Insects are arthropods belonging to the Insecta class. The oldest insect fossils date from the Devonian Period (417 to 354 million years ago). However, during the more recent Carboniferous Period (354 to 290 million years ago) various kinds of insects appeared all of a sudden. For instance, cockroaches appear suddenly complete with the structures they still have today. Betty Faber of the American Museum of Natural History says that 350-million-year-old cockroach fossils are identical with those of today. (M. Kusinitz, Science World, 4 February 1983, p. 1.) The 125-million-year-old fossil in the picture is evidence that cockroaches have not evolved for hundreds of millions years.