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TF0105 - Gryphaea dilatata
Species
Gryphaea dilatata
Stratigraphic Range
Jurassic
Taxonomy
Phylum: Mollusca
Class: Bivalvia
Order: Ostreoida
Family: Gryphaeidae
Class: Bivalvia
Order: Ostreoida
Family: Gryphaeidae
Distinctive Features
Umbo
Growth lines
Two articulated valves
Growth lines
Two articulated valves
Preservation
Mineral replacement of shell
Advanced notes
Asymmetric valves distinctive for Gryphaeidae - flat upper (right) valve and curved lower (left) valve. With this shape Gryphaea reclined in the sediment, filter feeding.
Repair scars are visible on most Gryphaea specimens. When the animal was attacked unsuccessfully by a predator, a small amount of a growth line at the edge of the shell would have been chipped away. The next growth line would have filled in the missing part of the shell, leaving an uneven growth line pattern, with a 'v' or 'u' shape visible.