The 10 Biggest Dinosaurs
By Bob Strauss, About.com Guide
Identifying the biggest dinosaurs that ever lived isn't as easy a task as you might think: sure, these giant beasts left giant fossils, but it's very rare to unearth a complete skeleton (tiny, bite-sized dinosaurs tend to fossilize all at once, but lumbering giants like Argentinosaurus can often only be identified by a single, massive neckbone). Here are the 10 winners, according to the current state of paleontological research. (Want to know how big these creatures were? Compare them to the 10 smallest dinosaurs.)
You probably thought the winner in this category would be T. Rex, but it's now believed that Spinosaurus (which had a huge, crocodile-like mouth and a sail of skin jutting up from its back) was slightly heavier, weighing in at 7 or 8 tons. It's possible that this dinosaur's famous sail evolved as a way of increasing its skin area, and hence allowing it to cool down faster--yet more evidence that Spinosaurus was the king of the meat-eaters.
Just as Sauroposeidon is named after the Greek god of the ocean, Quetzalcoatlus is named after the winged Aztec god Quetzalcoatl. This gigantic pterosaur had a wingspan of up to 45 feet, making it the largest creature ever to fly, modern eagles included. That is, if Quetzalcoatlus really did fly: new research hints that this giant pterosaur may have led a completely landbound existence.
With its long, thick, tooth-studded jaws, bulky body, and massive flippers, this pliosaur looked a bit like a cross between an orca and a shark. Paleontologists believe Liopleurodon attained lengths of 40 to 50 feet, and may have weighed 20 to 30 tons, about the dimensions of an adult sperm whale. If this doesn't sound impressive, keep in mind that the biggest great white sharks weigh about 3 tons, max.