Atrociraptor roamed the Earth during the final stages of the Age of Dinosaurs. This creature was a dromaeosaurid, a group of agile, carnivorous dinosaurs often referred to as “raptors.” Measuring approximately 1.8 to 2 meters (about 6 to 6.6 feet) in length and weighing around 15 kilograms (33 pounds), Atrociraptor was a relatively small predator. Its name, meaning “savage robber” or “savage thief,” hints at its predatory nature. Its dental features included teeth that were nearly uniform in size and angled backward in its unusually deep snout.
Its Geographic Home
Atrociraptor remains have been found exclusively in Alberta, Canada, within the Horseshoe Canyon Formation. The single known specimen was unearthed in 1995 by fossil collector Wayne Marshall, approximately 5 kilometers west of the Royal Tyrrell Museum of Palaeontology. This limited fossil evidence means all current understanding of Atrociraptor’s habitat stems from this singular find.
The Time of Its Reign
Atrociraptor lived during the Late Cretaceous period, specifically within the Maastrichtian age. This geological epoch spanned from about 72.2 to 66 million years ago, representing the very end of the Mesozoic Era. The particular bonebed where the Atrociraptor holotype was found dates to approximately 68.5 million years ago. This period was just prior to the major extinction event that marked the end of the Cretaceous.
The Ancient Environment
During the Late Cretaceous, the area that is now Alberta, Canada, was part of a large landmass called Laramidia, which was separated from eastern North America by the Western Interior Seaway. Atrociraptor’s world was characterized by a warm, subtropical climate. The landscape consisted of humid coastal plains, crisscrossed by numerous rivers and deltas, and featured extensive coal swamps.
Lush forests dominated the environment, with abundant conifer trees and flowering plants. This setting supported a wide array of other dinosaur species that shared the habitat with Atrociraptor. These included large herbivores like the duck-billed Edmontosaurus and the horned Pachyrhinosaurus, as well as armored Edmontonia. Larger predators, such as the tyrannosaurid Albertosaurus, also coexisted in this ancient Canadian landscape.
How We Know
Our understanding of Atrociraptor’s existence and environment comes from the discovery of its holotype specimen, designated RTMP 95.166.1. This fossil, a partial skull including upper and lower jaw bones and associated teeth, was formally described as the new genus and species, Atrociraptor marshalli, by paleontologists Philip J. Currie and David Varricchio in 2004.
Scientists reconstruct ancient environments by analyzing the geological context of fossil finds. The type of rock formations, such as the mudstones, sandstones, and coal seams of the Horseshoe Canyon Formation, provide clues about past depositional settings like floodplains and swamps. Additionally, fossilized plant remains and other animal fossils found alongside the dinosaur help to paint a picture of the ecosystem and climate.