No abstract

No abstract

Morphoecological Peculiarities of Pelvis in Several Genera of Rails with Some Notes on Systematic Position of the Coot, Fulica atra (Rallidae, Gruiformes). Bogdanovich, I. A. - Some features of pelvic and hindlimb morphology of several ecologically different species of rallids are studied. Adaptive significances of these features are revealed. A special attention is paid to the hindlimb skeleton of the Coot (Fulica atra, Linnaeus, 1758), which retained the locomotor universalism despite adaptations to swimming and diving.

Pr eadaptive Stage for Flight Origin. Bogdanovich, I. A. -Bipedalism as a preadaptive stage for bird's fl ight is considered. We attribute the formation of full bipedalism in bird ancestors with pelvic limbs transition from segmental to parasagittal position. Th is transition was fast enough. We can assume that the pectoral limbs freed from the support remained while laterally spaced and gave set of transformations with diff erent degrees of reduction. Th us morphologically "winglike" version of the thoracic limbs could appear. Parasagittal pelvic limbs allowed birds ancestors fast and maneuverable running, while the movements of free and highly movable thoracic limbs (feathered unrelated to fl ight) provided dynamic stability of the animal. In addition, their fl uttering movements facilitate hopping from one branch to another and the descent from the trees. On the bottom branches protobirds could jump with perching just by the pelvic anisodactyl limbs, not by thoracic as had supposed earlier. Ac tive interaction of the primary simple feathers with air as well as its protective function could become an impetus for their transformation into diff erentiated structures. Unlike gliding (as preadaptive stage for active fl ight) bipedalism with free feathered forelimbs provides per se parallel development of two autonomous enough locomotor systems of birds (fl ight and terrestrial locomotion) and extensive adaptive radiation of representatives of the class. Key words: bipedalism, fl ight, birds.Despite the long history of the study of the origin of birds and fl ight, the origin and subsequent evolution of feathered wings remains one of the most controversial topics in the vertebrate paleontology (Kaiser, Dyke, 2014). For example, the question of preadaptive stage preceding the fl ight is not entirely unambiguous. As such the terrestrial, through the running and jumping (Dececchi et al., 2016), and arboreal, through gliding (Czercas, Feduccia, 2014) hypotheses are still being discussed.Up to a certain time it was common belief that the way of becoming the birds as a taxon, the transformation of thoracic limbs into wings led to bipedalism (Du Brul, 1962;Ilichyov et al., 1982). Today, the transition to bipedal locomotion with full exemption of thoracic limbs from the support function is considered as a stage that preceded the origin of fl apping fl ight of birds (Long et al., 2003;Kurochkin, Bogdanovich, 2008, 2010. In another point of view the gliding (when in process of air locomotion both fore and hind limbs are involved) is much better suited as a transitional stage to fl apping fl ight than bipedalism, which only leads to reduction of muscles and thoracic limbs as whole (Panyutina et al., 2015). It is impossible not to admit that the exemption of the thoracic limbs from the support-locomotor function was followed by their partial reduction. It is known that reduced organs demonstrate a very large and diverse variability of their parts due to the termination or weakening of natural selection and preservation of indep...