Paracymbytes obsoletus Ammonite Fossil Rare Sinemurian Jurassic Robin Hoods Bay Yorkshire UK

Description

Rare Paracymbytes obsoletus Ammonite Fossil from Robin Hoods Bay, Yorkshire

This listing offers a rare Paracymbytes obsoletus ammonite fossil from the Sinemurian stage of the Early Jurassic, discovered at the world-renowned Robin Hoods Bay, Yorkshire, United Kingdom. Dated to approximately 199–190 million years ago, this remarkable ammonite represents an important marine species preserved within the Lower Jurassic rocks of Britain. The photographs provided show the exact specimen you will receive, displayed alongside a 1 cm scale cube for accurate sizing.

All of our fossils are 100% genuine specimens and come with a Certificate of Authenticity, ensuring both scientific and collector value.

Geological Context – Sinemurian Stage, Early Jurassic

The Sinemurian stage is part of the Early Jurassic, a period following the Triassic-Jurassic extinction event, when ammonites diversified rapidly and became dominant marine organisms. Robin Hoods Bay, on the Yorkshire coast, is globally renowned for its exceptional Sinemurian ammonite faunas, preserved within the Whitby Mudstone and underlying strata.

The depositional environment at this locality consisted of shallow marine basins with fine sedimentation, ideal for the preservation of marine invertebrates. These conditions provided not only a rich fossil record of ammonites but also marine reptiles, bivalves, and gastropods, offering a window into life in the Early Jurassic seas.

Scientific Classification

• Genus: Paracymbytes
• Species: Paracymbytes obsoletus
• Family: Echioceratidae
• Superfamily: Eoderoceratoidea
• Order: Ammonitida
• Geological Stage: Sinemurian, Early Jurassic (199–190 million years ago)
• Locality: Robin Hoods Bay, Yorkshire, United Kingdom

Morphological Features of Paracymbytes obsoletus

The genus Paracymbytes is characterised by its elegant and diagnostic shell morphology. Typical features visible in specimens such as this include:

• Moderately involute coiling, with inner whorls partially concealed by the outer shell.
• Fine, regular ribbing that radiates from the umbilicus to the outer margin, often branching as it approaches the venter.
• A relatively compressed whorl section, lending the ammonite a streamlined appearance.
• Distinct suture patterns, with intricate lobes and saddles marking the internal chamber divisions.

These details not only aid in the identification of the species but also add to the specimen’s aesthetic and scientific appeal.

Biozone and Stratigraphic Significance

Ammonites such as Paracymbytes obsoletus are crucial index fossils, widely used in Jurassic stratigraphy. Within the Sinemurian sequence, their presence helps to define specific ammonite biozones, providing accurate age determinations for the surrounding rock layers. This makes them not only collectible specimens but also scientifically valuable tools in paleontological research.

The Robin Hoods Bay exposures are considered type localities for many Sinemurian ammonites, making specimens from this area highly sought after by both collectors and institutions.

Paleoecology and Ancient Marine Environment

Paracymbytes ammonites were free-swimming marine predators. Their chambered shells allowed buoyancy control, enabling them to move through the water column in search of prey such as small crustaceans and molluscs. The Early Jurassic seas where they thrived were dynamic ecosystems, home to a diverse range of marine reptiles including ichthyosaurs, plesiosaurs, and early crocodilians.

The abundance of ammonites during this period illustrates both their evolutionary success and their importance as a key component of Jurassic marine food chains.

Collector and Display Value

This Paracymbytes obsoletus ammonite fossil from Robin Hoods Bay is a rare opportunity to acquire a specimen from one of the most celebrated Jurassic fossil localities in Europe. The combination of scientific importance, rarity, and aesthetic shell preservation makes it a superb addition to any fossil collection.

Whether for private display, academic study, or as a unique natural history gift, this fossil provides a direct and tangible connection to the marine life of the Early Jurassic seas.

Key Details

• Fossil Type: Ammonite
• Species: Paracymbytes obsoletus
• Age: Sinemurian Stage, Early Jurassic (199–190 million years old)
• Origin: Robin Hoods Bay, Yorkshire, United Kingdom
• Distinct ribbing and coiling typical of the genus
• Supplied with a Certificate of Authenticity
• Exact specimen shown in photographs with 1 cm scale cube

This exceptional ammonite fossil embodies the geological and paleontological richness of the Yorkshire coast, offering collectors the chance to own a piece of Jurassic history.