Wing Feathers

[Seijun]

Many theropod dinos are restored nowadays with feathers. Often they are given very complex and very bird-like flight feathers on their arms, particularly raptors, even when the species could not fly and did not evolve from anything that could fly. I admit the more bird-like wings LOOK very cool, but realistically was it very likely? Would flight feathers, or feathers resembling modern flight feathers, have had any reason to evolve in a species that could not fly or even glide? Was it more likely that the "wings" of most feathered theropods would have looked more like the wings of an ostrich or emu?

[Jetoar]

It is a good question Seijun. I think that no avian theropods have ornamental feathers in his arms likes as Concavenator but not kind of wings. It is posible that big and gigants Theropods have feathers likes as emus  or not depend their habitats and raptors have featheres in their arms like as true wings, from my point of view  .

[Dinoguy2]

Given the fact that bird-like wings evolved in things like ornithomimids and oviraptorids long before anything that could conceivably fly or glide, they must have evolved for reasons other than flight at first, such as display or covering nests/eggs. Caudipteryx, for example, had tiny wings and was way too large to fly, glide, or even climb, yet it had basically bird-like wing feathers. It probably evolved these for display.

Also, there are other functional reasons for large predators like Deinonychus to keep or evolve normal wings:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028964
(Flapping the stabilize themselves on top of struggling prey, also known as the "ripper" hypothesis). Emu-like wing feathers wouldn't be as effective for this. We know for a fact Velociraptor had large wing feathers, but you're right that we don't know if they were vaned like those of flying birds or loose and ostrich-like.

Interestingly, in juvenile Sinornithosaurus (Dave specimen) the wing feathers are vaned and bird-like, but in adults they appear to be loose and emu-like (unless they degraded after death). It's theoretically possible that some dromaeosaurs could fly as juveniles and became flightless as adults, and the wing feathers changed accordingly. And anyway...

the species could not fly and did not evolve from anything that could fly.

That's very debatable. It's entirely possible that dromies evolved from flying ancestors. At least two of the most primitive known dromaeosaurs (Rahonavis and micro raptor) could probably fly at least a little. Not that this has much bearing on the wings of advanced dromies--emus also evolved from flying ancestors, but they don't have well-developed wing feathers. Presence of those requires a functional reason to keep them.

[Seijun]

Thanks for the info. In the case of ornithomimids, oviraptorids, velociraptor, etc, do we actually have fossil impressions of the wing feathers, or just evidence that feathers existed, like having quill knobs?

[Jetoar]

From my point of view, This collecta T-rex is a combination of Raul Martín and Jurassic Park T-Rex  .

[ZoPteryx]

Thanks for the info. In the case of ornithomimids, oviraptorids, velociraptor, etc, do we actually have fossil impressions of the wing feathers, or just evidence that feathers existed, like having quill knobs?

There are "wing feather" impressions for ornithomimids and oviraptorids.  Velociraptor is known to have quill knobs which are nearly identical to those of known winged raptors (like Sinornithosaurus), so it probably had a very similar feather arrangement.  Seeing as it's now been proven that sandstone can hold soft tissue impressions, I suspect lots more dinos will soon be getting their wings.