The evolutionary link between dinosaurs and birds is now firmly established. Birds aren't just related to dinosaurs, they are living dinosaurs. Modern chickens have a lot in common with their therapod ancestors, but there are key differences. Researchers added a weighted prosthetic tail to a chicken in order to get a better idea of how dinosaurs moved. The study was led by Bruno Grossi from the Universidad de Chile and the results were published on PLOS ONE.
There are many similarities in the leg structure of theropod dinosaurs and modern birds, including bipedalism and digitgrade movement (they walk on their toes). Because of this, there is a lot that researchers can learn about dinosaur movement through studying birds. The largest disparity between the way a Tyrannosaurus Rex and a chicken would walk is the tail. While most bird tail feathers are light and can be used kind of like a rudder in flight, dinosaur tails were much heavier and were used for balance or protection. This weight difference alters the center of body mass as well as positioning of the knee and range of movement in the femur.
To remedy this difference the researchers attached weighted tails made from clay and a wooden stick and affixed it to the bird with Velcro. The tails were applied two days after hatching and were replaced about every five days in order to keep up with the chickens’ growth and to maintain the tail at about 15% of the total body mass.
At the age of 12 weeks the chickens were videotaped in order to monitor their gait. Compared to a control group, the chickens with weighted tails showed a decreased range of motion in the knee, though the range of motion in the femur increased threefold to compensate. The average femur length was actually marginally larger for those with the false tails.
Though it might seem like using Velcro to attach clay and wooden sticks to chickens is somewhat unnecessary, this is the most realistic model that researchers can get to better understand how dinosaurs moved. This will assist scientists in understanding limb positioning and locomotion of long-extinct bipedal dinosaurs.