Factoid of the Week, Exhibit Spotlight: Deinonychus antirrhopus
Factoid of the Week February 18
Exhibit Spotlight: Deinonychus antirrhopus
After Jurassic Park catapulted Velociraptor into pop stardom, many among the general public tend to conflate all small meat-eating dinosaurs with the raptor group (technically they’re known as the maniraptors, which means “grabby hands”). To continue our survey of the small carnivorous theropods of the park, let’s check out Deinonychus.
Up until the discovery of Utahraptor in 1993, Deinonychus weighed in as the real bruiser of the raptor clan at up to 11 feet and a whopping 150-225 pounds. Since the discoveries of giant raptors like Utahraptor, Dakotaraptor, Austroraptor, and Achillobator, it fits into the mid-sized range.
Scientists currently lack direct evidence for this animal’s skin covering, but enough of its close relatives show evidence of feathers that we can be reasonably certain it had them too. Its size means it didn’t use them for flight, but they were anchored into the bones like modern flying birds, so they served a function that subjected them to physical stress. One current hypothesis posits they may have stabilized the animal while it used its famous killing claw for a death grip attack on its prey.
We have four very different representations of Deinonychus in the park. The display that hits farthest from the mark is also the oldest: the little guys menacing the stegosaurs raise more eyebrows among our guests than any other exhibit. These Deinonychus sculptures have some charm, but some of their features—posture, scales, outstretched arms with incorrect poses—run counter to people’s expectations. They’re not the most inaccurate creatures in the park, so guests’ reactions might be a little unfair; in fact, the Deinonychus attack scene on the other side of the river has at least as many problems, but they satisfy visitors’ imaginations enough that people express surprise when I point out those mistakes. The head mounted in the courtyard should be labeled “Velociraptor” for reasons described below. Finally, the skeleton carved into the side of the museum next to the T-rex represents the most scientifically accurate depiction of this dinosaur in the park. It’s based on John Ostrom’s original drawings of the first one discovered, so its head is only slightly off. Of course, it’s much easier to get just a skeleton right in paleontology.
Greg Paul did more to distort Deinonychus’s image than almost any other scientist. In his 1988 book Predatory Dinosaurs of the World, he reclassified Deinonychus as a Velociraptor based on his insistence that their heads shared the same distinctive concave snouts. The idea never caught on among scientists, and has since been disproven by new fossil discoveries, but Paul’s book captured the public’s imagination anyway. Michael Crichton used it in writing Jurassic Park—his Velociraptors are actually Deinonychus, but he liked the name “Velociraptor” better. Descriptions in the book likewise follow Paul’s model for the head. Our attack scene also takes inspiration from Paul’s mistake.
What’s the real difference between maniraptors and other small theropods? The main difference lies in the crescent moon-shaped bone of the wrist that gives maniraptors more flexibility with their hands. Dromaeosaurs—the raptor group that includes Deinonychus—also had the distinctive toe claws and bony rods in their tails that give this animal its name, which means “counterbalanced terror claw.” True raptors also lived during the late Jurassic through the Cretaceous (Deinonychus itself lived in the early Cretaceous along with Acrocanthosaurus and Tenontosaurus; Coelophysis and Dracoraptor both lived much earlier.