Written in Bone: Velociraptor

 

The Hollywood blockbuster Jurassic Park series has made Velociraptor one of the most famous dinosaurs in the world. But the real Velociraptor is much different than the movie version, and most of what people know about raptors from the movies is actually wrong.

Velociraptor, in the Los Angeles County Museum of Natural History

In August 1923, during an American Museum of Natural History expedition to the Gobi Desert in Asia, excavators uncovered the crushed but complete skull of a small lightly-built carnivorous dinosaur and, next to it, a sickle-shaped claw which, they assumed, came from the creature’s hand. The find was packed in plaster and sent back to the US for study. At the Museum, paleontologist Henry Fairfield Osborne wrote a paper describing the find, naming it Velociraptor mongoliensis (“the swift robber from Mongolia”). From the length of the skull, the dinosaur would have had a body about the size of a turkey with a long stiff tail, perhaps five feet from nose to tail and standing about 1.5 feet tall at the hips. It probably weighed around 40 pounds. The fossil was not a very notable find, and it was quickly forgotten.

During the Cold War, Mongolia became a satellite country of the Soviet Union, and western scientists were banned from the Gobi fossil sites. Soviet scientists continued to have access, however, and in 1971 they made a spectacular find: the almost complete skeletons of a Velociraptor and a Protoceratops, a dog-sized herbivore related to horned dinosaurs like Triceratops. These two animals had been locked in combat at the time of their death. To their surprise, the paleontologists found that the large sickle claw that had previously been assumed to be a finger claw, was actually a toe claw. The Velociraptor had embedded its sickle claw in the back of the Protoceratops neck, while the herbivore had managed to grasp the carnivore’s forearm in its beaklike jaws. The pair had likely been suddenly buried by a collapsing sand dune as they struggled. Over the years, Soviet and Mongolian scientists found several more specimens of Velociraptor, and when the Soviet Union fell and the Cold War ended in 1990, teams from the US and Canada also began arriving.

By this time, other dinosaurs in the same family as Velociraptor, known as the dromaeosaurs, had been found, and they were a topic of particular interest. In the 1970’s, study of the dromaeosaurs showed them to be fast, agile and active animals, quite unlike the slow plodding reptile-like image that had previously been held about dinosaurs. This new conception led to a renewed debate about dinosaur physiology—if the dinosaurs were active like mammals, did they also have a warm-blooded metabolism like mammals? Soon, with renewed study, several lines of evidence began to converge on the conclusion that at least some of the dinosaurs, including the dromaeosaurs, were indeed warm-blooded. A new picture emerged of the raptors—they were, paleontologists now concluded, active alert intelligent animals that may have lived in social groups and hunted cooperatively in packs.

In the late 1980’s, when writer Michael Crichton was working on his novel Jurassic Park, he was looking for an interesting dinosaur species to serve as his “bad guy”. In paging through some paleontology books, he came across the dromaeosaur group. At this time, two different dinosaur species were included in the Velociraptor genus, and one of these was, at about ten feet in length, larger than the original V mongoliensis, but had the same killing sickle-claw on its feet and was also believed to be a cooperative pack-hunting predator. It suited Crichton’s story perfectly.

It wasn’t until 1993, while Steven Spielberg was adapting Crichton’s novel into a movie, that the Velociraptor genus was reconsidered by scientists; when the larger species Deinonychus was found, it had been afterwards grouped together with the smaller one in the Velociraptor genus. Now, however, Deinonychus was removed and placed back into the original genus of its own. Since Crichton’s protagonist had actually been based on the larger Deinoychus, Spielberg briefly considered renaming his movie dinosaurs as well, but in the end he decided that “Velociraptor” was a much better-sounding name, and though it was no longer scientifically accurate (and even though his fictional dinosaurs were much larger than the actual Deinoychus), the Jurassic Park bad guys remained “Velociraptors”. Ironically, as the movie was in production, a new species of raptor was discovered that matched Spielberg’s movie dinosaur in size—about fifteen feet long and six feet high at the hip, larger than both Velociraptor and Deinonychus. It was named Utahraptor.

