Comprehensive molecular and cellular studies suggest avian scutate scales are secondarily derived from feathers, and more distant from reptilian scales

The study investigated the evolutionary relationship between avian feathers, avian scales, and reptilian scales by comparing molecular and cellular profiles in chicken feathers, chicken scales, and alligator scales. It was found that chicken scutate scales shared similarities with chicken feathers during early morphogenesis, while alligator scales were significantly different at the molecular level from both chicken feathers and scales. Additionally, a diffuse stem cell niche was identified in both chicken and alligator scales, which is involved in alligator scale regeneration, whereas avian feathers had a more condensed stem cell niche. These findings suggested that chicken and alligator scales evolved independently through convergent evolution.