Anomia anomialis
Anomia anomialis
Summary
Anomia anomialis was a small jingle shell that lived attached to hard surfaces on the London Clay seabed. It was an attached suspension feeder, staying fixed in place while filtering tiny food particles from seawater passing across its gills.
Like living anomiids, it probably attached by a byssal structure passing through an opening in the lower valve. This allowed it to occupy shells, stones and other firm objects scattered across otherwise soft sediment. Its shell could partly mould itself to the surface beneath it, so individuals were naturally rather variable in shape.
Quick Identification
Look for: a thin, irregular jingle-shell valve with a rounded outline, a more convex upper valve, a flatter lower valve and a byssal notch or opening near the hinge when the attachment valve is preserved.
Diagnostic Features
- Shell is thin and lightweight compared with most London Clay clams.
- Outline is rounded but commonly irregular because growth was influenced by the attachment surface.
- The two valves are unequal, with the upper valve more convex and the lower valve flatter.
- Fine radial striae may be visible on the outer surface but are much weaker than the ribs of strongly ornamented bivalves.
- The lower valve carries the characteristic byssal opening or deep notch used for attachment.
Fossil Details
Similar Species
Recorded Fossil Sites
No fossil-site occurrences have yet been recorded for this species.
References
- Jeffery, P.; Tracey, S. (1997). The Early Eocene London Clay Formation mollusc fauna of the former Bursledon Brickworks, Lower Swanwick, Hampshire. Tertiary Research, 17(3–4), 75–137 View reference