Three hundred million years ago there was a period of global warming. Two hundred million years ago, dinosaurs roamed the land, wreaking havok and spreading terror. Scientists think the two events were intimately linked.
Around three hundred million years ago, the world was a very different place. North America and Europe had a firm grip on the equator, and hadn't yet slipped upwards toward the north pole. Their equatorial placement gave the two land masses a steamy, tropical climate and lush rainforests. Sadly, trouble was brewing in paradise. The world was becoming a hotter place. Rain stopped falling, and the rainforests dried up. The long, continuous rainforests split into small patches of forest, cut off from each other by dry, impassable countryside.
This countryside isolated forests as completely as an ocean separates islands. Just as islands isolation from each other cause divergent species to evolve on them, the forests isolation caused divergent evolution of certain species. The most successful species were reptiles. Cut off from each other, facing adverse conditions, they evolved in disparate and fascinating ways . . .
And 100 million years they made the earth tremble with their footsteps. That's right, the diversity bred in that first environmental collapse appears to have started a chain that led to some of the most terrifying and fearsome predators in the planet's history. Although many links in that ancient chain are not present in the modern world, the lesson is still clear: don't mess with the earth's climate or a T-Rex might eat you.