But even as Jurassic Park became a worldwide blockbuster movie, the scientific picture of Velociraptor and its relatives was changing yet again. By now, a number of stunning fossils had been found in China which conclusively established that birds had evolved from feathered dinosaurs, and these feathered species of dinosaur were very much like the dromaeosaurs. When paleontologists examined the matter more closely, it became clear that not only were birds and raptors almost identical bone-for-bone, but new fossil discoveries revealed raptor skeletons with unmistakable remains of feathers. In 2007, a well-preserved Velociraptor skeleton showed “quill knobs” on the forearm bones, which are attachment places for feathers. The evidence was clear—Velociraptor had feathers too. The dromaeosaurs were covered with a coating of downy feathers, like a baby bird chick, with a fringe of larger feathers, shaped like those of a modern bird, along its back or forearms. Paleontologists concluded that these small active warm-blooded dinosaurs had evolved their coating of feathers as insulation to conserve body heat, along with a series of showy crests or fringes for sexual or territorial display. It wasn’t until later that feathers became adapted for flight, and the raptors evolved into birds.

When the sequels to the Jurassic Park movie were produced, however, Hollywood story-telling won out over scientific reality (it would take an entire diary to list all the scientific inaccuracies in the movies). The fictional “Velociraptors” remained much larger than the real ones had been. In a nod to science, the movie-makers did apply a crest of quill-like feathers to the back of the male “Velociraptor’s” neck, but the rest of the raptors remained unfeathered. This was done to maintain continuity with the earlier movies. Also, the technology of Computer Generated Imagery (CGI) was not yet powerful enough to animate a realistic-looking coat of feathers, and this simple crest was the best that the special effects department could manage.

Spielberg’s depiction of the raptors as intelligent cooperative and social pack-hunters, however, did accurately reflect scientific thinking of the time. As a whole, the dromaeosaurs (particularly a group known the troodontids) had an unusually large brain for their body size, and it was speculated that they were more intelligent, and probably lived in social groups somewhat like a wolf pack. It was assumed that they acted together to hunt large prey animals, which they brought down by leaping onto them and slashing them open with their sickle-toe killing claw.

Recently, however, this conception has fallen into question, and a new image of the raptors has been proposed—one which is much more birdlike.

In 2010, paleontologist Denver Fowler carried out a detailed comparison of Velociraptor claws and the talons of various birds of prey, and formed a hypothesis that has caught the attention of other scientists. Fowler found that the raptor claws are most similar, in shape and proportion, to birds like the North American Golden Eagle. These birds have an interesting method of capturing prey: they pounce on top of their target, using their body weight to pin it down, and embed their talons into it not to kill, but to hold it in place. The actual killing is then done with the sharp beak. Meanwhile, the birds use flapping motions with their wings to keep themselves balanced as the prey struggles. While this method of killing is best suited for smaller prey, it can also work for larger targets: Golden Eagles have been known to kill young Caribou by embedding their talons into the animal’s back and holding on, allowing the struggling fawn to rip open the wounds in its back until it is exhausted and bleeds to death.

Velociraptor, Fowler proposed, may have used a similar method. The grasping feet with the large sickle-claw would have acted as an anchor, allowing the dinosaur to hold on to its struggling prey while its body weight pinned it down. As the prey animal ripped open its own back, the Velociraptor would be delivering bites with its serrated teeth. And all the while, the dinosaur would be using its feathered arms as balancing rods, flapping them to keep itself upright as the prey struggled beneath it. Fowler points to the famous “Fighting Dinosaurs” fossil as proof that the raptor sometimes attacked prey animals at least as large as itself, such as Protoceratops.

More intriguing, Fowler’s proposal may indicate a pathway from “raptor” to “bird”. Powerful grasping feet with opposable toes could lead to perching feet for standing on tree branches. Balancing flapping motions with feathered arms could lead to the muscle control and aerodynamic feathers that would later lead to powered flight. In essence, the ground-hunting Velociraptor and its relatives were “pre-adapted” for a life as birds. Indeed, some paleontologists have concluded that, since some of the earlier and more primitive dromaeosaurs had full flight feathers and may have been capable of gliding or powered flight, the raptors themselves may actually be the descendants of flying dinosaurs that later became flightless, like ostriches.

So, rather than being the large scaly reptilian pack-hunting wolf of the movies, the real Velociraptor may have been more like a small feathered solitary ground-dwelling hawk or eagle.

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