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During the late Paleozoic era the Earth was, if not exactly ruled or terrorised, at the least very seriously bothered by swarms of gigantic dragonflies with wingspans around 70cm across. The monster insects will have been all the more troublesome as dragonflies "need to hunt live prey", according to experts.
Dr John VandenBrooks, after a lengthy struggle, managed to breed enlarged dragonflies in his Arizona laboratory. The large size was achieved by enhancing atmospheric oxygen levels to 31 per cent, as seen in the Paleozoic (today's air is only about 20 per cent O2).
The hard bit, according to the prof, was not the creation of this artificially enriched (or "hyperoxic") atmosphere but the actual care and feeding of the monstrous, prehistoric winged flesh-eaters.
LINK (Via: The Register)
Vandenbrooks dragonflies are only 15% larger than our modern day variety but we all know how that Jurrasic Park thing turned out.