Reptile Scale Paradigm: Evo-Devo, Pattern Formation and Regeneration

The document reviewed the reptile integument as an experimental model for understanding the evolution and development (Evo-Devo) of amniote integuments. It highlighted that reptiles, as the first amniotes, provided insights into the evolution of mammal hairs and feathers from Therapsid and Sauropsid reptiles, respectively. The study emphasized the adaptation of reptilian skin to terrestrial life, including the development of a multi-layered stratum corneum for protection and diverse scale types for mechanical defense. The convergent evolution of hair and feather follicles was noted, with both forming growth units that allow for elongation, molting, and regeneration. The unique arrangement of reptile scales and pigment patterns made them ideal models for studying pattern formation. The document called for further molecular analyses to understand the gene regulatory networks involved in producing complex ectodermal organs, suggesting that reptile scales could fill gaps in the understanding of amniote integument evolution.