Description
Asteroceras Ammonite Fossil – Black Ven Marls, Lower Lias – Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, UK
This beautiful Asteroceras ammonite fossil comes from the renowned fossil-rich slopes of Stonebarrow Cliff, part of the famous Black Ven Marls on the Jurassic Coast of Dorset. Discovered near Charmouth and Lyme Regis, this specimen originates from the Lower Jurassic period, specifically within the Lower Lias Group, making it approximately 195–200 million years old.
Fossil Type: Ammonite
Species: Likely Asteroceras obtusum (most common in Black Ven deposits)
Order: Ammonitida
Superfamily: Psiloceratoidea
Family: Arietitidae (formerly placed in Asteroceratidae; taxonomic revision applies)
Geological Stage: Lower Jurassic – Hettangian to Lower Sinemurian
Formation: Black Ven Marls Member, Lower Lias Group
Zone: Obtusum Zone (if A. obtusum), common ammonite marker in early Sinemurian
Biozone: Asteroceras obtusum Subzone (where identifiable)
Location: Stonebarrow Cliff, Charmouth, Lyme Regis, Dorset, England
Depositional Environment: Marine shelf setting with fine silt and clay deposition – anoxic conditions favourable to excellent fossil preservation
Morphology Features: Asteroceras is known for its large, thick whorls and coarse, simple ribbing radiating from the umbilicus to the outer edge of the shell. The shell is typically involute with a narrow umbilicus, and may display faint keel development. Well-preserved examples may retain visible suture lines and mineralisation.
Geological Context: The Black Ven Marls are part of the Lower Jurassic Lias succession, a globally significant fossil-bearing sequence of marine sediments. This formation contains abundant ammonites, belemnites, bivalves, and marine reptiles, making it a key biostratigraphic and palaeontological site. The Charmouth-Lyme Regis area is a protected Site of Special Scientific Interest (SSSI) and UNESCO World Heritage Site.
Condition: As shown in photos. Well-preserved fossil with fine detail. Scale rule square/cube = 1cm. Please refer to the photo for full dimensions and authenticity.
Important Note:
All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.
A museum-quality ammonite from one of the world’s most famous fossil locations – perfect for collectors, educators, and lovers of deep time.









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