Why Were Dinosaurs So Big?
The Facts and Theories Behind Dinosaur Gigantism
One of the things that makes dinosaurs so appealing to kids and adults is their sheer size: plant eaters like Diplodocus and Brachiosaurus weighed in the neighborhood of 25 to 50 tons, and a well-toned Tyrannosaurus Rex or Spinosaurus tipped the scales as much as 10 tons. From the fossil evidence, it's clear that--species by species, individual by individual--dinosaurs were more massive than any other group of animals that ever lived (with the logical exception of certain genera of prehistoric sharks, prehistoric whales and marine reptiles like ichthyosaurs and pliosaurs, the extreme bulk of which were supported by the natural buoyancy of water).However, what's fun for dinosaur enthusiasts is often what causes paleontologists and evolutionary biologists to tear their hair out. The unusual size of dinosaurs demands an explanation, and one that's compatible with other dinosaur theories--for example, it's impossible to discuss dinosaur gigantism without paying close attention to the whole cold-blooded/warm-blooded metabolism debate.
So what's the current state of thinking about plus-sized dinosaurs? Here are a few more-or-less interrelated theories. Read more...
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