A beautifully preserved specimen of Promicroceras planicosta, fully replaced by calcite. This ammonite displays fine ribbing and its characteristic planispiral coiling. As a key index fossil of the Lower Jurassic Sinemurian, Promicroceras is highly significant for ammonite biostratigraphy in the UK. An excellent choice for collectors, researchers, or curated display.

Stratigraphic Context

• Lower Lias Group, Obtusum Zone

Chronostratigraphy

• Lower Jurassic, Sinemurian (~200 million years ago)

Provenance

• Charmouth Foreshore, Lyme Regis, Dorset, England (UK Jurassic Coast, UNESCO World Heritage Site)

Preservation

• Calcite-replaced shell with well-defined ribbing and morphological detail

Dimensions

• Ammonite Diameter: 2.5 cm (1 inch)

Collector’s Note
Each specimen is supplied with a species and locality identification label. You will receive the exact ammonite shown #4, carefully hand-selected to meet high standards for research or display.