Feathers, Hair, Scales Evolved from One Ancestor

The coverings all developed from a single primordial structure.

Published On 06/24/2016
2:00 PM EDT
Placodes (spots stained in dark blue by the expression of an early developmental gene) are visible before the development of hair, scales and feathers in (from left to right) the mouse, the snake, the chicken and the crocodile. Credit: UNIGE 2016 (Tzika, Di-Poï, Milinkovitch)
Photo: This picture shows (from bottom to top) bearded dragons that are: "normal" (wild-type), with reduced scales and scaleless. Credit: Michael C. Milinkovitch 2016