Description
Genuine Esericeras esericeri Ammonite Fossil
This genuine ammonite fossil is identified as Esericeras esericeri and originates from France. It dates from the Toarcian Stage of the Lower Jurassic and preserves the remains of an extinct marine cephalopod that lived in the ancient seas of Europe approximately 174–184 million years ago.
The specimen combines a recorded species identification with a defined geological stage, giving it valuable palaeontological, educational and collecting interest. It provides a tangible connection to an important interval of Jurassic history, when ammonites were among the most abundant and rapidly evolving animals within marine ecosystems.
This carefully chosen fossil is the exact specimen shown in the listing photographs. Its natural shell profile, surface detail, mineral colouring, surrounding matrix and individual state of preservation can therefore be examined before purchase. Full sizing and scale information are provided in the photographs.
Esericeras esericeri Identification
Esericeras esericeri belongs to the ammonites, an extinct group of externally shelled marine molluscs that flourished throughout much of the Mesozoic Era. Ammonites were cephalopods and were therefore related to living squid, cuttlefish, octopuses and nautiluses.
Its broad scientific classification includes:
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Genus: Esericeras
Species: Esericeras esericeri
Ammonite identification is based on a combination of shell features, including coiling style, whorl proportions, umbilical width, ribbing, ventral structure and internal suture patterns. These characteristics may change as the animal grows, meaning that juvenile and mature portions of the same shell can display noticeable differences.
The amount of diagnostic detail visible on a fossil also depends on its preservation. Some specimens retain areas of original or mineral-replaced shell, while others are preserved mainly as natural internal moulds formed by sediment that entered the empty shell chambers.
Jurassic Ammonite Shell Morphology
The shell of Esericeras esericeri developed as a planispiral coil, with successive whorls growing around one another within approximately the same plane. The earlier whorls form the central part of the fossil, while the later and larger whorls record the ammonite’s continued growth.
The central opening is known as the umbilicus. Its width, together with the degree to which later whorls overlap earlier ones, is an important feature in ammonite classification. Shells in which earlier whorls remain widely visible are described as evolute, while tightly overlapping forms are known as involute.
The surface may preserve ribs, folds or fine growth lines extending across the flanks. Rib strength, spacing and curvature could vary during development and may appear differently depending on whether the fossil preserves the original exterior or an internal sedimentary mould.
The outer edge of the shell is called the venter. Its shape may be rounded, flattened or more narrowly defined, and it can provide additional evidence when comparing related ammonites. Natural wear or incomplete preservation may soften or obscure these original features.
Chambered Shell and Buoyancy System
Internally, the ammonite shell was divided by curved partitions called septa. These formed a sequence of chambers linked by a narrow tube known as the siphuncle.
The living animal occupied only the final and largest body chamber. As it increased in size, it added new shell material around the aperture, moved forwards and sealed the older portion behind itself with another septum.
The abandoned chambers functioned as part of the ammonite’s buoyancy system. By adjusting the balance of liquid and gas within them, the animal could control its position in the water column.
Where the septa joined the outer shell wall, they created intricate patterns called suture lines. These structures are among the most important features used by palaeontologists to classify ammonites and study their evolutionary relationships.
The soft-bodied animal would have extended its head, eyes and muscular arms from the shell opening. It probably fed upon small marine organisms, planktonic animals and organic material encountered within the surrounding sea.
Toarcian Lower Jurassic Age
This fossil dates from the Toarcian, the final stage of the Lower Jurassic. The Toarcian followed the Pliensbachian and preceded the Aalenian, which marks the beginning of the Middle Jurassic.
The Toarcian was an interval of major environmental and biological change. Marine conditions shifted considerably, while ammonite faunas underwent repeated episodes of diversification, migration and extinction. These changes created a detailed succession of species that can be recognised within sedimentary rocks.
Ammonites are especially valuable index fossils because many species evolved rapidly and existed for comparatively limited spans of geological time. Their broad distribution across connected seas allows geologists to compare and correlate rock layers exposed in different countries.
The documented Toarcian age therefore gives this Esericeras esericeri specimen considerably more scientific context than an ammonite described only as generally Jurassic.
Early Jurassic Marine Environment of France
During the Toarcian, large areas of what is now France were covered by warm seas connected to the western Tethys Ocean. These marine environments included shallow shelves, carbonate platforms and deeper sedimentary basins.
The waters supported ammonites, belemnites, nautiloids, bivalves, gastropods, brachiopods, crustaceans, fish and marine reptiles. Microscopic plankton formed a major part of the marine food web and contributed organic and calcareous material to the sediments accumulating below.
Fine mud, clay, carbonate particles and shell debris settled onto the seabed. Changes in sea level, water circulation, oxygen availability, biological productivity and sediment supply produced alternating layers of limestone, marl and clay.
The ammonite represented by this specimen lived within the water column above that seabed. Its chambered shell provided protection and buoyancy while the animal moved through a diverse Jurassic marine ecosystem.
Natural Fossilisation and Preservation
After the ammonite died, its shell descended to the seabed. Currents, scavenging organisms and sediment movement may have affected it before final burial.
Fine sediment entered the empty chambers and accumulated around the exterior. As additional deposits built up, pressure compacted the surrounding material and gradually transformed it into sedimentary rock.
The original shell was composed mainly of aragonite, a form of calcium carbonate that can dissolve, recrystallise or be replaced by other minerals during fossilisation. Sediment filling the chambers could harden into a natural internal mould that retained the ammonite’s coiled form and parts of its ornamentation.
Natural fractures, incomplete edges, worn shell areas, matrix deposits, mineral markings and variations in colour are authentic products of burial and geological alteration. These characteristics form part of the fossil’s history and make every specimen individually unique.
Actual Specimen and Certificate of Authenticity
This is a genuine fossil specimen and not a cast, replica or artificial reproduction. The listing photographs show the exact Esericeras esericeri ammonite that will be supplied, allowing its natural shell form, preservation, matrix, mineral colouring and individual surface characteristics to be viewed before purchase.
Full sizing is shown in the listing photographs.
The fossil includes a generic Certificate of Authenticity card carrying a lifetime guarantee. Its recorded species identification, Toarcian age and French provenance make it an excellent addition to a Jurassic ammonite collection, European fossil display, natural-history cabinet or educational geological collection.
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