The youngest of the Chesapectens is the C. septenarius. It is different from older pectinidae in that it has a more symmetric hinge. It is smaller than most of its older cousins by more than 30% (from about 2cm to 10cm) and the lower valve is a bit flatter. No articulated specimens were found so I have chosen 2 valves that are fairly close to each other in size.
