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Modiolopsis
fossil clam genus
Modiolopsis, extinct genus of pelecypods (clams) found as fossils in Ordovician rocks (about 488 million to 444 million years old). Its form and structure is distinct, with a shell roughly elliptical in outline and broader at the margins. Markings on the shell consist of prominent growth lines in an arcuate or concentric pattern. Modiolopsis is a useful guide fossil for Ordovician rocks.
This article was most recently revised and updated by Richard Pallardy.
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