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Scientists say they have created chicken embryos with the legs of long-dead dinosaurs.
Technically, chickens already have dinosaur legs because chickens, like all birds, are dinosaur descendants. But these unborn chickens have ancient dinosaur legs, the likes of which our planet has not seen in ages.
Though dinosaurs species are long gone, some branches of the dinosaur family managed to pass on their traits. One branch produced the oldest common ancestor of all living birds, the Archaeopteryx.
Chickens Strut Their Stuff
By studying birds, or "avian dinosaurs" as some scientists say, people can learn about the dinosaurs that became extinct. One recent study used chickens to better understand how earlier dinosaurs may have strutted around back in the day.
Back then, dinosaurs had big tails, so scientists stuck toilet-plunger-like fake tails on some chicken butts to see how the animals would walk. They kind of strutted like dinosaurs, shifting their weight forward with wide and heavy steps.
But a chicken with non-chicken-dinosaur legs is a brilliant feat of genetic engineering. The chickens were developed by scientists at the University of Chile and are described in a paper published this month in the science magazine Evolution.
Meaty Chicken Legs
Modern birds have leg bones that are a tad different from those in their ancient ancestors. The fibula, one of the two leg bones below the knee, was long and tube-shaped in older dinosaurs. It reached all the way down to the ankle. In modern birds, this bone is thinner and shorter relative to the other bones in the leg.
Modern birds still have much of the same DNA as their ancient dinosaur ancestors. While growing in the egg, that ancient DNA shows up. For a short time, the chicken fibulas look very dino-like. But once the leg bone gets the signal that this is a chicken, not an ancient dinosaur, the fibula turns into a chicken leg bone before the chick is ready to hatch.
The researchers, led by Joâo Botelho, skipped this step. They inhibited a gene to stop the legs from maturing into normal chicken legs. Once they turned off the gene, the leg bones did not get the signal to become chicken legs, which we call drumsticks. They matured into dinosaur legs instead.
"Not only do we know a great deal about bird development, but also about the dinosaur-bird transition, which is well-documented by the fossil record," study author Alexander Vargas said in a statement. Scientists can explore the biological connection between birds and dinosaurs in the lab, Vargas said.
Pecking Order
Before chicken embryos with dinosaur legs, Vargas' team has tweaked other genes. They made chicken embryos without the perching toe that modern birds have. A group at Yale modified beak-related genes to produce the kind of reptilian snout we associate with "true" dinosaurs.
All of this is possible because of the underlying genetic similarities between birds and their dinosaur ancestors. As scientists get better and better at using the gene editing, making changes like these — silencing or activating a few genes to bring an animal closer to its ancestors — may become routine.
But let's not count our dino-chickens before they have hatched: For now, none of the experiments have attempted to produce living animals from the tweaked embryos.