The Rarity of Powered Flight.

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Greetings. The long and storied history of life on Earth is a magnificent story to tell, with the ending nowhere in sight. Billions of life forms have evolved, diversified, and gone extinct, with the process of evolution producing some truly unique species. Amongst the most unique are the powered flyers. 

Powered flight has evolved only four times in the Earth's history; insects, pterosaurs, birds, and bats being the only groups that have attained the capability, each successfully taking to the air, occupying various ecological niches along the way.

Insects acquired powered flight approximately 400 million years ago, during the Devonian Period, however the specific cause of the adaptation is not known to paleontologists. A transition from an aquatic insect to an arboreal form has been offered as a potential explanation. 

Pterosaurs evolved powered flight approximately 228 million years ago, during the Triassic Period, and were the first creatures of substantial size and weight to do so. The largest animals to ever have flown were pterosaurs, with the Cretaceous pterosaur Hatzegopteryx thambema having a wingspan of over 12 meters, with weights of about 250 kilograms. 

Birds, avian dinosaurs, evolved powered flight approximately 150 million years ago, during the Late Jurassic Period, with the appearance of the iconic Archaeopteryx. The specifics of the transition from theropod dinosaurs to birds is still not known, with several theories at play, but the direct lineages have been established beyond a shadow of a doubt. 

Bats are the latest group to evolve powered flight, approximately 60 million years ago, but their sketchy fossil record has made a more detailed study of their evolutionary history quite difficult. 

Interestingly, soaring has been attained by only two groups, the pterosaurs and the birds. The largest species of both groups used their size and massive wingspans to full advantage, with soaring being a far less physically taxing mode of flying. Additionally, the pterosaurs and the bats evolved powered flight on several independent occasions, whilst the fossil record shows that the insects and birds evolved powered flight from a single ancestral form.

Evolutionary processes on full display. 

Thank you for your time and consideration. 

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