Scientists solve 320-million-year mystery of reptile bone armor

Reptiles have been growing armor in their skin on and off for hundreds of millions of years, but scientists never fully understood how it evolved. A massive new evolutionary study shows these skin bones appeared independently in multiple lizard groups rather than coming from a single armored ancestor. Even more astonishing, Australian goannas lost this armor long ago — then evolved it back again millions of years later.

Raccontata dasciencedaily.com