Description
Genuine Collina cf. pseudoyoungi Ammonite Fossil
This genuine Collina cf. pseudoyoungi ammonite fossil was collected from Saint-Paul-des-Fonts in Aveyron, Occitanie, southern France. Dating from the Middle Toarcian Stage of the Lower Jurassic Period, it represents an extinct marine cephalopod that inhabited the ancient seas of Europe approximately 180 million years ago.
The abbreviation “cf.”, meaning “compare with”, indicates that the specimen closely resembles the diagnostic form of Collina pseudoyoungi but has been conservatively identified because not every feature required for an unequivocal species-level determination may be visible. This careful identification preserves the scientific value of the fossil without overstating its classification.
The specimen has been individually chosen for its natural character, fossil detail and geological interest. The photographs show the actual fossil you will receive, rather than a stock or representative image. Please examine the photographs for the specimen’s full sizing, scale, preservation, colour, matrix and visible ornamentation.
Middle Toarcian Fossil from Aveyron
The Toarcian is the final stage of the Lower Jurassic Epoch, following the Pliensbachian and preceding the Aalenian. It was a significant interval in ammonite evolution, during which numerous distinctive groups developed and spread through marine environments across Europe and the western Tethyan region.
Collina pseudoyoungi was formally established by Swiss palaeontologist Jean Guex in 1972 during his study and revision of Middle Toarcian ammonites from the southern margin of the Causses in France. The type locality is Saint-Paul-des-Fonts, making material attributed to this species from the same area especially interesting to collectors of carefully localised Jurassic ammonites.
The species is associated with Middle Toarcian marine deposits and has been recorded from strata belonging to the Bifrons Zone. Ammonite biozones are divisions of geological strata recognised through characteristic ammonite assemblages. Because ammonites evolved rapidly and were widely distributed, they are particularly useful as index fossils for dating and correlating Jurassic sedimentary rocks.
Distinctive Collina Shell Morphology
Collina ammonites possessed planispirally coiled shells divided internally into a succession of chambers. The living animal occupied the final and largest body chamber, while the older sealed chambers formed the phragmocone. A narrow structure called the siphuncle connected these chambers and helped the ammonite regulate its buoyancy in the water.
Members of the genus generally display an evolute shell form, leaving earlier whorls visible around a comparatively open central umbilicus. The whorl section may be angular or quadrate, while the shell flanks carry strong, widely spaced ribs.
The primary ribs can divide into two or three secondary ribs near prominent ventrolateral tubercles. These secondary ribs commonly curve or project forwards as they cross towards the venter, creating a strongly sculptured appearance. Rib spacing, tuberculation and whorl proportions may change during growth, so the inner and outer portions of a specimen can display different ornamental characteristics.
These robust ribs and raised nodes strengthened the shell and now provide palaeontologists with important features for distinguishing Collina from related Toarcian ammonites.
Scientific Classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Eoderoceratoidea
Family: Dactylioceratidae
Genus: Collina
Comparison species: Collina pseudoyoungi Guex, 1972
Ammonites were marine molluscs related to living cephalopods such as squid, cuttlefish, octopuses and nautiluses. They became exceptionally diverse throughout the Jurassic and Cretaceous periods before disappearing during the end-Cretaceous extinction event.
Jurassic Marine Environment of Saint-Paul-des-Fonts
During the Middle Toarcian, the area now forming Aveyron lay beneath a marine environment connected with the western Tethys. Fine mud, carbonate material and the remains of marine organisms accumulated on the seabed, creating fossil-bearing sedimentary deposits.
After the ammonite died, its shell settled onto the sea floor. Burial beneath soft sediment protected parts of it from currents, scavengers and complete dissolution. Continued sediment accumulation gradually compacted the layers into rock, while mineral-rich groundwater filled voids and preserved or replaced parts of the original shell.
Any attached matrix, mineral deposits, fine fractures, worn areas or incomplete shell sections are natural products of this lengthy process. Such features are expected in authentic fossils and form part of the specimen’s individual geological history.
Saint-Paul-des-Fonts is an important locality in the southern Causses region and has contributed significant material to the scientific study of Middle Toarcian ammonites. A specimen with this recorded locality offers valuable context for geological, palaeontological and comparative collections.
Actual Specimen with Certificate of Authenticity
This is a 100% genuine fossil specimen, not a replica, cast or modern reproduction. It is supplied with a generic Certificate of Authenticity card carrying a lifetime guarantee, providing lasting reassurance regarding its genuine fossil status.
The exact Collina cf. pseudoyoungi ammonite shown in the listing photographs will be supplied. Its natural colour, preservation, visible ribbing, matrix and surface characteristics will therefore match the fossil pictured.
This specimen is suitable for ammonite collections, Lower Jurassic displays, geological reference cabinets, natural-history collections, educational use and gifts for fossil enthusiasts. Its Middle Toarcian age, conservative scientific identification and documented Saint-Paul-des-Fonts origin make it an appealing addition to a collection of authentic French Jurassic fossils.
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