Dakotaraptor

Dakotaraptor is a genus of large maniraptoriform theropod dinosaur that inhabited western North America during the very end of the Late Cretaceous period. Its remains have been discovered in the Maastrichtian-aged Hell Creek Formation, placing it among potentially the last surviving dromaeosaurids. Despite its classification being subject to ongoing research and debate, Dakotaraptor is notable for its impressive size, estimated to reach lengths of up to 6 meters and weigh as much as 350 kilograms, making it one of the largest known dromaeosaurids.

Discovery and Naming

The fossils of Dakotaraptor were first discovered in 2005 by paleontologist Robert DePalma in a fluvial bonebed in Harding County, South Dakota. The genus and type species, Dakotaraptor steini, were formally named and described in 2015 by a team including DePalma, David A. Burnham, Larry Dean Martin, Peter Lars Larson, and Robert Thomas Bakker. The genus name, "Dakotaraptor," signifies a "thief from Dakota," referencing its discovery location and the Latin word for plunderer. The species epithet, "steini," honors paleontologist Walter W. Stein.

Physical Characteristics

Dakotaraptor was characterized by its substantial size, approaching that of Utahraptor, another large dromaeosaurid. However, its proportions more closely resembled those of smaller dromaeosaurids like Deinonychus. A significant distinguishing feature is the presence of prominent quill knobs, or ulnar papillae, along the lower edge of its ulna. These bumps are strong indicators of large, pennaceous feathers attached to the wing, confirming that Dakotaraptor possessed substantial plumage despite being flightless. Its legs were lightly built with elongated elements, particularly the tibia, suggesting high running capabilities suited for pursuit predation.

Paleobiology and Paleoecology

Dakotaraptor was a carnivore, equipped with a robust, sickle-shaped claw on its second toe, a characteristic weapon for subduing prey. The third foot claw was notably smaller and less functional in attack. Fossil material suggests the presence of two morphs, possibly indicating sexual dimorphism. Despite being too heavy for flight, its wings likely served other functions such as shielding eggs, display, intimidation, or maintaining balance while pinning down prey. In the Hell Creek Formation ecosystem, Dakotaraptor occupied a niche as a medium-sized predator, intermediate in size between smaller deinonychosaurs and the giant Tyrannosaurus. It likely preyed on herbivores and may have competed with juvenile tyrannosaurs.