Although the fossil record contains insects as far back as 400 million years ago in the Devonian Period, the Coleopterans/beetles did not evolve until much later.  Interestingly, the earliest fossils of Coleopterans in the geologic record come from the middle of the Permian period, roughly 245 to 286 million years ago (m.y.a.).  These Permian Protocoleopterans resembled modern reticulated beetles of the family Cupedidae.  During the Mesozoic era many Protocoleopterans became extinct, with only 4 species from 2 genera being present today in North America.

Beetles continued to evolve and  by the middle of the Triassic (245 to 208 m.y.a.) all four sub-orders of modern beetles were established.  During the Jurassic (208 - 146 m.y.a) all super-families present today had developed and many families of beetles had developed their present day appearance.  With the appearance of flowering plants in the Cretaceous, beetle development kicked into high gear.  The earliest beetles found in amber are from the Cretaceous.  Fossil beetles from the Pleistocene (1.8 m.y.a to 11,000 years ago) and Holocene (11,000 years ago to present) epochs are identical to contemporary beetles.

The majority of fossilized insects are found in amber/resinite (fossilized tree sap), in fine grained muddy rocks or shale (Green River Formation, Colorado, USA) and in asphalt deposits (La Brea Tar Pits, California, USA).  In general beetle fossils are plentiful and well preserved due to the beetles hardy exoskeleton.

Fossil Snout Beetle

Fossil Checkered Beetle

Fossil Rove Beetle