Defensive Dinosaur Weapons
The reason prey animals evolve natural defenses is pressure from carnivores; in a world without meat-eaters, herbivores would only develop enough firepower to fight other herbivores for the right to breed. By the end of the Cretaceous period, millions of years of such pressure wielded by tyrannosaurs, raptors, and other fierce hunters produced the most heavily armed prey animals the world has ever seen: ankylosaurs, ceratopsians, and even a few sauropods.
Here's how the herbivorous dinosaurs of the Mesozoic Era defended themselves:
Tails. The long, flexible tails of sauropods had more than one purpose: they helped to counterbalance these creatures' equally long necks, and their ample surface area may have helped dissipate excess heat. However, it's also believed that some sauropods could lash their tails like whips, delivering stunning blows to approaching predators. The use of tails for defensive purposes reached its apex with the ankylosaurs, which evolved heavy, macelike growths at the ends of their tails that could crush the skulls of unwary raptors.
Scales. Until the knights of medieval Europe learned to forge metallic armor, no creatures on earth were more impervious to attack than Ankylosaurus and Euoplocephalus (the latter even had armored eyelids). When attacked, an ankylosaur would plop down onto the ground; the only way its could be killed was if its attacker managed to flip it onto its back and dig into its soft underbelly. By the time the dinosaurs went extinct, even the sauropods known as titanosaurs had developed light armor, which may have helped fend off pack attacks by packs of smaller raptors.
Bulk. One of the reasons sauropods attained such enormous sizes is that plus-sized herbivores are relatively immune to predation: not even a pack of adult Alioramus could hope to take down a 20-ton Shantungosaurus. The downside to this, of course, is that predators shifted their attention to easier-to-pick-off babies and juveniles, meaning that out of a clutch of 20 or 30 eggs laid by a female Diplodocus, only one or two might manage to reach adulthood.
Camouflage. The one feature of dinosaurs that rarely (if ever) fossilizes is their skin color--so we'll never know if (for instance) Protoceratops sported zebra-like stripes, or Maiasaura's mottled skin made it difficult to see in dense underbrush. However, based on analogy with modern prey animals, it would be very surprising indeed if ancient hadrosaurs and ceratopsians didn't sport some kind of camouflage to cloak them from predators' attention.
Speed. Evolution is an equal-opportunity employer: as predators become faster, so do their prey, and vice-versa. While 50-ton sauropods weren't able to run very fast, the average hadrosaur could rear up onto its hind legs and beat a bipedal retreat, and some smaller herbivorous dinosaurs may have been capable of sprinting at 30 or 40 (or possibly 50) miles per hour, especially if they were being chased.
Hearing. As a general rule, predators are endowed with superior sight and smell, while prey animals have acute hearing (so they can run away if they hear an unfamiliar sound in the distance). Based on analysis of their crested skulls, it seems likely that some genuses of hadrosaur (like Parasaurolophus and Charonosaurus) could bellow to each other over long distances, so an individual catching the rustle of an approaching tyrannosaur could warn the entire herd.
Next Page: Intra-Species Weapons
