[Microstructure of skin derivatives as a reflection of phylogenesis of vertebrates]

The possibility of using separate signs of microstructure of skin derivatives to understand phylogenesis processes at various hierarchical levels on the example of elasmoid scale of bony fish, feathers of Paleognathae birds, hepatoid glands, and mammal hair was demonstrated and discussed. It was shown that (1) the presence of toothed sclerite growths on the surface of the elasmoid scale of bony fish provided with a central canal can serve as a proof of the evolutional relation of placoid and elasmoid scales; (2) particularities of the microstructure of feathers of Paleognathae birds accord with the branching of their phylogenetic tree; (3) the development of hepatoid glands suggests a phylogenetic relatedness of ancestor forms of cavicorns, Canidae, and Felidae; (4) the subtle construction of horse hair shows the succession of the ancient E. lenensis and northern aborigine breeds of the domestic horse, the direction of the historical process of horse domestication and adaptation of these animals to environmental conditions; (5) similarities in the microstructure of hair of the giant and red panda and bears indicate their evolutional links with Ursidae rather than raccoons.