Need help on raptor hands!

[acro-man]

Hi guys,
I am about to modify the Rebor Windhunter Utahraptor regarding its somewhat uneasy pose.
Before that, I want to get some knowledge about raptor hands.
Can somebody help me with the following questions?
Would very much appreciate his/her kindness.




1. What are the hands used for?
From Scott Hartman's raptor skeletons, they don't look very strong.
The angle between the forearm and the digits (the way the wrist is joint) doesn't look like they are evolved for 'grabbing'.
So how to use these hands?

2. Can the wrist turn flexibly?
Just like this?

Wikipedia says they "were similar in construction and flexibility to the wing bones of modern birds"
If so, when it's running, where will the hands be posed?

3. Where do the feathers arise?
Do the feathers arise from arms and extend long enough to cover the 2 digits?
Or they arise from the 2 digits themselves?

That's for now.
Thank you

[Halichoeres]

I'm not an expert on theropods, so take everything I say with some skepticism.

I think the wrists do flex in the plane that you describe in your picture, although I don't know the full extent of their flexibility. I think that the wings, while running, would be held alongside the body in the same way as a quail. I imagine that the hands would be brought forward for prey handling. The ability of hoatzins to climb with their claws suggests that even relatively spindly hands can have enough strength to be useful.

Besides feathers arising from the arm itself, there would be primaries originating on the second digit. I'm not sure about the third, but even if there were feathers there they would be overlain by the primaries. I also am not sure about the first digit, somebody else here probably knows more about that. It's definitely feathered in modern birds, but it's also substantially reduced relative to Utahraptor.

Hope that helps. I expect you'll get more clarity from people more knowledgeable than I am about theropods.

[stargatedalek]

The hands existed primarily if not nearly solely to support the wings. I imagine they could have been used in preening or in self-defense if the animal was desperate, but using them to attack would risk damaging the wings (and even the fingers themselves).

The wrist was not particularly mobile. Senter argued that despite their gracile nature the digits could have been used to hold small objects without obstructing the wings, this however was purposed before feathering each individual finger became the expectation. Regardless the diagram of wrist movement may still prove useful.


Here are some good diagrams of wings, mind you most are missing the coating of feathers on each individual finger (note; not large feathers, just coating feathers like down). The first is actually a dated reconstruction but given Utahraptor's size a more minimal wing could be plausible.

I imagine that the hands would be brought forward for prey handling. The ability of hoatzins to climb with their claws suggests that even relatively spindly hands can have enough strength to be useful.

Hoatzin chicks are practically naked when they still retain the use of their claws, and aside from the actual presence of a "nail" they are basically what's seen in every other flying bird but stronger. Hoatzin chicks are equally (if not more) reliant on swimming as they are flying and the limbs and digits are very bulky relative to other birds let alone dromaeosaurs (dromaeosaurs may have larger fingers but bird fingers are encased in "Hulk-esque" amounts of flesh). They don't gain their dexterity from their claws alone, but rather from their lack of shafted feathers to become damaged and from their thick and powerful limbs, the claws are just there to dig into the bark.

[DinoLord]

The wrists likely could not fold back to the extent seen in birds.

[Halichoeres]

There you go, some input from theropod people!

[acro-man]

people, that really helps a lot!
thank you all so much.
with all the supporting info, I come up with 3 proposals.
ORIGINAL


MOD 1 - folded hands


MOD 2 - right-angle hands


MOD 3 - reversed hands


I personally like the third most.
I know it's far from being accurate, but this is the best I can do.