Fossil evidence exists of giant prehistoric insects. Dragonfly-like creatures Meganeura monyi and Meganeuropsis permiana flew on wings 75cm across during the Permian (299\u2013252 million years ago) and Carboniferous (359\u2013299 MYA).<\/p>\n

Various theories can explain the supersizing. First, that higher oxygen levels in the atmosphere (30 per cent then versus 20 per cent now) allowed the insects\u2019 energy needs to be met, even though gas exchange was limited along narrow breathing tubes by passive diffusion.<\/p>\n

Dinosaur mass extinction: what caused it, which dinosaurs went extinct, and how mammals survived<\/a><\/strong><\/li>\n
Why did dinosaurs get so big?<\/a><\/strong><\/li>\n
Five British dinosaurs you\u2019ve (probably) never heard of<\/a><\/strong><\/li>\n<\/ul>
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Second, that oxygen is toxic at high concentrations (especially to aquatic larvae), so growing larger diluted the effects of the gas. And third, that insects were at the top of the airborne food-chain in a time before birds. Lacking any serious predators, they grew large, just like wetas in predator-free New Zealand, elephant birds on Madagascar and tortoises on the Gal\u00e1pagos.<\/p>\n
Main image: Computer artwork of giant Meganeura resting on a log in a forest, during the Carboniferous period. \u00a9 Mark Garlick\/Getty Images\u00a0<\/em><\/p>\n
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By Richard Jones Published: Tuesday, 27 September 2022 at 12:00 am Fossil evidence exists of giant prehistoric insects. Dragonfly-like creatures Meganeura monyi and Meganeuropsis permiana flew on wings 75cm across during the Permian (299\u2013252 million years ago) and Carboniferous (359\u2013299 MYA). Various theories can explain the supersizing. First, that higher oxygen levels in the atmosphere […]<\/p>\n","protected":false},"author":24,"featured_media":20880,"template":"","categories":[1],"acf":{"readingTimeMinutes":"< 1"},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2022\/09\/why-were-prehistoric-insects-so-large.jpg",2008,1493,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2022\/09\/why-were-prehistoric-insects-so-large-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2022\/09\/why-were-prehistoric-insects-so-large-300x223.jpg",300,223,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2022\/09\/why-were-prehistoric-insects-so-large-768x571.jpg",768,571,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2022\/09\/why-were-prehistoric-insects-so-large-1024x761.jpg",800,595,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2022\/09\/why-were-prehistoric-insects-so-large-1536x1142.jpg",1536,1142,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2022\/09\/why-were-prehistoric-insects-so-large.jpg",2008,1493,false]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcwildlife\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"By Richard Jones Published: Tuesday, 27 September 2022 at 12:00 am Fossil evidence exists of giant prehistoric insects. Dragonfly-like creatures Meganeura monyi and Meganeuropsis permiana flew on wings 75cm across during the Permian (299\u2013252 million years ago) and Carboniferous (359\u2013299 MYA). Various theories can explain the supersizing. First, that higher oxygen levels in the atmosphere…","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/rss_feed\/20879"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/rss_feed"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/types\/rss_feed"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/users\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/media\/20880"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/media?parent=20879"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/categories?post=20879"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}