University of Vermont

Virtual Field Study


Calvert County Fossils

     The faunas of the Miocene Calvert Cliffs in Maryland are known for their rich fossil diversity which includes representatives of all known animal phyla that have hard parts capable of fossilization.  The most recent surveys estimate that the cliffs hold over 624 species of organisms, with 214 of these species belonging to the gastropods (snails), and 187 species belonging to the bivalves (or the clams).  For this study we will be examining the body fossils of two genre of mollusks, Astarte and Anadara
     Astarte and Anadara are identified as bivalve mollusks (clams), that have bodies that are divided into 2 main regions, a head-foot and a mantle (including shell, mantle cavity, and visceral mass).  In bivalves, the muscular foot is the locomotion organ, used for motion, to attach to hard surfaces, or to burrow into the substrate.  Some bivalve genera display sense organs (e.g., tentacles and eyes) on their head, while all members of the Class use the head as the location of their nerve ganglia.  The mantle lines the shell internally; its external edge is the site of shell deposition and growth..  The space between the head-foot and the mantle proper is the mantle cavity, where the anus and external genitalia are located.

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         Bivalve Shell Morphology           Bivalve Internal Anatomy

Last modified October 06 2008 02:40 PM

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