(c) Exoskeletons include insects such as grasshoppers and cockroaches, and crustaceans such as crabs and lobsters. Fossil evidence suggests that the first insects lived about 412 million years ago, during the Early Devonian Period. The origin of the reptiles lies about 320–310 million years ago, in the swamps of the late Carboniferous period, when the first reptiles evolved from advanced reptiliomorph labyrinthodonts. The earliest-known eutherian mammal hunting on a tree fern. A shrew-like animal that snagged insects from ferns lining the shores of freshwater lakes 160 million years ago.