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February 5
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Deinonychus Walk Cycle by EWilloughby Deinonychus Walk Cycle by EWilloughby

This incredibly cool new study by Gossi et al, published today in PLOSone, has researched whether chickens walk differently if they have a long, heavy tail, reminiscent of the type of tail present in non-avian dinosaurs. Giving them such a tail artificially (while controlling for weight) actually changes their gait significantly, giving them more hip-driven locomotion and less knee-driven as in modern birds. Check out the paper, it’s open-access.

From the abstract:

Birds still share many traits with their dinosaur ancestors, making them the best living group to reconstruct certain aspects of non-avian theropod biology. Bipedal, digitigrade locomotion and parasagittal hindlimb movement are some of those inherited traits. Living birds, however, maintain an unusually crouched hindlimb posture and locomotion powered by knee flexion, in contrast to the inferred primitive condition of non-avian theropods: more upright posture and limb movement powered by femur retraction. Such functional differences, which are associated with a gradual, anterior shift of the centre of mass in theropods along the bird line, make the use of extant birds to study non-avian theropod locomotion problematic. Here we show that, by experimentally manipulating the location of the centre of mass in living birds, it is possible to recreate limb posture and kinematics inferred for extinct bipedal dinosaurs. Chickens raised wearing artificial tails, and consequently with more posteriorly located centre of mass, showed a more vertical orientation of the femur during standing and increased femoral displacement during locomotion. Our results support the hypothesis that gradual changes in the location of the centre of mass resulted in more crouched hindlimb postures and a shift from hip-driven to knee-driven limb movements through theropod evolution. This study suggests that, through careful experimental manipulations during the growth phase of ontogeny, extant birds can potentially be used to gain important insights into previously unexplored aspects of bipedal non-avian theropod locomotion.

This study has obvious implications for how non-avian theropods walked, so I could not resist doing a quick (1 hour or so) animation of a dromaeosaur loosely based on Deinonychus doing the dino-walk.
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Sekley Featured By Owner Jul 2, 2014
"Look I'm a little chicken!"
Azurehypnock Featured By Owner May 22, 2014  Hobbyist
Great animation.
Dinofuzz Featured By Owner Apr 1, 2014  Hobbyist General Artist
Brilliant! Like modern avian dinosaurs do, too! :D
FancyKarp Featured By Owner Mar 2, 2014  Hobbyist Traditional Artist
Open the  door! Get on the floor!
Galliraptor Featured By Owner Feb 22, 2014
awesome:) (Smile) 
Sasiadragon Featured By Owner Feb 13, 2014  Hobbyist General Artist
This is really cool, and I love your dino-walk! It's really cute with the wobbly head. I also really like how fluffy this thing is.
dewlap Featured By Owner Feb 10, 2014
This paper reminds me of a similar study by Carrano and Biewener (ref 7 from your link); is there a real different between the 2 experiments?

Carrano MT, Biewener AA (1999) Experimental alteration of limb posture in the chicken (Gallus gallus) and its bearing on the use of birds as analogs for dinosaur locomotion. Journal of Morphology 240: 237–249.
EWilloughby Featured By Owner Feb 10, 2014  Professional General Artist
Interesting - I see that the new PLOS paper cites the Carrano study, at least. I've just downloaded it and will give it a read in a bit. Very curious to see whether it reaches any sort of different conclusion. 
dewlap Featured By Owner Feb 10, 2014
For a moment I thought it was a follow up of the previous study then I realize it was written by different authors...

I haven't read the PLOS paper yet (only skimming through it); perhaps they actually did reach a different conclusion (like a different angle on the flexion of the knees maybe).
Stegoraptor Featured By Owner Feb 8, 2014  Hobbyist Traditional Artist
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