Most of the fossils found at Diamond Valley Lake came from relatively small animals. While rodents dominate the small mammal fauna, animals other than rodents are also present, including moles.
Above is a partial claw from a broad-footed mole, Scapanus latimanus. Moles are in the Order Eulipotyphla, a group that includes a variety of animals that used to be placed in the Insectovora (it turns out quite a few of the insectivorans were not closely related to each other, and the grouping is rarely used anymore).
Moles are burrowing mammals, digging tunnels through the soil with large, powerful front feet, as can be seen in these examples of related eastern moles (Scalopus aquaticus) from the North Carolina Museum of Natural Sciences and the Museum of Osteology, respectively:
Moles can live in a variety of conditions, but they are restricted to soils with enough moisture and the correct texture for making their burrows (they don’t live in soil that’s too sandy, for instance), and to areas where there is enough food to sustain them. Like many small mammals moles are voracious predators that eat a significant percentage of their body weight each day, so they require a steady supply of earthworms, insect larvae, snails, and other burrowing invertebrates. Many of these invertebrates have a low preservation potential, but the presence of moles in a deposit hints at their presence.