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Terrestrial invertebrates

The Permian had great diversity in insect and other invertebrate species, including the largest insects ever to have existed. The end-Permian is the largest known mass extinction of insects; according to some sources, it may well be the only mass extinction to significantly affect insect diversity. Eight or nine insect orders became extinct and ten more were greatly reduced in diversity. Palaeodictyopteroids (insects with piercing and sucking mouthparts) began to decline during the mid-Permian; these extinctions have been linked to a change in flora. The greatest decline occurred in the Late Permian and was probably not directly caused by weather-related floral transitions. However, some observed entomofaunal declines in the PTME were biogeographic changes rather than outright extinctions.