Dermo-Epidermal Interactions in Reptilian Scales: Speculations on the Evolution of Scales, Feathers, and Hairs

The paper discussed the role of dermo-epidermal interactions in the formation of reptilian scales and speculated on the evolutionary development of scales, feathers, and hairs. It highlighted that dermal cells connect to specific epidermal areas, forming regions where morphoregulatory molecules are exchanged. These regions' positions change during development, potentially leading to different appendages based on genetic makeup. The study hypothesized that variations in these interactions' localization and extension could explain the evolution from large scales in early amniotes to the specialized structures in modern reptiles, mammals, and birds, such as hard keratin scales, hair, and feathers.