Chickens with Artificial Tails Provide Clues about Non-Avian Theropod Locomotion

["Richard W. Travsky" <rtravsky@uwyo.edu>]

Came across this by chance. Did not see it in the archives.

With video. Has a creepy feel...

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0088458

Walking Like Dinosaurs: Chickens with Artificial Tails Provide Clues 
about Non-Avian Theropod Locomotion

Bruno Grossi, José Iriarte-Díaz, Omar Larach, Mauricio Canals, Rodrigo 
A. Vásquez
Published: February 05, 2014
DOI: 10.1371/journal.pone.0088458

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 link

http://io9.com/heres-a-chicken-wearing-a-prosthetic-tail-to-walk-like-1517456040

has part of the video as a repeating gif.