Science As prehistoric birds emerged, giant insects departed (+video)

As the first birds took to the skies about 150 million years ago, huge insects started to decline, say scientists. 

Wolfgang Zessin and Matthew Clapham

Millions of years ago, oversized insects like griffinflies boasting wingspans comparable to today's hawks scuttled across (and fluttered above) the planet. But why these jumbo jets of the insect world shrunk to modern size has remained a mystery, until now.