Article: Mode of life and autecology of Silurian–Devonian Grammysiidae (Bivalvia)
The Grammysiidae are a Palaeozoic family of mainly infaunal anomalodesmatan Bivalvia that lived in very shallow marine environments. Since they were edentulous, the problem of shearing of the valves during burrowing was overcome by the cincture (radial furrows and ribs), which folded the ventral margin. This folded venter provided an active saw during burrowing. Species that burrowed in very high-energy environments showed very marked ventral folding, strong concentric ribs on the anterior end, a fairly large anterior end, and usually a disc-shaped, not highly inequilateral, shell of low inflation. Byssally attached forms reduced the anterior end, expanded the posterior end, had a less folded venter, more elongate shell, lost the strong anterior concentric ribbing, and were more inflated. Shell form and ornamentation is related to the environment and mode of life.