Largest feather-winged raptor

The largest species of dinosaurian raptor known to have possessed feathers on its wings is Dakotaraptor steini, which was formally described and named in October 2015, and measured 5–6 m long. The existence of feathers on its wings (i.e., its forelimbs) was confirmed by the presence of a row of very prominent bumps along a ridge on the lower edge of the fore-arm bone known as the ulna. These bumps are thus referred to as ulnar papillae, or quill knobs, and are also present in modern-day birds, functioning as bases for the reinforced attachment of the wing feathers (remiges). As its name indicates, this species was found in South Dakota, USA. It lived there during the late Cretaceous Period, approximately 66 million years ago.

Dakotaraptor steini was first discovered in 2005 in the Hell Creek Formation of South Dakota, which is where Tyrannosaurus rex remains have also been found, and of the same age as those of this new species. Consequently, these two species would have co-existed here. Moreover, Dakotaraptor was one of the very last-surviving raptors, and at 5–6 m long it was also one of the largest.