Researchers develop dinosaur-footed chicken embryos
One of the most widely accepted theories about bird evolution is that they are descended from dinosaurs. And according to the Science Daily portal, an experiment led by Brazil's João Botelho at the University of Chile - in which scientists were able to perform a kind of “reverse evolution process” in the laboratory - further reinforces the body of evidence that supports this principle. .
According to the publication, most modern birds have a kind of opposing big toe that allows them to cling to perch or hunt for prey as they fly. However in dinosaurs such as tyrannosaurus and allosaurus, these structures, besides being too small to touch the ground, were not as opposing as those of modern birds - more like dog and cat smears.
To find out how the "big toes" came about, scientists watched the development of paws in chicken and quail embryos while they were still in their eggs. They found that these limbs begin to emerge in birds just as dinosaurs do, but in birds their base - the metatarsus - begins to twist at a certain stage of development, causing the fingers to become opposing.
In addition, scientists also realized that compared to the other "fingers, " the expression of the genes that determine the maturing of the opposing big toe cartilage occurs much later in the embryo development process.
In this way, the big toes eventually retain many rapidly dividing stem cells over a longer period of time. And this immature cartilage, in turn, besides being highly malleable and plastic, is easily transformed by muscle activity.
The researchers realized that the "twisting" of the big toes coincides with the stage at which the embryos begin to move inside the eggs - and it is the muscular movement of animals that causes the metatarsal to rotate and bend so that the finger adopt the opposing position.
So the scientists used drugs to paralyze the muscles and prevent the animals from moving. As a result, the researchers interfered with the process of developing the embryos, causing instead of fingers to become opposing, to grow similar to those of dinosaur paws.
More than that, the reverse process allows researchers to better understand the morphological transformations suffered by birds as they evolved from their ancestors - the dinosaurs - over time.