The handle of the sturdy wooden door, gleaming in the dim light coming from the windows, shifts its neck downward in an eerie, indicative manner. As the door silently cracks, a glimpse of a slender, scaled monster appears, hissing as it butts its head against the door. With one massive push, the door bursts open and the Velociraptor enters the kitchen where Lex and Tim Murphy are hiding. The kids sit in silence as another Velociraptor enters the room; the raptors roar at each other as if they were communicating. Lex and Tim scamper behind an adjacent counter as the Velociraptors begin to sweep the room, their enlarged claws clicking on the tiles of the floor. Visibly frightened, Lex and Tim tremble as one of the beasts peers its head over the island they cowered behind. Luckily for them, it senses nothing and clicks onward. Then, as if by accident, the raptors massive, muscular tail sweeps across the countertop and sends pots and pans crashing on top of the kids. Lex shrieks as they both dart behind yet another row of counters, but it seems that the raptors take no notice over the crashes and clangs of the pans. It seems they have evaded their predators until Tim flattens himself to the side of cupboard accidentally knocking over a ladle, which seems to stop time on its way to the hard, thunderous ground. Immediately as the utensil makes its deafening ring, both dinosaurs are on the attack: one leaps upon a table as the other makes its way around to the sound of the noise. Lex beckons Tim to follow her to the opposite side, but Tim is frozen in fright. He instantly regrets his decision, though, as one Velociraptor roars as it comes upon the ladle. After their brief inspection of the spoon, they are about to round the corner that would reveal Tim, but Lex manages to catch their attention by banging a ladle of her own against the floor. Now, the raptors turn their attention to her, screeching as Lex tries to barricade herself inside a serving cart. She gets lucky though. One Velociraptor rampages towards her but instead barrels into one of the kitchen’s many reflective surfaces. While that raptor is recovering, Lex makes her escape. Tim, thinking the coast is clear, makes a break for the door. The second raptor is right behind him. He just manages to beat the beast to a closet, and ducks behind its wall, causing the Velociraptor to careen headfirst into a row of shelves. With one raptor inside, Lex and Tim lock the closet door, as the other Velociraptor rises to its feet... (Spielberg, 1993) For most people, this scene from Jurassic Park is the foremost source of information on dromaeosaurs, the biological family to which the aforementioned Velociraptor mongoliensis belongs. Unfortunately, the special effects blockbuster did not give Velociraptors the treatment they were worthy of. In fact, the so-called “Velociraptors” in the film were highly exaggerated, as real Velociraptors were only about the size of a turkey and stood about waist high. If the creators of Jurassic Park were looking for accuracy rather than ferocity when naming the beast that they caricatured, the more than likely would have chosen Deinonychus antirrhopus, another dromaeosaur (Roylance, 2011). The feature of the dromaeosaurs that the filmmakers made a point for their viewers to be aware of was the pair of massive, vicious claws protruding from their second toes. Used in the film to register terror, not only through their terrifying looks, but also through the tense, foreboding “clicks” they made as they crossed the floor, letting the audience know they were always there, these claws are to dromaeosaurs as a pentagonal “S” is to Superman. But were their claws actually used as the savage murder tools they were portrayed to be? The claws of a dromaeosaur were as important to them, as thumbs are to you or I. To illustrate, we’ll take a closer look at the anatomy and biology of the family, how they lived, and finally, where their claws fit in. Dromaeosaurs are a small portion of a group of dinosaurs called theropods: dinosaurs that are bipedal, carnivorous, and had claws that jutted from each of their fingers and toes (Guralnick, 1993). Theropods can be subdivided into two groups: the carnosaurs, immense dinosaurs that have big heads, strong necks, and tiny arms, such as the Tyrannosaurus rex; or the coelurosaurs, lean dinosaurs with smaller heads, long slender necks, and lengthy arms, like the dromaeosaurs (Norman, 1991). The dromaeosauridae are a fascinating group, with many features (aside from their claws) that set them apart from other dinosaurs hailing from the Cretaceous Period. As opposed to carnosaurs like the T. rex, dromaeosaurs arms evolved into flexible, seizing appendages, evidence further supported by their large hands that could have easily been used to grasp (Hutchinson, 1995). Their tails could not be swung to the left or right in a whip-like fashion, as they were only able to bend up and down as exemplified in the picture above. Functioning, then, as a single straight unit, the tail made an efficient balancing mechanism (Tweet, 2011). In fact, Deinonychus’ species identifier, antirrhopus, means “counterbalancing,” and was given in reference to the tail’s utility (Ostrom, 1969). Deinonychus is a particularly intriguing example of the dromaeosauridae