Arctica morrisii
Arctica morrisii
Summary
Arctica morrisii was a robust marine clam that lived in Palaeogene seas. Its thick, inflated shell is consistent with a life partly or fully buried in soft sediment. Comparison with living arcticid clams suggests it was probably an infaunal suspension feeder, drawing seawater across its gills to collect plankton and other suspended organic particles.
Living beneath the seabed would have helped protect the animal from disturbance and predators, while its sturdy shell provided additional defence. Fossils occur as shell material and moulds, giving us a record of one of the larger burrowing bivalves in these marine communities.
Quick Identification
Look for: a thick, inflated, rounded-to-subtrigonal clam shell or mould with prominent umbones and mainly concentric growth sculpture; confirm the overall proportions and hinge where preserved before assigning a fragment to species.
Diagnostic Features
- Shell is thick, inflated and rounded to subtrigonal in overall outline.
- Umbones are prominent and positioned anterior to the shell midline.
- Exterior is dominated by concentric growth lines and ridges rather than strong regular radial ribs.
- Hinge is robust, and preserved hinge characters are important for separating similar arcticid shells.
- Species-level identification should combine shell proportions, convexity and hinge detail; incomplete feature-poor moulds are not diagnostic.
Fossil Details
Similar Species
Recorded Fossil Sites
Reculver Sand Member
Synonyms & Previous Names
References
- MolluscaBase Editorial Board. (2026). MolluscaBase: Arctica morrisii (J. De C. Sowerby, 1841). MolluscaBase View reference
- Ward, D.J. (1978). The Lower London Tertiary (Palaeocene) succession of Herne Bay, Kent. Report of the Institute of Geological Sciences. Institute of Geological Sciences View reference