Rare Vermisphinctes Ammonite Fossil, Upper Bajocian Stage Jurassic, Authentic Madagascar Collectors Piece with Certificate of Authenticity

Description

Authentic Jurassic Ammonite Fossil

This listing offers a genuine Vermisphinctes Ammonite Fossil from the Upper Bajocian Stage of the Middle Jurassic, discovered in Madagascar. Ammonites are extinct marine molluscs belonging to the subclass Ammonoidea, relatives of modern squid and cuttlefish. Their chambered, coiled shells made them efficient swimmers in Jurassic seas and have left behind some of the most striking and scientifically important fossils known today. The photographs show the exact specimen available, with a 1 cm scale cube included for accurate measurement.

Geological Context – Upper Bajocian, Jurassic

The Bajocian Stage, dated to about 170–168 million years ago, represents an interval of the Middle Jurassic when ammonites diversified widely, producing a great variety of shell forms. The Upper Bajocian is especially important for biostratigraphy, as many ammonite species evolved rapidly and serve as excellent index fossils for correlating rock layers across different regions.

In Madagascar, during the Jurassic, much of the island was submerged beneath shallow tropical seas connected to the Tethys Ocean. These conditions supported thriving ecosystems rich in ammonites, belemnites, bivalves, and marine reptiles. The warm waters and fine sediment deposition allowed the exceptional preservation of ammonite shells such as Vermisphinctes.

Species Profile – Vermisphinctes

The genus Vermisphinctes belongs to the family Perisphinctidae, within the superfamily Perisphinctoidea and order Ammonitida. This group is well known for its evolute shells and complex ribbing, which make them distinctive among Bajocian ammonites.

Key characteristics of Vermisphinctes ammonites include:

• Strongly evolute shell, with inner whorls clearly visible.
• Prominent ribbing, often bifurcating or branching as it crosses the flanks.
• A wide umbilicus exposing much of the earlier growth stages.
• Rounded to subangular venter, with ribs extending uninterrupted across it.
• Distinctive suture lines marking the chamber separations inside the shell.

These traits give Vermisphinctes fossils their striking appearance and scientific importance. They represent a key ammonite lineage of the Bajocian, useful in defining biozones and understanding evolutionary trends within the Perisphinctidae.

Paleoenvironment and Scientific Importance

In the Upper Bajocian seas of Madagascar, ammonites like Vermisphinctes thrived as nektonic predators. Their buoyant, chambered shells allowed them to move efficiently through the water while hunting small crustaceans and other invertebrates. When they died, their shells sank to the seabed, where rapid burial in fine sediment preserved them for millions of years.

The presence of Vermisphinctes in Jurassic deposits is crucial for paleontologists, as the genus provides important data for biostratigraphy and helps refine the geological timescale of the Middle Jurassic. Their distinctive morphology makes them reliable indicators for correlating Bajocian strata across regions as far apart as Europe and Gondwana.

100% Genuine with Certificate of Authenticity

Every specimen we sell is 100% genuine and comes with a Certificate of Authenticity. This guarantees that your ammonite fossil is an authentic relic of Jurassic seas and not a cast or reproduction.

A Collector’s and Display Fossil

This Vermisphinctes ammonite fossil from the Upper Bajocian of Madagascar is an exceptional specimen, combining scientific significance with visual appeal. Its pronounced ribbing, clear evolutionary features, and provenance from a classic Jurassic locality make it a valuable piece for collectors, educators, and natural history enthusiasts alike.

Scale Rule Squares / Cube = 1 cm. Please see listing photos for the full sizing of this exact specimen.