Promicroceras marstonense Ammonite Fossils Marston Marble Jurassic UK Genuine Specimen Certificate

Description

Genuine Jurassic Fossils – Promicroceras marstonense Ammonites

This listing is for a beautiful cluster of Promicroceras marstonense Fossil Ammonites, preserved within the famous Marston Marble from Marston Magna, Somerset, United Kingdom. These ammonites date back to the Lower Lias, Lower Jurassic, specifically the Obtusum Zone, around 195 million years old. Fossils from this location are rare and highly desirable, with multiple ammonites preserved together in decorative limestone slabs. Each specimen is photographed individually, ensuring that you receive the exact fossil shown. A Certificate of Authenticity is included with every purchase.

Geological Age and Provenance

These ammonites come from the Lower Jurassic Period, specifically the Lower Lias, within the Obtusum Zone. The deposits at Marston Magna are world-renowned for their richly fossiliferous limestone, historically called Marston Marble. This decorative stone has been used since the 18th century in architectural features, prized for its striking appearance filled with beautifully preserved ammonites. The fossils formed in a shallow marine environment, where fine silts and limestones buried ammonites soon after death, creating remarkable natural displays that remain stunning even after nearly 200 million years.

Fossil Type and Classification

This specimen showcases Promicroceras marstonense, a small but distinctive ammonite species within the family Eoderoceratidae, superfamily Eoderoceratoidea, and order Ammonitida. Ammonites were extinct cephalopods related to squids and cuttlefish, with chambered shells used for buoyancy. Promicroceras marstonense is an important ammonite species of the Lower Jurassic and has become closely associated with the Marston Marble beds that bear its name.

Morphology and Distinctive Features

The ammonites of Promicroceras marstonense are easily recognised by:

• Their small, compact planispiral shells, tightly coiled in elegant spirals.
• Fine, evenly spaced ribbing, which continues across the venter.
• A relatively narrow umbilicus, allowing inner coils to be clearly visible.
• Delicate but distinctive symmetry that makes them highly aesthetic when seen in groups.

In this specimen, multiple ammonites are preserved together in the limestone, creating a striking natural display. The fossil slab is as scientifically valuable as it is visually beautiful.

Biozone and Scientific Importance

Promicroceras marstonense is one of the defining ammonites of the Obtusum Zone, making it a crucial index fossil in Lower Jurassic stratigraphy. Its widespread distribution and distinctive morphology allow geologists to identify and correlate rocks from this time period across Europe. This makes it not only a desirable collector’s specimen but also an important piece of paleontological evidence used in understanding Earth’s geological past.

Depositional Environment

During the Early Jurassic, the area around Marston Magna was covered by a shallow sea. Fine sediments and carbonate muds accumulated, forming limestone rich in marine life. Ammonites such as Promicroceras marstonense thrived in these seas as active predators. After death, their shells settled on the seafloor, where rapid burial by lime mud preserved them in dense concentrations. Over millions of years, these became the ammonite-rich limestone layers known as Marston Marble, prized for their natural beauty.

Historical and Collecting Value

Marston Marble fossils have long been admired, both for their scientific importance and for their decorative appeal. In the 18th and 19th centuries, slabs of Marston Marble were polished and used in churches, houses, and ornamental displays. Today, specimens featuring multiple Promicroceras marstonense ammonites remain highly collectible due to their rarity and distinctive character. Owning such a piece connects you to both Britain’s fossil heritage and its cultural history.

Authenticity and Presentation

• 100% Genuine Fossil Specimen
• Species: Promicroceras marstonense
• Age: Jurassic, Lower Lias, approx. 195 million years old
• Zone: Obtusum Zone
• Location: Marston Magna, Somerset, United Kingdom
• Supplied with a Certificate of Authenticity
• Scale cube in photographs = 1 cm for accurate sizing
• The specimen pictured is the exact fossil you will receive

This rare Promicroceras marstonense ammonite fossil slab from the famous Marston Marble is a superb collector’s piece, combining geological importance, historical value, and natural beauty in one exceptional specimen.