ON THE ORIGIN OF FLIGHT IN CHIROPTERA (MAMMALIA): DID GLIDING PRECEDE ACTIVE FLIGHT?

摘要

Results of the studies and publications of the last decades on the origin of active flight in bats and birds are rigorously analyzed (Norberg, 1985; 1999; Long et al., 2003; 2008; 2012; , 2013; 2014; and others) with expressed different views on the origin of bats and the emergence of powered flight in birds and bats. The main question discussed is whether or not gliding in bats had occurred prior to active flight. According to comparative morphological, embryological and cytological studies, the key morpho-functional alterations of the walking thoracic limbs of bat ancestors during the emergence and development of flapping flight are shown to have occurred in autopodia. The most significant of autopodial reorganizations seem to have been the elongation of the second to fifth metacarpals (Mc 2-5), this having served as a root cause for the formation of an embryonic interdigital membrane. The first finger was not involved in the evolutionary transformations of the wrist and thus was capable of providing locomotion (climbing tree trunks) at transitional stages in the evolution of walking limbs into the wing. The defended hypothesis is that gliding is a dead-end direction in terms of the development of active flight.