Palaeopagurus is an extinct genus of hermit crab from the Lower Cretaceous. A fossil of the species P. vandenengeli is notable for having been preserved in situ in the shell of an ammonite. Along with a lack of fossils of hermit crabs in gastropod shells from before the Late Cretaceous, this suggests that ammonite shells may have played a more important role in the early evolution of hermit crabs' characteristic shell-dwelling habits.