family. First discovered in 1964 by Grant Meyer and John Ostrom, these dinosaurs did not fit neatly into either the carnosaurs or the coelurosaurs group (Norman, 1991). Norman said about the specimen, “It was quite small – around 8 ft long – yet it appeared to have a large head and strong neck combined with long grasping arms and strong legs.” (p. 85). Its large head may seem bulky compared to other coelurosaurs, but due to the skull’s cavernous nature, it is actually relatively lightweight. There are a number of large sinuses within the skull that allowed for clever muscle attachments spanning from the jaw to the top of the skull, making their jaw an extremely powerful weapon. To make matters worse for their prey, their serrated teeth pointed backwards, resulting in disastrous tears to muscle and flesh if prey tried to escape a Deinonychus’ bite (Norman, 1991). John Ostrom (1969), the discoverer of Deinonychus made many insightful observations in the paper where he first wrote about it. For instance, the hands of the dromaeosaur were “highly modified to produce precisely limited abduction-adduction and supination-pronation.” This means that Deinonychus’ hands were relatively flexible, especially compared to other theropods. Of course, they were not as maneuverable as a human’s hands, but their specific modifications tailored them so that they could easily grasp and hold on to things. In Ostrom’s words, “These highly sophisticated movements of the wrist are entirely consistent with the raptorial design of the manus (hand).” Another feature that set apart Deinonychus and other dromaeosaurs from the rest of the theropods was their feet, and I’m not necessarily referring to their talons. Deinonychus had four toes: the first was smaller and protruded more from the inner side of the foot, the second had bore the colossal claw, and the third and fourth were similar in size and normal (Ostrom, 1969). The three functioning toes would normally indicate that the dinosaur is tridactyl, meaning it moves and balances using three digits. However, Ostrom hypothesized that the claw on the second toe was only used for predatory reasons and would not typically ever touch the ground, meaning the “clicks” made by the raptors in Jurassic Park were also fictionalized. With the talon never touching the ground, Deinonychus had to adapt to a didactyl stance, placing their weight between digits three and four, as opposed to just digit three, which is normal. Fossils of a dinosaur can only give so much information about them, their behaviors and actions can be difficult to infer from a skeleton. There are, however, uncommon occurrences where dinosaurs are flash-fossilized in so-called “action poses,” giving us a glimpse into how these animals moved and acted. Most commonly, dromaeosaurs are thought to hunt together in packs. In his 1969 discovery of three Deinonychus skeletons alongside one of an herbivorous, quadrupedal Tenontosaurus, Ostrom hypothesized the three predators would have had to work together to take down their 26-foot-long prey (Switek, 2011). On the other hand, Brian Roach and Daniel Brinkman in 2007 contested that the Deinonychus remains found near the Tenontosaurus were, in fact, killed by another Deinonychus in contention for the Tenontosaurus carcass (Switek, 2011). Switek noted that this would make them less pack-oriented, like wolves, and more independent and territorial, like komodo dragons. Whether either premise is correct remains to be seen, as behavior cannot be very well interpreted from mere skeletons. However, Switek went on to write about a 2008 find of tracks similar to that of a Deinonychus in Shandong, China by Rihui Li. Li described the footprints of at least six dromaeosaurs in the same bedding plane, moving in the same direction. The evidence unearthed by Li is supported by another mass of tracks found by Alexander Mudroch in 2011. Mudroch depicted a pair of trackways made by Deinonychus-sized dinosaurs advancing in the same direction (Switek, 2011). Finds such as these give insight to the behavior of the prehistoric beasts, and, with multiple similar trackways found, it would seem that Deinonychus worked in packs. While fossil records can indicate a great deal about the way Deinonychus lived, they still leave a lot up for interpretation. Being as it is virtually impossible to see a living, breathing dinosaur and study it’s daily activities, many scientists and paleontologists have brought a few theories into fruition. Scores of these theories explore the mystery as to why dromaeosaurs evolved such an enlarged, vicious claw. Kenneth Carpenter (2009) developed his theory based on the infamous “Fighting Dinosaurs” specimen discovered by the Polish-Mongolian excavation team of Kielan-Jaworowska and Barsbold in 1972 in southern Mongolia. The specimen depicts a Velociraptor mongoliensis trying to take down a sheep-sized Protoceratops andrewsi. In the midst of the struggle, the Velociraptor got its right arm caught in the Protoceratops’ beak, while it tried to tear at the Protoceratops’ face with its left arm. To gain footing on the Protoceratops, the raptor managed to pierce the neck of the beast with its large talon, cutting off a sizeable amount of blood to the Protoceratops’ head (Kielan-Jaworowska & Barsbold, 