№ 4 | 2018 год | страницы 25-29
BIPEDAL HOPPING IN BIRDS AND RODENTS: MORPHOLOGICAL AND EVOLUTIONARY ASPECTS
Tver State University, Tver
Hopping in birds is confined exclusively to the perching birds, belonging to the order Passeriformes. Being an adaption to move in canopies, it resulted in the reduction of certain muscles and structures acting in the single support phase of the locomotor cycle. These muscles and structures are not regained by passerines which switched to running (larks, pipits, wagtails). Passerines also lost most of the intrinsic muscles of the foot as they brought digits into the parasagittal plane to ensure the firmer grip of the perch. Bipedal saltation in rodents evolved as an adaptation to escape from predators in sparsely vegetated areas. It has resulted in morphological changes, convergent to those of hopping birds. Muscles responsible for any other movements of the limb segments than flexion-extension are underdeveloped. The reduction of digits and fusion of metatarsalia reach their extreme in Jaculus orientalis, which lost all the intrinsic muscles of the foot.
birds, rodents, convergence, hind limbs, hopping, musculature