Insect

Subclass: Apterygota

Fossils and evolution

The relationships of insects are unclear. Although traditionally grouped with millipedes and centipedes, evidence has emerged favoring a relationship with the crustaceans. Insects first appear in the fossil record during the Carboniferous age, about 350 million years ago. Types included several orders now extinct, and some insects larger than any living today. Little is known about the origin of insect flight, since the earliest winged insects appear to be capable fliers. Wings themselves are now thought to be highly modified gills, and some insects had an additional pair of winglets attaching to the first segment of the thorax, for a total of three pairs.

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The Permian, around 270 million years, saw the development of most extant orders; many of these groups became extinct during the Permian-Triassic extinction event, the largest mass extinction in the history of the earth. The remarkably successful hymenopterans appeared in the Cretaceous but achieved their diversity more recently, in the Cenozoic.

Related Topics:
Permian - Permian-Triassic extinction event

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Many modern insect genera developed during the Cenozoic; from this period on we find insects preserved in amber, often in perfect condition and easily compared with modern species.

Related Topics:
Cenozoic - Amber

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The study of fossilized insects is called paleoentomology.

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