Dromaeosaurus was a genus of theropod dinosaur which lived during the Late Cretaceous period (middle late Campanian), sometime between 76.5 and 74.8 million years ago, in the western United States and Alberta, Canada. The name means 'running lizard' and is derived from the Greek dromeus (δρομευς) meaning 'runner' and sauros (σαυρος) meaning 'lizard'. though most experts nowadays conclude that dromaeosaurs were comparatively robust and likely short distance runners.
Discovery and naming[]

1922 diagram of the holotype skull
Despite receiving widespread attention in popular books on dinosaurs, and the usage of a complete mounted skeleton cast in museums throughout the world, Dromaeosaurus is surprisingly poorly known from actual fossils. The preparation of the popular cast by the Tyrrell Museum was only made possible by knowledge gained from other dromaeosaurids that have been discovered more recently.
The first known Dromaeosaurus remains were discovered by paleontologist Barnum Brown during a 1914 expedition to Red Deer River on behalf of the American Museum of Natural History.[1] The area where these bones were collected is now part of Dinosaur Provincial Park in Alberta, Canada.[2] The find consisted of a partial skull 24 cm (9.4 in) in length, and some foot bones.[1][2] Several other skull fragments, and about 30 isolated teeth, are known from subsequent discoveries in Alberta and Montana.[2]
Several species of Dromaeosaurus have been described, but Dromaeosaurus albertensis is the most complete specimen.[2] Additionally, it is apparent that this genus is even rarer than other small theropods, although it was one of the first small theropods described based on reasonably good cranial material.[2]
Matthew and Brown originally placed Dromaeosaurus within "Deinodontidae" (now known as Tyrannosauridae), based on some similarities in the general proportions of the skull.[1] In 1969, John H. Ostrom recognized that Dromaeosaurus shared many features with Velociraptor and the newly-discovered Deinonychus, and assigned these forms to a new family: Dromaeosauridae.[3] Since then, many new relatives of Dromaeosaurus have been found.
Description[]

Artistic restoration of D. albertensis
Dromaeosaurus was a small carnivore, about 2 m (6 feet 7 inches) in length and 15 kilograms (33 lbs) in weight. Its mouth was full of sharp teeth, and it had a sharp "sickle claw" on each foot. It lived during the Campanian stage of the Late Cretaceous, however, some fragmentary remains such as teeth which may belong to this genus have been found from the late Maastrichtian age Lance and Hell Creek Formations, dating to 66.038 million years ago. Dromaeosaurus had a relatively robust skull with a deep snout. Its teeth were rather large and it had only nine of them in the maxilla. In Dromaeosaurus albertensis, a vein at the back of the head, the vena capitis dorsalis, drains the front neck muscles through two long canals running to the posterior surface of the brain.
Although only a few bones are known from the hindlimb, they indicate that Dromaeosaurus was a powerfully built animal. The presence of feathers in closely related animals makes it extremely likely that it was feathered as well.
Dromaeosaurus had remarkably large eyes and excellent vision. It also probably had a good sense of smell and hearing. Its neck was curved flexible and its jaws were solidly built. The tail was flexible at the base but sheathed in a lattice of bony rods; this allowed it to be carried in a sharply upturned position.
Classification[]

D. albertensis skull cast exhibited the Geological museum, Copenhagen, Denmark
Matthew and Brown originally placed Dromaeosaurus to its own subfamily, the Dromaeosaurinae, within the "Deinodontidae" (now known as Tyrannosauridae) based on some similarities in the general proportions of the skull.[1] In 1969, John H. Ostrom recognized that Dromaeosaurus shared many features with Velociraptor and the newly discovered Deinonychus, and assigned these forms to a new family: Dromaeosauridae.[3] Since then, many new relatives of Dromaeosaurus have been found.
The exact relationships of Dromaeosaurus are somewhat unclear. Although its rugged build gives it a primitive appearance, it was actually a very specialized animal.[4] In an analysis of the clade Dromaeosaurinae, species such as Utahraptor, Achillobator and Yurgovuchia have been recovered.[5] The genus Dakotaraptor has been classified as the sister taxon to Dromaeosaurus,[6] but more recent analysis do not recover such a close relationship.
Below is a cladogram by Senter et al. in 2012. Dromaeosaurus is recovered as the sister taxon to Yurgovuchia, Utahraptor and Achillobator.[5]
Eudromaeosauria |
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Size of Dromaeosaurus (4) compared with other dromaeosaurs
The cladogram below follows a 2015 analysis by paleontologists Robert DePalma, David Burnham, Larry Martin, Peter Larson, and Robert Bakker, using updated data from the Theropod Working Group. In this analysis, Dromaeosaurus is classified as the sister taxon of Dakotaraptor.[6]
Eudromaeosauria |
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Paleobiology[]
Dromaeosaurus differs from most of its relatives in having a short, massive skull, a deep mandible, and robust teeth. The teeth tend to be more heavily worn than those of its relative Saurornitholestes, suggesting that its jaws were used for crushing and tearing rather than simply slicing through flesh. Therrien et al. (2005) estimated that Dromaeosaurus had a bite nearly three times as powerful as that of Velociraptor.[7]
It is possible that Dromaeosaurus was more of a scavenger than other small theropods, or it may be that Dromaeosaurus relied more heavily on its jaws to dispatch its prey. It was probably better suited to tackling large prey than the more lightly built Saurornitholestes.
Relationships[]

Dromaeosaurus foot
The relationships of Dromaeosaurus are unclear. Although its rugged build gives it a primitive appearance, it was actually a very specialized animal.[4] It is usually given its own subfamily, the Dromaeosaurinae; this group is thought to include Utahraptor, Achillobator, Adasaurus and perhaps Deinonychus.
However, the relationships of dromaeosaurs are still in a state of flux. "Dromaeosaurus Morphotype A" is the designation given to a series of unusual, ridged dromaeosaur teeth from Alberta. These teeth probably do not belong to Dromaeosaurus, although it is unclear from what animal they do come.
JPInstitute.com Description[]
Dromaeosaurus was the original raptor. It was a small, vicious hunter that had a mouth full of serrated, razor-sharp teeth and a sharp, hooked claw on each foot that it used to clamp down on its victims.
When first discovered, Dromaeosaurus was hard to classify. It had such large foot bones that it was thought to be a much larger dinosaur. It had a large brain for its size, large eyes and grasping hands. Because of this, scientists thought that it was more than twice its actual size. It wasn't until almost 50 years after the discovery of the type specimen that it was formally classified into its own family. All the other raptor dinosaurs, such as Deinonychus and Velociraptor, are members of the dromaeosaur family.
Links[]
Further reading[]
- Dixon, Dougal (2006). The Illustrated Encyclopedia of Dinosaurs (Lorenz Books): 200-201.
- Colbert, E. and D. A. Russell (1969). The small Cretaceous dinosaur Dromaeosaurus. American Museum Novitates 2380: 1-49.
- Currie, P. J., K. J. Rigby, et al. (1990). Theropod teeth from the Judith River Formation of southern Alberta, Canada. Dinosaur Systematics: Perspectives and Approaches. P. J. Currie and K. Carpenter. Cambridge, Cambridge University Press: 107-125.