Most of my watchers by now will have seen my two illustrations for this new dromaeosaur, but I think the discovery is exciting enough to warrant its own journal entry as well!
Without further ado: meet Dakotaraptor, the first "giant" dromaeosaur from the Hell Creek formation.
I've been sitting on these illustrations for months and can't think of the last time I've been so excited to illustrate a new taxon. At 5.5 meters in length and with magnificently robust ulnar quill knobs, this is not only the first "giant" dromaeosaur from Hell Creek, but it is also the first dromaeosaur in this size range with indisputable evidence of feathers. And not just shaggy and sparse "protofeathers" as many skeptics purport in defense of the "half-arse" integument pattern (I'm sorry you hate that image, Tom, but no other infographic uses the term "half-arse"...).
No, Dakotaraptor had massive ulnar quill knobs, which meant that its arms likely supported thick, heavy feathers with a stiff central rachis. This confirms, once and for all, that feathers stage 3 and beyond existed on dromaeosaurs larger than Velociraptor and Zhenyuanlong. What was such a large dromaeosaur doing with feathers like this? There are several options which are not mutually exclusive: brooding eggs, aggressive mating and territorial displays, shielding young... but many of you will recall my particular fondness for Denver Fowler's 2011 paper on "raptor prey restraint", which posited a unique predatory role for robust wings on non-volant dromaeosaurs. These wings would have acted as stabilizers and balancers for a large animal as it struggled atop still-living prey, much as modern birds of prey do. Modern hawks and eagles have evolved particularly stout and powerful ankles for this purpose, which allow greater torque for the inner claw on each foot to dig into unruly prey. This inner claw is, certainly by no coincidence, by far the largest on most birds of prey.
The use of RPR by Dakotaraptor means it would have been especially appropriate when grappling similarly-sized prey, and Hell Creek has given us the perfect also-feathered match: Ornithomimus, a new feathered specimen of which has been described just days before.
There is much to be said on Dakotaraptor, from its possible synonymity with Acheroraptor to its ecological relationships with other Hell Creek carnivores, but it should come as no surprise that the role of feathers in its predatory ecology is what interests me most! I look forward to seeing what future analyses and potentially more material will bring.
As for my watchers, I have a request of all of you: I have not had the time to sift through the rapid influx of new illustrations of this exciting taxon, so please link to your favorites in the comments! (I have seen the Saurian version many times and am more interested in seeing others, mind you.)