Parksosaurus, a smallish herbivore from the Late Cretaceous of North America. The ridiculously powerful forelimbs may have been used to dig burrows (or enlarge holes co-opted from other critters), although the stiffened end of the tail seems at odds with an extensive fossorial lifestyle. The hind legs are also really well muscled, although whether this was to help the stocky ornithiscian run faster, aid the forelimbs in digging, or perhaps both is up for debate.
Edit: Fixed some details with the feet, and a small cascade of minor changes that were obvious after the fact. The pes claws really are large on this guy, but the toes don't seem to be as large as some had previously suggested (either that or Parks was not a reliable source for measurements, which seems less likely).