapid ammonite evolution, widespread marine distribution and readily recognisable shell features allow particular species and genera to be used for matching rock layers between different localities.
Normandy is therefore an internationally important source of Middle Jurassic fossils, offering specimens with both scientific relevance and strong historical connections to the development of geological classification.
Jurassic Marine Life and Fossil Formation
The living ammonite would have moved through the Jurassic sea using jet propulsion, drawing water into its body chamber and expelling it through a muscular funnel. Its chambered shell provided buoyancy control, while tentacles surrounding the mouth were likely used to capture small prey or gather food from the water.
After death, the shell settled onto the seabed and was buried by marine sediment. Over millions of years, compaction, mineralisation and chemical alteration transformed the surrounding deposit into rock. The original shell could be preserved, replaced by minerals or dissolved away, leaving an internal or external mould that retained the ammonite’s coiled shape and ornamentation.
Any natural fractures, incomplete areas, mineral deposits, matrix attachments or variations in colour are normal geological features produced during burial, fossilisation and later exposure.
Authentic Collectable Fossil Specimen
This Garantiana subgaranti ammonite is suitable for fossil collectors, Jurassic enthusiasts, geology students, educational displays and natural-history collections. Its identifiable species, Middle Jurassic age and Normandy provenance make it an appealing example of European ammonite palaeontology.
It also makes a distinctive natural display piece for an office, study, classroom, cabinet or home collection. Unlike a manufactured ornament, every fossil records a unique combination of ancient growth, preservation and geological history.
This is a carefully chosen genuine fossil, and the photographs show the exact specimen that will be supplied. Full sizing is shown in the photo. A Certificate of Authenticity lifetime guarantee generic card is included.
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