86 citations,
April 2009 in “Journal of anatomy” Hard skin features like scales, feathers, and hair evolved through specific protein changes in different animal groups.
72 citations,
December 2018 in “Journal of Experimental Zoology Part B Molecular and Developmental Evolution” Corneous beta-proteins evolved uniquely in reptiles and birds, forming scales, claws, beaks, and feathers.
17 citations,
June 2012 in “Journal of experimental zoology. Part B, Molecular and developmental evolution” Hair in mammals likely evolved from glandular structures, not scales.
15 citations,
July 2004 in “Journal of morphology” Monotreme hair structure and protein distribution are similar to other mammals, but their inner root sheath cornifies differently, suggesting a unique evolution from reptile skin.
36 citations,
November 2019 in “Molecular biology and evolution” Cysteine-rich keratins evolved independently in mammals, reptiles, and birds for hard skin structures like hair, claws, and feathers.
4 citations,
June 2023 in “Journal of developmental biology” The skin systems of jawed vertebrates evolved diverse appendages like hair and scales from a common structure over 420 million years ago.