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The Terrible Claw
By EWilloughby   |   Watch
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Published: August 5, 2014
© 2014 - 2019 EWilloughby
Diagnostic anatomical reconstruction of Deinonychus antirrhopus, intended loosely for Wikipedia but also as an experimental piece to show pretty much exactly how I believe this animal looked in life.

This was largely inspired by an interesting Facebook discussion with paleoartist Julius Csotonyi about arm-folding in paravian dinosaurs. It occurred to me that people seldom reconstruct paravians, particularly dromaeosaurs, with their arms folded in a reasonable and accurate way. Julius made the fair point that these animals probably didn't carry their arms out in front of the body, as is so often depicted (in skeletals and otherwise — it makes sense in skeletals, to adequately show the hand and arm anatomy), because such an awkward orientation would leave the hand and arm feathers open to damage and breakage. But they also can't fold them tightly against the breast or back like birds do, because they lack the mobility to do so.

So how did Deinonychus normally carry its arms? Senter's 2006 paper on forelimb function in Deinonychus and Bambiraptor shows that the humerus couldn't rotate much past the horizontal with respect to the scapula. In addition, Sullivan et al. 2010 — winningly translated to layman coherency by Matt Martyniuk — shows that wrist mobility in many paravians is much less than you might expect, given their similarity to birds. The wrist of Deinonychus antirrhopus specifically would not have allowed it to bend its hands even 90° with respect to the arm!

Given these limitations, most of the flexion would have to occur at the elbow, but a fully flexed elbow would mean that the hands would be hanging below the body, not held sleek and secure alongside the body. The arm orientation in my illustration above is based on what I think is probably the perfect configuration for carrying the arms: a fully-flexed shoulder, a fully-flexed wrist, and a nearly fully-extended elbow. A few other people have drawn their dromaeosaurs with the same arm configuration, like Smnt2000 and pilsator, so kudos to them. 

Illustration based on the papers linked above as well as ScottHartman's beautiful skeletal. Gouache on 12" x 20" hot-pressed illustration board. 
Image size
1600x692px 242.17 KB
IMAGE DETAILS
Software
Adobe Photoshop CS4 Macintosh
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Comments (101)
WinterWantsMoon's avatar
love this art. prefer this over JP raptors anyday!
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WestSeax's avatar
I'm rather skeptical of the idea that holding the arm out in front of the animal would lead the arms and feathers being damaged and broken. If you've ever seen chicken run they hold out their wings for balance and even flap them to get a boost. Parrots will often also hold their wings out while climbing, ready to flap in case they lose their balance. I've owned lovebirds and they often beat their feathers off the bars of the cage and their perches while climbing or hopping but it doesn't seem to bother them. I personally tend to imagine that these critters held them out below them, maybe spread a little (to the extent they could spread them), for balance and ready to snatch up prey.
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seemycriitersss's avatar
So why are chickens the only birds people like to compared dinosaurs to?
would that be like comparing a house cat to a saber tooth cat?
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acepredator's avatar
It would be like comparing a mouse to a Sabretooth.
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Batterymaster's avatar
Batterymaster|Student General Artist
Because its an excuse for BANDits to ridicule feathered dinosaurs, that's why.
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WinterWantsMoon's avatar
yes. there is no need for the hate feathered dinosaurs get. It's like everyone wants the Jurassic park raptors back and dismisses almost fact on how the animals looked like. 
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william023's avatar
I hated seeing raptors running about with arms out in front, it always looked silly because it would slow them down and yes, in enclosed spaces, it'd damage their wings, but it also just made them look awkward because they weren't streamlined, I prefer this sleeker stance. I mean, they obviously outstretched their wings when balancing on bigger prey, fighting each other, maybe when hugging(don't laugh, some birds really do wrap wings around each other), for warming eggs and chicks, or just threatening opponents. But the world needs more streamlined dromeosaurs.
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zappyzor's avatar
zappyzor|Student Digital Artist
I love this picture
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IK16's avatar
I agree.
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ViktorArnason's avatar
hi TREY sent me
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MilenaJure's avatar
is it Deinonychus? i love it
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chinmoy808's avatar
chinmoy808|Hobbyist Traditional Artist
it is
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Creature218's avatar
I just got an idea for Jurassic park 5  they find more complete dinosaur dna and have the feathered dinosaurs fight the non feathered ones, P.S. most amazing dinosaur art I have ever seen
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acepredator's avatar
I've been thinking that for a long time...and an accurate Spinosaurus drowns the JP version.
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WinterWantsMoon's avatar
funny, epic, but sad. 
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JustaRandomGourgeist's avatar
JustaRandomGourgeist|Hobbyist Digital Artist
That would be both epic and funny to see
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Imperator-201's avatar
Yessss, that's my idea exactly! And I say this because in the film Jurassic World a character says that the dinosaurs would look different if they had 100% pure DNA.
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BaryMiner's avatar
BaryMiner|Student Traditional Artist
I applaud you for having the most accurate raptors I have EVER seen! Clap 
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grisador's avatar
Does it capable of using its hand/claws ? :O
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EWilloughby's avatar
EWilloughby|Professional General Artist
There is surprisingly little evidence to suggest that dromaeosaurs, despite the robust hand-claws, were using their hands in predation at all. Some researchers have suggested that the main function of handclaws may have been to support a partially arboreal lifestyle, at least in juveniles. The function of handclaws in dromaeosaurs is still an open question, as far as I'm concerned. 

That said, there is no reason to assume that large hand and arm feathers would preclude mobility and grasping ability in dromaeosaur hands. The Senter paper linked in the description covered this quite nicely, and here's my take on it.
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DovahsaurPaleoKnight's avatar
That is pretty interesting, but do we have any evidence to how, or if, the primaries would prevent much movement from their middle fingers?
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grisador's avatar
Thanks a Lot for the answer & the Link !

I see. İts still an unclear subject; But the grasping\catching ability seems very Possible
Its also possible to Raptor's use their proto-wings and claws at their infancy
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