During last week's Valley of the Mastodons events, museum supporter Doug Shore donated a collection of invertebrate and plant fossils to Western Science Center. Several of Doug's specimens come from Mason Creek, an incredibly rich Carboniferous site in Illinois that is most famous for its beautiful fossil plants. While WSC has a large collection of Mason Creek plants, we did not have any of the numerous animals also found at the site until now.Above are two specimens of the mollusk Aviculopecten mazonensis, a scallop. At least, I think it's two specimens. As the name states, bivalve mollusk have two valves or shells. In many bivalves these two shells look quite different from each other, but in the pectinids (scallops) they are often very similar (although one valve tends to be deeper than the other). In this case the two valves have slightly different dimensions and both seem to have the same curvature, making me suspect they represent two individuals rather than two shells from one individual. Thanks to Doug for this nice addition to the WSC collection!