Would dromaeosaurs (and other non-avian maniraptorans) have walked like birds?

[CarnotaurusKing]

When birds walk, all of the movement is at or below the knee, and the thigh barely moves (if at all). This YouTube video shows what I mean:

Would dromaeosaurs have walked the same way? The question also applies for other maniraptorans, and ornithomimosaurs. Most (if not all) of the walk cycles I have seen for dromaeosaurs show them walking like other theropods or like humans, with the leg moving at the hip. Since they are otherwise very similar to birds, would they be the same in this regard as well? Or is the gait of birds a more derived trait, and maybe an adaptation for flight?

[Halichoeres]

I don't think it's really either or. This paper shows guinea fowl move all of the limb elements, but that walking is comparatively stiff-legged. By contrast, running engages the hip a lot more. You'll see in birds that walk a lot, like ratites, as well as in most theropods, that the ilium is long, which means a lot of muscle attachments for muscles to swing the leg from the hip.

https://www.researchgate.net/figure/Walking-and-running-gaits-in-birds-A-Schematic-illustration-of-a-walking-and-running_fig1_325292394

[stargatedalek]

You can't really see the upper leg in any of these animals since it's within the feathers anyway, only a vague outline. So the movement looks far more diminished than it necessarily is.


The walkcycle as demonstrated here (there is even a JP styled raptor shown on screen at one point) is primarily due to digitrade movement and theropod hips, so this is attributable to most theropods.

[Newt]

My understanding is that the main reason birds walk from the knee, so to speak, is to keep the legs beneath the center of balance. The hip joint is well behind the center of balance in birds due to (1) the lack of a proper tail and (2) the concentration of muscle mass in the pectoral region, so birds essentially use the knee as a surrogate hip. These balance issues do not apply to flightless non-avian theropods, so they would probably not walk the same way.

[HD-man]

Reminds me of Willoughby's "Deinonychus Walk Cycle": https://www.deviantart.com/ewilloughby/art/Deinonychus-Walk-Cycle-432160150

[DerbesSchuhwerk]

Remembers me on the experiment on chickens, where the center of mass is shifted, due to a "fake tail", a stick attatched to the chicken, which results in a very dinosaurian walk.



https://www.theguardian.com/science/lost-worlds/2014/mar/20/did-losing-their-tails-make-birds-cock-o-the-walk

[Faelrin]

D @DerbesSchuhwerk Ah yeah I remember coming across this a while back. Such a fascinating study. I wonder if they would be able to replicate that chicken walk study with a larger bird like an ostrich and emu, and what the results of it would be?

I'm also wondering if non-avian dinosaurs were capable (or honestly if even all extant birds as well) or are able to keep their head still while their body moves and/or that other swift jerky head movements birds appear to have (which I vaguely recall the JP novel raptors being described as doing)?

An older video, but this shows the kind of thing I mean:

[CarnotaurusKing]

Thank you all for the answers! So, like @Newt said, the knees in chickens are like a surrogate hip, and when the centre of balance is shifted further back (like in D @DerbesSchuhwerk 's video), the legs swing much more at the hip. That makes sense. I'm only a casual when it comes to palaeontology, so I'm sorry if the question is a bit amateurish.

@Faelrin also brought up a good question about head movement, I am interested to see what people think of that.

[Halichoeres]

I'd say based on this (https://www.cell.com/current-biology/pdf/S0960-9822(09)00668-X.pdf) that something like a dromaeosaur could plausibly have done some head stabilization, but maybe not to the extent of birds. Birds have enormous eyes relative to their skulls, and they aren't spherical, which means that, although they have extrinsic ocular muscles, the amount of rotation they can manage in the orbit is limited compared to a mammal. Bird head stabilization is at least in part about keeping the field of view steady, and most larger dinosaurs wouldn't have needed that because there was room in the orbit to move the eye itself. But something like a troodontid or a dromaeosaur, you might be looking at an eyeball:orbit size ratio where fixity would be useful.

[Faelrin]

@Halichoeres Thank you for sharing that article, and your thoughts on the matter. Always wondered how that was possible. 

Come to think of it something like that would also be useful in RPR would it not?

[Halichoeres]

Forgive me, I'm not sure what RPR stands for.

[Gwangi]

Forgive me, I'm not sure what RPR stands for.

Raptor Prey Restraint


RPR ''ripper'' behavioural model, illustrated by a small dromaeosaurid. (A) grasping foot holds on to prey. (B) hypertrophied D-II claw used as anchor to maintain grip on large prey. (C) predator's bodyweight pins down victim. (D) beam-like tail aids balance. (E) low-carried metatarsus helps restrain victim. (F) ''stability flapping'' used to maintain position on top of prey. (G) arms encircle prey (''mantling''), restricting escape route. (H) head reaches down between feet, tearing off strips of flesh (may explain unusual deinonychosaurian dental morphology). Victim is eaten alive or dies of organ failure.

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0028964

[Halichoeres]

Aha! Thank you, Gwangi. @Faelrin to answer you question, I'm honestly not sure how that interacts with head stabilization. For an owl or kestrel, it's clearly useful in maintaining a visual lock on prey from a distance and during flight, but up close it might actually be a drawback if you have to reacquire focus every time you move your head. But maybe during the part of the hunt where you're up close it doesn't really matter and the prey is already doomed--sharks and some other fishes are pretty much completely blind in the last stages of a strike, but at that point the eyes have already done their job. I dunno, I'm speculating!

[Faelrin]

I guess the closest I can do is watch videos of extant hawks and eagles in RPR, and observe details. They might be the closest analogues we have despite having achieved flight, etc.

[andrewsaurus rex]

that tailed chicken experiment is fascinating.  And you can clearly see the thighs moving under the feathers.

were there any dinosaurs that did not have a tail?

[Halichoeres]

In the interest of invoking Cunningham's Law, I'm going to guess "no."

[andrewsaurus rex]

lol.....well at least you have a 50-50 shot of being correct.  Mind you, when  I make 50-50 guesses I find i'm wrong about 90% of the time. 

I've looked for a while and can't find any tailless dinos.  You'd think there would have been some, or one, given a dinosaur lineage evolved into birds.

[Halichoeres]

The closest thing I can think of is scansoriopterygids like Yi.