Search Results for: Reptiles
different classification based on molecular data has been developed (the so-called sibley order) and is gaining acceptance. species and habitats the estimated number of living bird species is often put around ten thousand, but ranges from – . this compares to about species of mammals and species of reptiles
called keratin . these fibrous structural proteins form the hard, but non-mineralized structures found in bird feathers, beaks, and claws, as well as reptilian claws, shells, and scales, and mammalian hair (including wool), nails, claws, horns, and hooves of mammals. the β-keratins used by birds and reptiles...
https://www.newworldencyclopedia.org/entry/Bird