1972). Carpenter (2009) believes the two were fossilized in this position because the Velociraptor succeeded in killing its prey, but the Protoceratops, dying, trapped the raptor beneath it, where it, too, eventually died. Carpenter (2009) explains Ostrom’s (1969) view of dromaeosaur claws as the dromaeosaur “caught and held the prey in its fore hands and disemboweled it with the large pedal talon.” However, Carpenter disagrees with Ostrom by arguing the claw’s use as a piercing tool, as opposed to a cutting one. He cites the “Fighting Dinosaurs” specimen by claiming that because the Velociraptor’s talon was embedded in the Protoceratops’ neck, the raptor must have been trying to sever the jugular vein, carotid artery, or trachea (Carpenter, 2009). Another fact that Carpenter brings up is the lack of a razor edge on the underside of dromaeosaurs’ talons. As shown in the figure on the previous page, cross sections of these two dromaeosaurs’ claws reveal that their edges are no sharper than a butter knife. Combined with the information that modern day predators that attack with claws, like hawks or cats, use them to pierce and hold prey makes the case for dromaeosaurs’ talons to be used as a puncturing tool very legitimate (Carpenter, 2009). A different theory, presented by the team of Fowler, Freedman, Scannella, and Kambic (2011), expresses that the claws were only used in a minor part of a dromaeosaurs’ killing process. They relate dromaeosaurs’ killing process, Deinonychus’ specifically, to the methods used by today’s birds of prey. In their description, they assert that a Deinonychus would use its massive talons to anchor itself to a victim it has already pinned down with its bodyweight. Fowler and company maintain that Deinonychus’ killing method was all about stabilization. With its talons affixed to the prey, it would use its long tail to keep balance in combination with “stability flaps” executed by its feathered arms. The flapping motion it employed provided a violent motion to subdue its prey should it have struggled. In between flaps, Deinonychus would lower its forelimbs around its opponent, caging it in. Once the prey was sufficiently subdued, Deinonychus would tear into the prey with its serrated teeth, eating it alive (Fowler et al., 2011). Yet another study suggests the claws were used similarly to the theory presented by Fowler’s team, but with a slight modification. Instead, Manning et al. (2009) describe the claw as being used to climb. This team used X-ray technology to map the stress applied to the claw and found that the majority of pressure applied to the claw is on its underside, which means it was used for support. The photograph to the right indicates where the most amount of stress was applied. Manning and his team also took other measurements, such as the claw’s arc length and the amount of keratin present on the outside of the claw and found them to correlate with the talons and anatomy of modern day climbing birds, like the woodpecker. Finally, the team analyzed the sites of muscle attachments and found them to be well equipped to sustain and distribute weight for vertical motion (Manning et al., 2009). Manning and company went on to describe how this would augment a dromaeosaurs’ killing ability. In this respect, a dromaeosaur would be able to dominate an opponent much larger than itself by climbing onto the prey. The act of scaling the prey is devastating in and of itself: the curvature of the claw would cause it to rotate inside the prey’s body as the dromaeosaur moved upwards, in turn causing massive trauma and tears to muscle tissue (Manning et al., 2009). By doing this, the dromaeosaur could reach a much more vulnerable position, like the back of a quadrupedal herbivore, at which point it could begin the means of eating the victim alive with its teeth and forelimbs. There are many theories as to what the possible uses for the claw are, but I am of the position that every one of them is feasible for a given situation. In an email to me, Justin Tweet (2012) said “there is a fair amount of variation in claw shape, with some animals having straighter claws and others having more curved claws” (thescelosaurus@gmail.com). With so much variation and so many plausible utilities for the talons, I do not think there was one specific use for them; dromaeosaurs would use them as the circumstances called for it. This is one thing I would consider Jurassic Park did right: it depicted dromaeosaurs as being smart and resourceful. They were not the largest dinosaurs, but they made the best of what they had by using their deadly, trenchant talon to its utmost potential. Muldoon readies his weapon, a pump-action, tactical shotgun, as he waits for the Velociraptor to fall victim to his trap. Though the jungle around him is alive with noise, all is silent for Muldoon as he exhales, trying to calm himself before the raptor’s arrival. Bushes just to his left rustle momentarily and, out of the corner of his eye, he sees it. The beast he had been waiting to catch off guard had instead done that exact thing to him. “Clever girl,” he breathes. Those were his last words (Spielberg, 1993).
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Credit: dinocasts.com

Credit: Carpenter (2009)

Credit: Manning et al. (2009)