EVERYDAY SCIENCE

Detailed explanation-1: -Human hair, bird feathers came from reptile scales | Science | AAAS.

Detailed explanation-2: -Feathers are complex and novel evolutionary structures. They did not evolve directly from reptilian scales, as once was thought. Current hypotheses propose that they evolved through an invagination of the epidermis around the base of a dermal papilla, followed by increasing complexity of form and function.

Detailed explanation-3: -Mammalian hairs, avian feathers, and reptilian scales are homologous structures inherited, with modification, from their shared reptilian ancestor’s scales, according to a new study published Friday in Science Advances.

Detailed explanation-4: -Feathers and scales are made up of two distinct forms of keratin, and it was long thought that each type of keratin was exclusive to each skin structure (feathers and scales). However, feather keratin is also present in the early stages of development of American alligator scales.

Detailed explanation-5: -A bird has scales over its legs and have many characters, including skull and skeleton, that are very reptilian. They are highly modified scales composed of beta keratin. A feather is a scale in which a long center shaft, the rachis, is the dominant feature.