Documenting Evolution In Calvert County
Work by Patricia Kelley (University of North
Carolina, Wilmington) best documents the evolution of numerous
fossilized organisms in the Calvert Cliffs strata. The data presented in
this Virtual Field Study is a small subset of the extensive data set published by Kelley
(1989), Evolutionary Trends Within
Bivalve Prey of Chesapeake Group Naticid Gastropods
(Historical Biology, vol. 2, pp. 139-156). Dr.
Patricia Kelley, former doctoral student of Stephen J. Gould, examined
trends in
changing shell characteristics of several genre of bivalve
mollusks. Kelley sampled over 3,000 shells per genera through the
Calvert, Choptank, and St. Mary's Formations. As she
examined changing shell features in several genera tested, Dr. Kelley
was
able to document two features on two genera of mollusks that
demonstrated significant gradual change over time. Those two
genre were Astarte and Anadara, and in this module we will present some of Dr. Kelley's data to demonstrate evolution.