The predatory dinosaur Velociraptor mongoliensis is one of the most recognized creatures from the Late Cretaceous period, yet its anatomical features are often misunderstood due to popular culture portrayals. These feathered, turkey-sized predators possessed complex physical structures that differed significantly from their fictionalized versions. One of the most common questions concerns the structure of its forelimbs and the number of digits it actually had. This inquiry requires a detailed look into the fossil record to understand the design of the raptor’s hands.
The Definitive Answer: Three Digits
Paleontological evidence confirms that Velociraptor, like other dromaeosaurids, possessed three fingers, or digits I, II, and III, on each forelimb. This configuration is a defining characteristic of this group of dinosaurs, often referred to as raptors. The three-digit structure is a reduction from earlier theropods. The fingers were numbered starting from the innermost digit (Digit I), which is comparable to a human thumb, though not truly opposable. Digit I was the shortest and stoutest, while Digit II was typically the longest of the three digits present. This finding corrects the common misconception that these dinosaurs had only two fingers, a configuration seen in some other theropods, such as Tyrannosaurus rex.
Anatomy of the Velociraptor Forelimb
The structure of the Velociraptor hand was influenced by a specialized wrist bone that limited its overall movement. This specialized structure included a semi-lunate carpal, a crescent-shaped bone also found in the lineage leading to modern birds. The semi-lunate carpal acts like a hinge, allowing the hand to flex inward toward the forearm but restricting other movements. This limited mobility meant the forelimb could not rotate the palm downward to face the ground, a movement known as pronation. Instead, the palm was permanently held with the palmar surface facing inward, toward the midline of the body. This orientation is dictated by the bone structure and differs significantly from many artistic depictions. The three digits ended in elongated, strongly curved unguals, which supported the claws. These claws were sharp and built for grasping, though they were not retractable like a modern cat’s. Digit II provided the most leverage and length, while Digit I offered a limited capacity for an opposing grip.
Proposed Functions of the Hands
Given the unique anatomy, paleontologists propose the three-fingered hands were primarily used for securing and handling prey rather than inflicting the initial killing blow. The sharp, curved claws and the ability to fold the hand inward made them well-suited for grappling and holding. This action would allow the raptor to immobilize a struggling animal close to its body, preventing escape. The hands would have been employed to hold the struggling prey close to the predator’s body, allowing the raptor to use its powerful hind legs. The large sickle-shaped claw on the second toe of the foot was likely the primary weapon used to deliver decisive injuries. The inward-facing palms were perfectly positioned to execute this close-range immobilization strategy. Researchers also suggest the forelimbs played a role in stability, possibly during high-speed movement or climbing. The ability to quickly grasp and hold a surface would have provided necessary balance. The three-digit design offered a significant degree of dexterity for various behaviors beyond simply capturing food.