Description
Grade A Perisphinctes Ammonite – Lower Jurassic Fossil from Tulear, Madagascar
This exceptional Grade A Perisphinctes ammonite fossil originates from the world-famous Lower Jurassic deposits near Tulear (Toliara), Madagascar. With outstanding rib detail, clean whorl definition, and beautiful natural mineralisation, this specimen represents one of the most iconic ammonites of the Early Jurassic seas. The fossil shown in the photographs is the exact specimen you will receive, illustrated with 1 cm scale cubes for accurate sizing. All of our Fossils are 100% Genuine Specimens and come with a Certificate of Authenticity.
Geological Age and Formation
This ammonite comes from the Lower Jurassic, specifically the Late Toarcian to Early Aalenian interval, a period occurring roughly 180–174 million years ago. The Tulear region of Madagascar is globally known for producing remarkably preserved ammonites due to its stable, fine-grained marine sedimentation.
The ammonites lived in warm, shallow tropical seas that surrounded the early breakup of Gondwana. After death, their shells settled into soft seabed sediments where mineral-rich waters permeated them, often replacing original aragonite with calcite or forming natural agate infill that enhances the fossil’s preservation and display quality.
Fossil Type, Species, and Classification
Fossil Type
- Ammonite (Subclass Ammonoidea) – extinct cephalopods related to squid and cuttlefish.
Species and Taxonomy
Most ammonites of this form from Madagascar belong to the genus Perisphinctes, known for its elegantly ribbed shell and widespread distribution.
- Order: Ammonitida
- Superfamily: Perisphinctoidea
- Family: Perisphinctidae
- Genus: Perisphinctes
- Species: Commonly part of the Perisphinctes group characteristic of Lower and Middle Jurassic strata
These ammonites are widely used as important biozone markers, aiding geologists in correlating Jurassic marine sediments across continents.
Morphological Features
This specimen displays all the hallmark traits of a high-quality Perisphinctes ammonite, including:
- Strong, sharp ribbing radiating uniformly from the umbilicus to the venter
- Planispiral coiling with clearly exposed earlier whorls
- Well-defined umbilicus characteristic of the genus
- Ribs sometimes bifurcating, forming elegant branching patterns across the whorls
- Rounded to slightly compressed venter depending on species group
- Fine suture lines that may be visible where preservation is particularly detailed
- Glossy natural mineralisation typical of Madagascan ammonites polished through geologic processes
The clarity of ornamentation on this Grade A specimen makes it an ideal reference example for collectors and enthusiasts.
Depositional Environment
Jurassic Madagascar was part of a shallow, tropical marine system with rich biodiversity. The sea floor accumulated layers of fine silt and carbonate muds. In these oxygen-poor environments, ammonite shells often fossilised rapidly, preserving exceptional ribbing and suture detail.
The steady sedimentation and mineral-rich waters present in the region helped produce the famous Madagascan ammonites known for their stability, colour, and aesthetic appeal.
Scientific and Collector Significance
Perisphinctes ammonites are valuable for their:
- Use in stratigraphic correlation across the Jurassic
- Diagnostic rib patterns and suture structures
- Abundance in major fossil beds aiding evolutionary studies
- Beautiful display quality, appreciated by collectors worldwide
Their consistent morphology and wide distribution make them one of the most recognisable ammonite groups in paleontology.
Grade A Quality and Display Appeal
This specimen has been selected for its:
- Exceptionally clear ribbing with little weathering
- Strong symmetry and well-preserved whorl exposure
- Natural mineral enhancement characteristic of Tulear fossils
- Attractive shape suitable for both display and study
- Solid, stable structure ideal for long-term collection care
The fossil is both scientifically informative and visually captivating, making it an outstanding centrepiece for any natural history collection.
Ideal for Collectors, Fossil Enthusiasts, and Display Settings
This Grade A Perisphinctes ammonite from Tulear offers an outstanding blend of geological heritage, natural beauty, and paleontological significance. With its detailed ornamentation, strong preservation, and iconic Jurassic provenance, it is a remarkable specimen for collectors, educators, and fossil enthusiasts alike.
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