How Did Dinosaurs Fight?

Teeth, Claws, Tails and Talons - All About Dinosaur Combat

Kentrosaurus defends itself against an Allosaurus attack (Alain Beneteau).

In Hollywood movies, dinosaur fights have clear winners and losers, carefully demarcated arenas (say, an open patch of scrubland or the cafeteria in Jurassic Park), and usually a bunch of scared-out-of-their-wits human spectators. In real life, though, dinosaur fights were more like confused, chaotic bar brawls than Ultimate Fighting matches, and rather than persisting for multiple rounds, they were usually over in the blink of a Jurassic eye.

(See a list of the Deadliest Dinosaurs, as well as Prehistoric Battles featuring your favorite dinosaurs, reptiles and mammals.)

It's important at the outset to distinguish between the two main types of dinosaur combat. Predator/prey encounters (say, between a hungry Tyrannosaurus Rex and a lone, juvenile Triceratops) were quick and brutal, with no rules except "kill or be killed." But intra-species clashes (say, two male Pachycephalosaurus head-butting each other for the right to mate with available females) had a more ritualistic aspect, and rarely resulted in a combatant's death (though one presumes serious injuries were common).

Of course, in order to fight successfully, you need to be equipped with suitable weapons. Dinosaurs didn't have access to firearms (or even blunt instruments), but they were endowed with naturally evolved adaptations that helped them either to hunt down their lunch, avoid being lunch, or propagate the species in order to restock the global lunch menu.

Offensive weapons (like sharp teeth and long claws) were almost exclusively the province of meat-eating dinosaurs, which preyed on one another or on gentler herbivores, while defensive weapons (like armor plating and tail clubs) were evolved by plant-eaters in order to fend off attacks by predators.

A third type of weapon consisted of sexually selected adaptations (such as sharp horns and thickened skulls), wielded by the males of some dinosaur species in order to dominate the herd or compete for the attention of females.

Offensive Dinosaur Weapons

Teeth. Meat-eating dinosaurs like T. Rex and Allosaurus didn't evolve big, sharp teeth merely to eat their prey; like modern cheetahs and great white sharks, they used these choppers to deliver quick, powerful, and (if they were delivered in the right place at the right time) fatal bites. We'll never know for sure, but reasoning by analogy with modern carnivores, it seems likely that these theropods aimed for their victims' necks and bellies, where a strong bite would cause the most damage.

Claws. Some carnivorous dinosaurs (like Baryonyx) were equipped with large, powerful claws on their front hands, which they used to slash at prey, while others (like Deinonychus and its fellow raptors) had single, oversized, curved claws on their hind feet. It's unlikely that a dinosaur could have killed prey with its claws alone; these weapons were probably also used to grapple with opponents and keep them in a "death grip." (Bear in mind, however, that huge claws don't necessarily connote a carnivorous diet; the big-clawed Deinocheirus, for example, was a confirmed vegetarian.)

Eyesight and smell. The most advanced predators of the Mesozoic Era (like the human-sized Troodon) were equipped with large eyes and relatively advanced binocular vision, which made it easier for them to zero in on prey, especially when hunting by night. Some carnivores also possessed an advanced sense of smell, which enabled them to scent prey from far off (though it's also possible that this adaptation was used to home in on already-dead, rotting carcasses).

Momentum. Tyrannosaurs were built like battering rams, with enormous heads, thick bodies, and powerful hind legs. Short of delivering a fatal bite, an attacking Daspletosaurus could knock its victim silly, provided it had the element of surprise on its side and a sufficient head of steam. Once the unlucky Stegosaurus was lying on its side, stunned and confused, the hungry theropod could move in for the quick kill.

Speed. Speed was an adaptation shared equally by predators and prey, a good example of an evolutionary "arms race." Since they were smaller and more lightly built than tyrannosaurs, raptors and dino-birds were especially quick, which created an evolutionary incentive for the plant-eating ornithopods they hunted to run faster as well. As a rule, carnivorous dinosaurs were capable of short bursts of high speed, while herbivorous dinosaurs could sustain a slightly less brisk pace for a longer period of time.

