cockroaches were an ancient group of insects that arose during the Devonian period. Fossil roachoids that lived during that time differ from modern cockroaches in that they had long external ovipositors and are the ancestors of mantises, as well as modern cockroaches. As the body, hind wings and mouthparts are not preserved in fossils frequently, the relationship of these roachoids and modern cockroaches remains disputed. The first fossils of modern cockroaches with internal ovipositors appeared in the early Cretaceous. A recent phylogenetic analysis suggests that cockroaches originated at least in the Jurassic. The evolutionary relationships of the Blattodea (cockroaches and termites) shown in the cladogram are based on Inward, Beccaloni and Eggleton (2007). The cockroach families Anaplectidae, Lamproblattidae, and Tryonicidae are not shown but are placed within the superfamily Blattoidea. The cockroach families Corydiidae and Ectobiidae were previously known as the Polyphagidae and Blattellidae. Termites were previously regarded as a separate order Isoptera to cockroaches. However, recent genetic evidence strongly suggests that they evolved directly from 'true' cockroaches, and many authors now place them as an "epifamily" of Blattodea. This evidence supported a hypothesis suggested in 1934 that termites are closely related to the wood-eating cockroaches (genus Cryptocercus). This hypothesis was originally based on similarity of the symbiotic gut flagellates in termites regarded as living fossils and wood-eating cockroaches. Additional evidence emerged when F. A. McKittrick (1965) noted similar morphological characteristics between some termites and cockroach nymphs. The similarities among these cockroaches and termites have led some scientists to reclassify termites as a single family, the Termitidae, within the order Blattodea. Other scientists have taken a more conservative approach, proposing to retain the termites as the Termitoidae, an epifamily within the order. Such a measure preserves the classification of termites at family level and below. Description Most species of cockroach are about the size of a thumbnail, but several species are larger. The world's heaviest cockroach is the Australian giant burrowing cockroach Macropanesthia rhinoceros, which can reach in length and weigh up to . Comparable in size is the Central American giant cockroach Blaberus giganteus. The longest cockroach species is Megaloblatta longipennis, which can reach in length and across. A Central and South American species, Megaloblatta blaberoides, has the largest wingspan of up to . At the other end of the size scale, Attaphila cockroaches that live with leaf-cutter ants include some of the world's smallest species, growing to about