HAYS, KS -- Tyrannosaurs and other predatory dinosaurs have gotten a bad rap, says Dr. Philip Currie, curator of dinosaurs at the Royal Tyrrell Museum of Paleontology in Drumheller, Alberta, Canada.
Currie spoke on "Hunting Behavior in Predatory Dinosaurs" at Fort Hays State University on Saturday, April 20, in conjunction with the "Jurassic Park: The Life and Death of Dinosaurs" exhibit on display at FHSU's Sternberg Museum of Natural History through May 5.
"Tyrannosaurus rex has been unjustly tried -- and convicted in some cases," he said, "and what I'd like to do is force an appeal on this case."
The "trial" Currie referred to is an ongoing controversy in the scientific community regarding meat-eating dinosaurs: Were they ferocious hunters, as they've traditionally been portrayed, or were they merely scavengers, snacking on whatever remains they happened upon?
After years of studying carnivorous dinosaurs all over the world, Currie inclines toward the first view, but he pointed out that most evidence in the fossil record is far from conclusive. "The only evidence you have for any of this is smoking-gun," he said. "It's really nice if you have a specimen actually being predators."
That smoking gun was discovered in 1981 by a Polish-Mongolian expedition in the form of a fossilized velociraptor devouring a protoceratops. Currie said the protoceratops was probably hiding behind a sand dune during a sandstorm when a hungry velociraptor happened upon it. Although the velociraptor was small, it was aggressive and won the fight, putting a nasty gash in the protoceratops' neck.
Unfortunately for the velociraptor, the protoceratops managed to close its jaws on the velociraptor's foreleg before dying. The velociraptor was unable to escape before sand buried both animals, smothering them to death. Seventy-five million years later, Currie said the remains of this ancient fight are the most conclusive evidence yet of predatory behavior in meat-eating dinosaurs.
His own work on dinosaur fossils in Alberta, Mongolia and Argentina generally supports this conclusion. Currie is considered a world expert on carnivorous dinosaurs; in addition to the popular T. rex, he has studied its close relatives, the Albertosaurus and Daspletosaurus, as well as the Gorgosaurus, another large carnivore. Two years ago in Mongolia he discovered a new specimen of carnivorous dinosaur, the skull of a juvenile Tarbosaurus, which he unveiled Friday at Sternberg Museum.
The Tarbosaurus skull, like tyrannosaurs and other carnivorous dinosaurs, has incredibly powerful jaws capable of crushing bone. But this in itself does not indicate that the dinosaurs were predators, since strong jaws would be necessary for scavenging as well. Currie said tyrannosaurs were probably both scavengers and hunters.
"Almost all meat-eating dinosaurs are opportunists," Currie said. "If they find something dead, they're going to eat it. First of all, it's not going to fight back, and secondly, it's good protein."
However, other evidence supports the idea that dinosaurs were well-adapted for hunting as well. Much of this evidence comes from a bone bed in Alberta that was originally discovered by the paleontologist Barnum Brown in 1910. Currie and his team re-discovered this bed in 1997 by following photographs they found in the American Museum of Natural History.
The bone bed contains the remains of at least 12 albertosaurs, ranging in age from juveniles to mature adults. This extraordinarily high concentration of one type of dinosaurs is strong evidence that the dinosaurs lived together in a herd or pack.
"These animals probably lived together because they died together," Currie said. "When you get large groups of animals together, the chances of some catastrophe like this happening is higher. Animals interfere with each other, they panic, and nasty things start to happen."
Although the exact nature of the catastrophe is still unknown, the bed has yielded many clues to the differences between juvenile and adult dinosaurs. In contrast to the powerfully-built adults, the juveniles are more lightly proportioned, much like the ornithomymids, the fastest dinosaurs to ever live.
To Currie, this suggests that perhaps the quick, agile juvenile dinosaurs served as runners, chasing prey out of a herd so the adult albertosaurs could move in for the kill. Although the adults were slower than the juveniles, he said, they were still probably faster than the duck-billed dinosaurs they preyed upon.
"The important thing for a carnivore is that you're faster than the herbivore," he said. "As long as you can catch your prey, it doesn't matter at what speed that transaction took place."
Another exciting find is a group of seven dinosaur skeletons Currie's team found while digging in Argentina. These dinosaurs, as yet unnamed, represent a new species; the largest skeleton may dethrone the Giganotosaurus as the biggest meat-eating dinosaur known. Of particular interest to Currie is the dinosaur's blade-like teeth, which suggest a different method of feeding than other carnivores.
"These dinosaurs were going after animals much bigger than themselves," he said. "There's no way they could bite through the bones; instead, they bit through the flesh and muscles quickly and repeatedly. It's a different strategy altogether."
Still more evidence about the predatory nature of dinosaurs comes from the skeleton of a T. rex discovered near Drumheller. Currie has done extensive physiological studies of this skeleton to refute the argument that T. rex was too big and awkward to catch prey.
One such argument is that T. rex's skull was overly long and heavy, making quick movement impossible. Currie found that, in fact, the T. rex skull is right in line with other dinosaurs proportionally, but the T. rex has an unusually short body and forelegs to bring the bulk of its mass closer to its center of gravity. The skull also indicates that T. rex had stereoscopic vision, with both eyes set together on the front of the head.
"If T. rex was a scavenger, why on earth would it need stereoscopic eyes?" Currie said.
There is also strong evidence that T. rex had an excellent sense of smell, based on the size of the olfactory lobes of the brain. Currie said that, contrary to what some experts have suggested, this heightened sense would be as valuable to a predator as to a scavenger. "It's going to help you find your food either way," he said.
Overall, he said, all the evidence is either inconclusive or supports predation. "We don't really know at this stage if Tyrannosaurus and Albertosaurus and Tarbosaurus and all the others were scavengers or predators," he said. "The evidence suggests they were probably both. But these animals were built to be hunters."
After the lecture, Currie conducted a brief question-and-answer period with members of the audience, including about a dozen pre-teen boys. One young man asked Currie how old he was when he first became interested in studying dinosaurs.
Currie said "the big turning point" was at age 11, when he read All About Dinosaurs by R.C. Andrews. He decided that day he wanted to be a paleontologist and study dinosaurs, a decision he's never since regretted.
"They're absolutely wonderful animals to work on," he said, "and I'll continue working on them and loving every minute of it."