Dromaeosauridae
Among the dinosaurs, the Dromaeosaurids or Dromaeosauridae ("running lizards") were fast and agile dominant carnivores throughout the Cretaceous period. In popular usage they often called "raptors" after the Velociraptors made famous by the film Jurassic Park. Dromaeosauridae have been found in North America, Europe, North Africa, Japan, China, Mongolia and Argentina. They were a very successful group in the Cretaceous, existing for over 60 million years, up until the Cretaceous-Tertiary extinction event.
Relationship with birds
Dromaeosaurids are theropods, and are a sister group to modern birds. Discussion about the relationship between birds and dinosaurs has narrowed to whether bird ancestors lie within Dromaeosauridae or not. Dromaeosauridae is a subgroup of Deinonychosauria, and includes such animals as Deinonychus, Dromaeosaurus, Velociraptor, Saurornitholestes, and Utahraptor.
Recently described dromaeosaurs, such as Microraptor gui, Cryptovolans and the Chinese Sinornithosaurus had modern pennaceous feathers and fully formed remiges or "flight feathers", leading to the question of whether these animals were capable of powered flight.
See also: Feathered dinosaurs
Characteristics
The characteristics of the Dromaeosauridae are distinctive. Unlike their close relatives, such as Troodon, dromaeosaurids were muscular animals. Long fleshy tails held out behind could help them swing quickly to change direction. They were lightly built, agile, bipedal hunters, with large eyes. They also had the biggest brains for their body weight among all dinosaurs (see encephalization quotient), which indicates that they were among the most intelligent dinosaurs, their intelligence perhaps approaching that of modern-day birds of comparable sizes.
There is evidence that some dromaeosaurids hunted in packs: Deinonychus fossils have been uncovered in small groups that seem to have been killed while attacking Tenontosaurus tilletti, a larger ornithischian dinosaur. Not all paleontologists find the evidence conclusive, however.
The enlarged "killer claw" possessed by some dromaeosaurs (Deinonychus means "terrible claw") was a raking weapon that could open a deep disembowelling gash. Then the agile predator could withdraw and wait for a victim to weaken from bleeding.
In fiction
Velociraptor made a memorably chilling villain in the movie Jurassic Park, although it was enlarged far beyond its actual size. While the movie was in production, the discovery of Utahraptor confirmed that such giant Dromaeosaurids did in fact exist.