If you had several shells in front of you do you think you could tell them apart? When it comes to the shell of a bivalve there are not a lot of obvious features that can be measured. Two features that have been identified and quantified are changes in shell thickness and interval volume. In order to study the change in shell morphology over time, shells must be collected from horizons spanning a range of rock ages at an outcrop. Once those shells are collected they must then have their interval volume and shell thickness documented. The quantification of these features is done in a laboratory with a pair of calipers, some fine sand, and a cylinder.
