Harpoceras aalense Ammonite Fossil from Jurassic Aalenian Stage France Authentic Collectors Piece

Description

Geological Context

This Harpoceras aalense ammonite fossil comes from the Aalenian Stage of the Middle Jurassic, dating back around 174 to 170 million years ago. The Aalenian is the earliest stage of the Middle Jurassic and is named after the town of Aalen in Germany, though the species and related deposits are also widely recognised in France. This period represents a significant phase in Earth’s history, with fluctuating sea levels and shallow marine environments that supported a rich diversity of ammonites and other marine life.

Taxonomy and Classification

• Kingdom: Animalia
• Phylum: Mollusca
• Class: Cephalopoda
• Order: Ammonitida
• Superfamily: Hildoceratoidea
• Family: Hildoceratidae
• Genus: Harpoceras
• Species: Harpoceras aalense

The Harpoceras group is particularly noted for its significance in Jurassic biostratigraphy. Species like Harpoceras aalense are important index fossils, helping to define the Aalenian biozones and allowing geologists to correlate sedimentary sequences across Europe.

Morphological Features

This fossil exhibits several features that make Harpoceras aalense easily recognisable and highly prized:

• Strongly ribbed shell with pronounced lateral ribs that extend across the flanks.
• Planispiral coiling, meaning the whorls lie in a single plane, forming a flat spiral.
• Compressed whorl section, giving the shell a flattened appearance compared to other Jurassic ammonites.
• Deep ventral groove, a hallmark of the genus Harpoceras.
• Intricate suture patterns, visible in well-preserved specimens, highlighting the complexity of ammonite shell structure.

These traits not only aid in precise identification but also make the specimen visually striking and scientifically valuable.

Depositional Environment

The fossil originates from marine sediments laid down in shallow seas that once covered large areas of present-day France. The environment was dominated by fine-grained clays and marls, ideal for fossil preservation. Such conditions allowed ammonites like Harpoceras aalense to be preserved in detail, retaining their diagnostic ribbing and shell structure.

Scientific and Collector Importance

• Biostratigraphic Value – Harpoceras aalense is an important index fossil of the Aalenian, used to define time intervals within the Jurassic.
• Evolutionary Significance – It represents a key point in the evolutionary lineage of the Hildoceratidae family.
• Collector’s Appeal – The ribbed morphology and clean lines make it a desirable display specimen.
• Educational Use – A superb teaching tool for illustrating Jurassic ammonite diversity and morphology.

Authenticity and Presentation

• Supplied with a Certificate of Authenticity.
• The specimen in the photo is the exact fossil you will receive, carefully selected for quality and preservation.
• A 1 cm scale cube is shown in the image for accurate sizing.

This Harpoceras aalense ammonite fossil from the Aalenian Stage of the Jurassic in France is a superb collector’s specimen. Its combination of geological significance, distinctive ribbing, and excellent provenance makes it an outstanding addition to any fossil collection or educational display.