Atrociraptor (meaning "savage robber") is a genus of dromaeosaurid theropod dinosaur from the Late Cretaceous (Maastrichtian stage) of Alberta, Canada.
Holotype skull at the Royal Tyrrell Museum
The type (and only) specimen of Atrociraptor, holotype RTMP 95.166.1, was discovered by Wayne Marshall in 1995, in layers of the Horseshoe Canyon Formation also containing an Albertosaurus bonebed, near Drumheller. This bonebed is located at the top of Unit 4 of the Horseshoe Canyon Formation, which dates to about 68.5 million years ago. The only known specimen consists of parts of the upper and lower jaws — both premaxillae, a right maxilla, both dentaries — teeth and numerous small fragments. The skull appears to have been unusually short and tall. The teeth are relatively straight, but they emerge from the tooth sockets at an angle to the jaw line, resulting in a strongly raked row of teeth. A number of isolated teeth (previously referred to Saurornitholestes) have also been recovered from the Horseshoe Canyon Formation; they can be recognized by their unusually large serrations.
Discovery[]
Skeletal diagram showing the position of the holotype jaw remains
The first Atrociraptor remains were discovered in 1995 when a local man named Wayne Marshall unearthed a series of teeth and jaw parts from the Horseshoe Canyon Formation in Alberta, Canada. However, it wasn't formally described until 2004, when paleontologists Phillip J. Currie and David Varricchio gave it the name Atrociraptor. To this day, the 1995 finding is the only known Atrociraptor specimen.
Assigned tooth
Like Velociraptor, Atrociraptor was one of the smaller members of its family, reaching around 2 m (6 ft) long and weighing 15 kg (33 lb); significantly smaller than its portrayal in the Jurassic World canon, which measures 3.9 m (12.8 ft) long and weighs around 226 kg (500 lb).
Description[]
Size compared to a human
In 2004 Philip J. Currie and David Varricchio named and described the type species of Atrociraptor: Atrociraptor marshalli. The generic name is derived from the Latin atrox, "savage", and raptor, "seizer". The specific name honours Marshall.
In 2010 Gregory S. Paul estimated its length at two metres, its weight at fifteen kilogrammes. Atrociraptor differs from Bambiraptor and other velociraptorines in its more isodont dentition — the teeth have different sizes but the same form — and short deep snout. A skull opening, the maxillary fenestra, is relatively large and positioned right above another opening, the promaxillary fenestra, a condition not known from other species.
Atrociraptor was by its describers assigned to the Velociraptorinae within a larger Dromaeosauridae. However, in 2009 Currie published a cladistic analysis showing Atrociraptor to be a member of the Saurornitholestinae. Atrociraptor was named by Phillip J. Currie and David Varricchio in 2004, deriving from Latin "atrox", "savage", and "raptor", "seizer". The species epithet honours Marshall.
Classification[]
Reconstructed skeleton of the related Bambiraptor, a fellow member of Saurornitholestinae
Atrociraptor was by its describers assigned to the Velociraptorinae within a larger Dromaeosauridae. However, in 2009 Currie published a cladistic analysis showing Atrociraptor to be a member of the Saurornitholestinae. A 2022 study and analysis further vindicates this position and classifies Atrociraptor as a derived saurornitholestine, along with Acheroraptor.
The cladogram below shows the position of Atrociraptor within Dromaeosauridae according to the 2022 analysis by Jasinski and colleagues:
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Paleoecology[]
Hypothetical restoration of various dinosaurs known from the Horsethief Member of the Horseshoe Canyon Formation, where the first Atrociraptor specimen was found
Atrociraptor lived along the floodplains and swamps in the Horseshoe Canyon Formation of Alberta, Canada during the Late Cretaceous period around 83–66 million years ago. It lived alongside dinosaurs such as the Albertosaurus, Edmontosaurus, Pachyrhinosaurus, and Struthiomimus.
Appearance in other media[]
Jurassic Park[]
- A pack of 4 Atrociraptors appears in Jurassic World Dominion. Like with other dromaeosaurids in the franchise, they are over-sized, featherless, and have pronated wrists. Their design is very similar to Jurassic World's Velociraptor, but with a much boxier head and longer legs along with a very pale coloration. This pack of 4 was trained to kill at the point of a laser and would stop at nothing until their target was dead.
- Atrociraptor is also included in the Dominion Malta Expansion paid DLC for Jurassic World Evolution 2. Their model, behavior, and sounds are heavily based on Jurassic World Dominion.
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