Tuesday, 4 March 2014
New Proof for the Dino-Bird Connection: Tails on Chickens
How could evolutionists prove that birds have evolved from dinosaurs? Though the fossil evidence is murky and the emphasis tends to be on the philosophical dimension, one cannot blame them for not trying.
A recent paper in PLOS ONE by Bruno Grossi and colleagues attempts to take a fresh approach. They put artificial tails on chickens and observed how they walked.
Their evolutionary bias becomes obvious in their paper:
“Birds have inherited numerous locomotory traits from their dinosaur ancestors, including bipedalism, fully erect posture, and parasagittal hindlimb movement, which are not shared with the other extant group of archosaurs, the crocodilians. Therefore, it is appealing to think of birds as a model system to gain insights into aspects of non-avian dinosaur biology that are hard to study directly from fossil material, such as the relationship between limb morphology, posture, and locomotion.”
So, why did they do what they did?
“Living birds …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.”
Thus, if real birds cannot provide evidence for their view, they can always use fake ones:
“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.”
There was a time when science was a quest for the truth. However, when it is tainted with evolutionary thinking, it becomes a means for bolstering up naturalistic ideology.
Grossi, Bruno et al. 2014. Walking Like Dinosaurs: Chickens with Artificial Tails Provide Clues about Non-Avian Theropod Locomotion. PLOS ONE 9 (2) (February).