First Description of the Fur of Two Cubs of Fossil Cave Lion Panthera spelaea (Goldfuss, 1810) Found in Yakutia in 2017 and 2018.

The first description of well-preserved fur of one male and one female cubs of the fossil cave lion Panthera spelaea (finds of 2017-2018, Semyuelyakh River, Yakutia, Russia) is presented in comparison with the fur of two cubs (a male and a female) of the extant African lion P. leo and adult lions of both species: the color, differentiation, configuration, microstructure, and internal design of hair of different categories are considered. The coat of the cave lion is similar but not identical to that of the African lion, because it contains a high thick undercoat of spiral-shaped thick and airy down hair. This difference is most pronounced in the cave lion cubs, in which, however, the fur is not differentiated to the same extent as in the adult. The microstructure of hair is species-specific and subject to intraspecific age-related variability. Adaptive features of the hair structure in the cave lion are noted.

Papillomatous Skin Netting of Cetaceans (Cetacea: Delphinapterus leucas, Balaena mysticetus, and Eschrichtius robustus) and Sirens (Sirenia: Trichechus manatus and Dugong dugon).

The structure of the papillomatous junction between epidermis and dermis (papillomatous netting, PN) in the skin of cetaceans (white whales, bowhead, and gray whales) and sirens (American manatee, dugong) was studied and compared using histophysiological and morphogeometric methods. The relative extent of PN development proved to be similar in members of both orders, but significant differences were found in PN configuration, the volume of "free area of grille", the degree of skin vertical compression, and skin density, which influence buoyancy. The differences are discussed from the viewpoint of species biology.

Architectonics of the hair of sled dogs of Chukotka.

Architectonics of guard hairs from dogs of recent breeds, mongrel sled dogs, and fossil dogs from ancient settlements of Chukotka have been investigated using scanning electron microscopy. Distinct features of hair structure important for adaptation, including the adaptation to harness in sled dogs, were identified. Hairs of Chukchi sled dogs were most similar to those of the fossil dogs.

The first finding of a rhinoceros of the Genus Stephanorhinus in Arctic Asia.

The first skull of a rhinoceros of the genus Stephanorhinus has been found above the Arctic Circle on the middle Chondon River (Yakutia, Russia). This is the northernmost finding that extends significantly the genus range and provides additional information about the diet and environment of a genus representative. Plant remnants from the maxillary tooth cavities were identified as belonging to trees (Larix, Betula), shrubs (Ericaceae), mosses (Aulacomnium sp., Polytrichum sp.), herbs (Dicotyledones) and grasses (Poaceae), but not to sedges (Cyperaceae). The pattern of attrition of teeth and marks on the chewing surface enamel indicate diverse nourishment. Chondon rhinoceros lived in under Arctic-like climatic conditions, with rather limited food resources.

Summer molting of bowhead whales Balaena mysticetus Linnaeus, 1758, of the Okhotsk Sea population.

In bowhead whales summering in Ulbanskiy Bay of the Okhotsk Sea, molting of epidermis has been found and histologically confirmed. The outer layer of the molting whale epidermis is longitudinally stratified and rejected in the form of relatively large plates up to several millimeters thick, each representing a lamellar formation consisting of longitudinal rows of parakeratocytes with degenerated nuclei, numerous pigment granules, and lipid inclusions. Molting intensity is correlated with the level of proliferation and regeneration of all epidermal layers, which helps to maintain the optimal skin thickness.

Hair microstructure of the first time found calf of woolly rhinoceros Coelodonta antiquitatis.

Hair microstructure of the first calf of the woolly rhinoceros Coelodonta antiquitatis found in Sakha in 2014 (the neck and hind leg hair) was examined by the light and electron scanning microscopy. The calf hair features were compared with those of two adults studied earlier. The calf coat color was much lighter than in adults, from pale ashy to blond. The extent of hair differentiation, dimensional and pigmentation indices were lower in the calf than in adult rhinoceroses. There was no medulla in the calf hairs, while in those of adults it was occasionally found. The cortical and cuticular layer microstructure was similar in all the animals compared. In both calf and adult hairs, there were traces of mechanical damage.

Scanning electron microscopy of the iridescent feather architectonics of the white throated needletail (Hirundapus caudacutus, Apodidae, Aves).

By means of SEM, it has been demonstrated that structural coloration of the needletail Hirundapus caudacutus depends on architectonics of iridescent feathers of the bird.

[The morphogenesis of mammalian cutaneous glands in evolutionary perspective].

The morphogenesis of mammalian cutaneous glands is considered based on the analysis of the literature and our own original data with the focus on the issues of gland polymorphism and specific features in postnatal development (from the case study of circumanal hepatoid glands of newborn domestic dogs), including the features reflecting the evolutionary relationships of various types of cutaneous glands. The hepatoid glands are a component of the glandular complex ofthe hair follicle, which also includes sebaceous and sweat glands; have a specific structure; and produce protein secretion by a merocrine pathway. Characteristic of these glands are wide polymorphism, sex- and age-related differences in the degree of development, occurrence in only a few phylogenetically related mammalian taxa (even-toed ungulates and carnivores); and a signaling type of their secretion. The data support the "generative concept," relying on the idea of a separate and independent origination of diverse derivatives of the external integuments.

[Decorative forms of hamsters Phodopus (Mammalia, Cricetinae): an analysis of genetic lines distribution and peculiarities of hair changes].

Three species of dwarf hamsters (genus Phodopus, family Cricetidae) inhabit some regions of Russia, Kazakhstan, Mongolia, and China, each having quite extensive range. In recent decades, the dwarf hamsters became widely spread all over the world, initially as laboratory animals and later as popular pets. By now, there is lot of decorative breed lines and colored forms of these animals. Comparison of mtDNA nucleotide sequences of dwarf hamsters acquired in pet shops of some countries in Europe, South-East Asia and North America with distribution of mtDNA haplotypes within natural ranges showed the limitation of decorative line founders' points of origin by one region for each of the species. All haplotypes found in decorative Dzungarian hamsters (Ph. sungorus) purchased ounside Russia coincide with or are significantly close to haplotypes spread in the southern part of West Siberia (Russia) and adjacent regions of Kazakhstan; haplotypes of decorative Campbell's hamster (Ph. campbelli) belong to haplogroup of this species natural populations inhabiting South Tyva (Russia); and all studied decorative Desert hamsters (Ph. roborovskii) had one hapotype specific for South-Eastern Kazakhstan. The review of the history of researches on dwarf hamsters biology allows to determine delivery of hamsters from mentioned regions to scientific laboratories and zoos by certain expeditions and/or researchers. Unlike hamsters with natural hair color, the colored hamsters have no normal hair. Their hair is dull and straggly. The hair differentiation (presence of different hair types and their size characteristics) gets broken and results in deformation, bending, and splitting of the shaft, cracks in cuticle, change of configuration and location of medulla, uneven development of cortex. It is assumed that these destructive changes are associated with genetic characteristics of these hamsters' colored forms.

[Peculiarities of the contour feather microstructure in the Corvidae family].

The results of comparative electron microscope study of the fine structure of the definitive contour feathers often Crows species (Perisoreus infaustus, Garrulus glandarius, Cyanopica cyanus, Pica Pica, Podoceus panderi, Nucifraga caryocatactes, Corvus monedula, C. frugilegus, C. cornix, C. corax) are presented. The results of the research allowed us to conclude that crows, along with the traditional elements of feather architectonics, have a number of species-specific microstructure characteristics that are taxonomically important.

[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.