Insect Fossils Classification with Hexapoda

Unlike the trilobite that has left a prodigious fossil record, the preservation of insects in sedimentary matrix is relatively rare, and essentially limited to the Laggerstat sites. The reason for the scarcity of insect fossil is the poor preservation potential of the insect's exoskeleton. Like other Arthropods, insects have an external skeleton called an exoskeleton. Unlike the thick and calcified trilobite exoskeleton, the insect exoskeleton is made of a thin, plastic-like material called chitin, along with a tough protein. This thin, waterproof covering simple does not preserve well in most oxygenated environments, making insect fossils sparse despite the tremendous number that could have been preserved. The exception is in fossil resinite (amber, by street name), where it is possible for even the minutest details to be preserved. Despite their huge strength to weight ratio, insects were often to small to escape the sticky resin exuded by trees, and which later became a fossil itself, with physical properties akin to modern polymerized plastics.

Insect evolution is a powerful illustration of decent with modification. The earliest known insects are tiny wingless forms from the early and middle Devonian. Insect flight developed with suddenness resembling the Cambrian explosion during the middle Carboniferous, apparently the result of the significant survival advantage that was accrued. By the end of the Carboniferous, the subphylum insecta had evolved into a large number of distinct orders. During the Permian, new insects forms appeared. Blattoid and Orthopteroid orders attained their greatest diversity, and new groups like the Psocoptera, homopteran Hemiptera, Mecoptera and Coleoptera became ubiquitous and diverse. The Permian extinction wiped out nine orders of insects, and more orders disappeared in the Triassic or the early Jurassic. However, surviving orders such as Neuroptera, Mecoptera, and Diptera, and Coleoptera underwent further adaptive radiation establishing many families extant in modern times. So exquisite is insect design that most groups were well formed by the Cretaceous and remain largely unchanged in appearance during modern times.

Insect evolution has led to prodigious diversity of this animal group comapred with other members of Domain Eucarya. For example, there are believed to be three times as many Dipetran species (fllies) as there are vertebrate species, and ten times as many Coliopteran species (beetles) as vertebrate species.

Taxonomic research on fossil insects has always been relegated to a subordinate role when compared to that of living species. There are large numbers of undetermined fossil insects in many collections throughout the world awaiting descriptions, but only a small fraction of systematic research has ever been devoted to these fossils.

Class Insecta Classification with Hexapoda