Description
Genuine Juvenile Brodieia curva Ammonite Fossil
This carefully selected specimen is a genuine juvenile Brodieia curva ammonite from the Upper Toarcian of Dorset, England, UK. It represents an extinct marine cephalopod that inhabited the Jurassic seas covering southern Britain during the later part of the Early Jurassic.
Juvenile ammonites are particularly interesting because they preserve an early stage in the animal’s shell development. The compact proportions and developing ornamentation provide a fascinating contrast with the larger, more mature shells ordinarily associated with ammonite displays. Each fossil is naturally individual, with its own preservation, colour, matrix and surface characteristics formed through millions of years of geological change.
The listing photographs show the actual fossil specimen you will receive. Full sizing and scale information can be seen in the accompanying photograph.
Fossil Classification and Geological Information
Scientific name: Brodieia curva
Fossil type: Juvenile ammonite
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Family: Phymatoceratidae
Geological period: Jurassic
Epoch: Early Jurassic
Stage: Toarcian
Stratigraphic position: Upper Toarcian
Locality: Dorset, England, UK
Brodieia is a genus of Toarcian ammonites associated with the phymatoceratid group. These ammonites formed part of the diverse cephalopod communities that flourished in European marine environments during the Early Jurassic. Some palaeontological interpretations regard Brodieia as representing the smaller microconch form associated with larger ammonites of the genus Haugia.
Microconchs are comparatively small adult forms found in ammonite groups that displayed shell dimorphism. However, this particular fossil is identified as a juvenile specimen, meaning that its smaller dimensions represent an early growth stage rather than necessarily indicating its eventual adult form.
Juvenile Ammonite Morphology
The shell of an ammonite grew continuously around a coiled, planispiral axis. As the animal increased in size, it added new shell material around the aperture, creating a succession of progressively larger whorls. Consequently, the inner part of every mature ammonite preserves the shell’s juvenile growth stages.
Juvenile examples such as this specimen allow the early development of the whorls, umbilicus and ribbing to be observed directly. Brodieia ammonites are generally characterised by coiled shells with a moderately open umbilical area, defined flanks and ribbing that extends towards the outer or ventral edge. The ribs may appear slightly curved or inclined, with their strength and spacing changing as the shell grows.
The original living chamber and internal chambered portion formed a lightweight but strong external shell. The animal occupied the final chamber, while the older chambers were separated by walls called septa. A narrow connecting tube known as the siphuncle helped regulate fluid and gas within these chambers, allowing the ammonite to control its buoyancy in the water.
Upper Toarcian Jurassic Age
The Toarcian is the final stage of the Early Jurassic Epoch and occurred approximately 184 to 174 million years ago. This specimen comes from the Upper Toarcian, placing it within the later portion of that stage and making it around 175 million years old.
Ammonites are among the most valuable index fossils used in Jurassic geology. Their rapid evolutionary changes, abundant fossil record and broad geographical distribution allow palaeontologists to divide sedimentary sequences into detailed ammonite zones and subzones. Different shell forms appearing successively through the rock record enable strata from separate locations to be compared and correlated.
A fossil such as this juvenile Brodieia curva therefore has value beyond its attractive coiled shape. It represents evidence of both biological development and a precisely recognisable interval within Early Jurassic geological history.
Jurassic Marine Environment of Dorset
During the Toarcian, Dorset was situated beneath a warm sea at a considerably lower latitude than it occupies today. Southern Britain formed part of an extensive marine region connected to the developing Atlantic and the broader Tethyan oceanic system.
Fine mud, silt, carbonate material and organic debris accumulated across the seabed. Ammonites lived within the water column alongside belemnites, fish, marine reptiles, bivalves, brachiopods and other invertebrates. After an ammonite died, its shell could descend to the seabed and become covered by sediment.
Continued burial compacted the sediment and transformed it into rock. Mineral-rich groundwater entered the shell or its surrounding cavity, creating an internal mould or replacing portions of the original shell material. Later erosion exposed these fossil-bearing Jurassic deposits along the Dorset coast and within inland rock formations.
Dorset forms part of one of Britain’s most celebrated fossil regions. Its internationally important Jurassic rocks preserve a remarkably detailed record of changing marine environments and the animals that occupied them.
Actual Fossil Specimen
This is a carefully chosen, genuine fossil rather than a replica, cast or reproduction. Natural variations in colour, texture, matrix, completeness and surface preservation are authentic features of the specimen and reflect its long geological history.
The photograph shows the exact Brodieia curva juvenile ammonite that will be supplied, so you can examine its individual shape and preservation before purchasing. Full sizing is provided in the photograph.
The fossil includes a generic Certificate of Authenticity card with a lifetime guarantee of authenticity. It is an excellent addition to a British fossil collection, ammonite display, Jurassic educational collection or natural-history cabinet and would also make a distinctive gift for a fossil collector, geology enthusiast or admirer of the Jurassic Coast.
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