Dakotaraptor

Chapter • Meet the dinosaur

Overview

Dakotaraptor was one of the largest predatory dinosaurs in the family Dromaeosauridae, the group that also contains Velociraptor and Deinonychus. It reached roughly 4.4–6 metres in length and is estimated to have weighed 220–350 kilograms, standing about 1.5–1.8 metres tall at the hip. Everything about its skeleton suggests speed: long, slender hind limbs, a long stiffened tail held horizontally as a balancing rod, and a greatly enlarged, sickle-shaped claw on the second toe of each foot, held clear of the ground while walking. The ulna preserves clear quill knobs — the attachment points for large wing feathers — giving direct fossil evidence that the arms carried long, stiff pennaceous feathers. Dakotaraptor could not fly, but was almost certainly feathered over most of its body. Its proportions point to an active, fleet-footed animal. The elongated lower leg bones set Dakotaraptor apart from short-limbed relatives such as Utahraptor and suggest it could run quickly, perhaps in the region of 40–45 km/h, though all speed figures for extinct dinosaurs are calculations rather than measurements. The arm feathers served no aerodynamic purpose in an animal this heavy; they were more plausibly used for display, for shielding eggs and young, or for stability while pinning struggling prey. The famous toe claw most likely worked as a gripping and puncturing weapon rather than a slashing blade. Dakotaraptor was a carnivore sharing its landscape with Tyrannosaurus rex, Triceratops and the duck-billed Edmontosaurus. At its size it probably occupied an ecological space between the small carnivores and the adult tyrannosaurs, taking juvenile and mid-sized herbivores, smaller dinosaurs, turtles, lizards and mammals, and no doubt scavenging carcasses when the opportunity arose. The species was named in 2015 by Robert DePalma and colleagues, based on material from the Hell Creek Formation of South Dakota, USA — the name means roughly "raider from Dakota". The holotype is not a single articulated skeleton but a set of bones from one quarry, and researchers have debated whether every element truly belongs to the same animal. One bone originally identified as a furcula (wishbone) was shown shortly after publication to be the entoplastron of a soft-shelled turtle. Dakotaraptor therefore remains an important but partly contested dinosaur, and new specimens are needed to settle the details of its anatomy.

Chapter • Where it lived

Habitat

Dakotaraptor is known only from the Hell Creek Formation of South Dakota, USA, deposited during the Maastrichtian — the final age of the Cretaceous — about 67 to 66 million years ago. The setting was a warm, humid coastal plain beside the retreating Western Interior Seaway, crossed by braided and meandering rivers, with floodplains, swampy conifer and flowering-plant forests and more open fern-covered ground. Tyrannosaurus, Triceratops, Edmontosaurus, Ankylosaurus, Pachycephalosaurus and Thescelosaurus lived here alongside turtles, crocodilians, early birds and small mammals. The type material comes from a single quarry in Harding County, South Dakota.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy