Mark Wilson May 27th, 2010
NEW ALBANY, MISSISSIPPI — The Cretaceous oyster above was collected from the Coon Creek Beds of the Ripley Formation (Upper Cretaceous) near Blue Springs, Mississippi. The holes are borings called Entobia which were produced by clionaid sponges which built a network of connected chambers inside the shell so that they could carry out their filter-feeding with some safety from grazing predators. The branching white fossil is a cyclostome bryozoan, probably Voigtopora thurni. Which was present first on the shell, the borings or the bryozoan? Is there evidence that they were living at the same time? The largest holes are about two millimeters in diameter.