Skin bumps on lizards, crocodiles, snakes resolve confusing debate
N. Di-Poï, M. Milinkovitch, A. Tzika/UNIGE 2016
Hair, scales and feathers arose from one ancestral structure, a new study finds.
Studies in fetal Nile crocodiles, bearded dragon lizards and corn snakes appear to have settled a long-standing debate on the rise of skin coverings. Special skin bumps long known to direct the development of hair in mammals and feathers in birds also turn out to signal scale growth in reptiles, implying all three structures evolved from a shared ancestor, scientists report online June 24 in Science Advances.
In embryonic birds and mammals, some areas of the skin thicken into raised bumps. Since birds evolved from ancient reptiles, scientists expected that modern snakes, lizards and crocodiles would have the same structures. A study at Yale University last year found that one protein already known to be important in hair and feather development is also active in