Dinosaurs were among the most incredible creatures ever to walk this Earth. From small beginnings (around 230 million years ago) they evolved into colossal killers with jaws big enough to swallow a human whole, gigantic plant eaters who shook the ground as they moved, and streamline-bodied sprinters, capable of sprinting at sustained speeds.From the mammoth ARGENTINOSAURUS, which was as heavy as twenty elephants, to the tiny meat-eating MICRORAPTOR, which was smaller than a chicken, here are the dinosaur record breakers. Read about daggerlike fangs, switchblade claws, gigantic skulls, and flesh-ripping horns. Discover how the best-armed dinosaurs deterred their enemies with fearsome suits of armor or how the tallest of the tall stood as high as five-story buildings.