By Devin Powell
A prehistoric prequel to Godzilla took place about 150 million years ago, when insects of monstrous size met their doom battling the ancestors of modern birds.
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The epic struggle ended an era of insect growth spurts that coincided with upticks in the amount of oxygen in the air. Starting with the Cretaceous period, predators kept the sizes of insects down, researchers report online June 4 in the Proceedings of the National Academy of Sciences.
“That’s when birds evolved and started to become better at flying,” says Matthew Clapham, a paleontologist at the University of California, Santa Cruz. “Even though oxygen continued to increase during that time, the insects got smaller.”