Bad breath. This may sound like a joke, but paleontologists believe that the teeth of some tyrannosaurs were shaped so as to purposely accumulate shreds of dead tissue. As these shreds rotted, they bred dangerous bacteria, meaning any non-fatal bites inflicted on other dinosaurs would result in infected, gangrenous wounds. The unlucky plant-eater would drop dead in a few days, at which point the responsible Carnotaurus (or any other predator in the immediate vicinity) chowed down on its carcass.

Defensive Dinosaur Weapons

Tails. The long, flexible tails of sauropods and titanosaurs had more than one function: they helped to counterbalance these dinosaurs' equally long necks, and their ample surface area may have helped dissipate excess heat. However, it's also believed that some of these behemoths 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, or armored dinosaurs, which evolved heavy, macelike growths at the ends of their tails that could crush the skulls of unwary raptors.

Armor. 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, these ankylosaur would plop down onto the ground, and the only way they could be killed was if a predator managed to flip them onto their backs and dig into their soft underbellies.

By the time the dinosaurs went extinct, even titanosaurs had evolved a light armored coating, which may have helped fend off pack attacks by packs of smaller raptors.

Sheer bulk. One of the reasons sauropods and hadrosaurs attained such enormous sizes is that full-grown adults would have been virtually 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, was 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 Protoceratops sported zebra-like stripes, or if Maiasaura's mottled skin made it difficult to see in dense underbrush. However, reasoning by analogy with modern prey animals, it would be very surprising indeed if hadrosaurs and ceratopsians didn't sport some kind of camouflage to cloak them from the attention of predators

Speed. As mentioned above, evolution is an equal-opportunity employer: as the predatory dinosaurs of the Mesozoic Era become faster, so do their prey, and vice-versa. While a 50-ton sauropod couldn't have run very fast, the average hadrosaur could rear up onto its hind legs and beat the bipedal retreat in response to danger, and some smaller plant-eating dinosaurs may have been capable of sprinting at 30 or 40 (or possibly 50) miles per hour while being chased.

Hearing. As a general rule, predators are endowed with superior sight and smell, while prey animals possess acute hearing (so they can run away if they hear a threatening rustle in the distance). Based on an analysis of their crested skulls, it seems likely that some duck-billed dinosaurs (like Parasaurolophus and Charonosaurus) could bellow to each other over long distances, so an individual hearing the footsteps of an approaching tyrannosaur would be able to warn the herd.

Intra-Species Dinosaur Weapons

Horns. The fearsome-looking horns of Triceratops may only have been secondarily intended to warn away a hungry T. Rex. The position and orientation of ceratopsian horns leads paleontologists to conclude that their main purpose was in dueling with other males for dominance in the herd or breeding rights. Of course, unlucky males might be wounded, or even killed, in this process--researchers have unearthed numerous dinosaur bones bearing the marks of intra-species combat.

Frills. The giant head ornaments of ceratopsian dinosaurs served two purposes. First, oversized frills made these plant-eaters look bigger in the eyes of hungry carnivores, which might opt to concentrate on smaller fare instead. And second, if these frills were brightly colored, they could have been used to signal the desire to fight during mating season. (Frills may also have had yet another purpose, as their large surface areas helped to dissipate and absorb heat.)

Crests. Not quite a "weapon" in the classic sense, crests were protrusions of bone most often found on duck-billed dinosaurs. These backward-pointing growths would have been useless in a fight, but they may well have been employed to attract females (there's evidence that the crests of some Parasaurolophus males were larger than those of the females). As mentioned above, it's also likely that some duck-billed dinosaurs funneled air through these crests as a way of signaling to others of their kind.

Skulls. This peculiar weapon was unique to the family of dinosaurs known as pachycephalosaurs ("thick-headed lizards"). Pachycephalosaurs like Stegoceras and Sphaerotholus sported up to a foot of bone on the tops of their skulls, which they presumably used to head-butt one another for dominance in the herd and the right to mate. There's some speculation that pachycephalosaurs may also have butted the flanks of approaching predators with their thickened domes.