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Rhea Americana (rhea + americana)
Selected AbstractsBipedal locomotion in ratites (Paleognatiform): examples of cursorial birdsIBIS, Issue 4 2000ANICK ABOURACHID The gaits of five Ostriches Struthio camelus, seven Emus Dromaius novaehollandiae, two Greater Rheas Rhea americana, two Southern Cassowaries Casuarius casuarius and one Brown kiwi Apteryx australis were filmed at zoological parks. Locomotor parameters were measured using footprints on sandy tracks and video records. Osteological measurements were made on skeletons of the pelvic limbs. All of these terrestrial birds shift from wallking to running at a relative speed below 1. However, they show two different locomotor patterns: the Brown Kiwi increases its speed by increasing its stride length, mainly by increasing the protraction angle. Its hindlimbs make a flexed jointed chain system, its centre of mass is anterior, its femurs are long and the knees act in yield whereas the distal joints act in propulsion. Other ratites, particularly Ostriches, increase their speed by increasing frequency. Their centre of mass is close to the hip, their hindlimbs have an extended jointed chain system with a short erect femur, maximizing a gravity-powered system. [source] The Hindlimb Muscles of Rhea americana (Aves, Palaeognathae, Rheidae)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2010M. B. J. Picasso With 13 figures Summary The Greater Rhea is the largest cursorial Ratitae bird native to South America. Due to its increasing importance in farming and therefore in the sustainable use of this species, a comprehensive knowledge of their anatomy is essential. The goal of this study was to provide an anatomical description of the hindlimb muscles of Rhea americana. Six adult birds of both sexes were macroscopically studied analysing the origin and insertion of thigh and shank muscles. The thigh showed the highest number of muscles, whereas the shank showed the lowest number; this feature minimizes inertia and allows achieving high stride frequencies. The muscles of the shank showed long tendons of insertion that reduce the energetic cost during running. The major muscles responsible for extension of the hip and the ankle joints were massive and robust indicating their importance for cursorial locomotion. The pelvic limb muscles of Rhea americana resemble those of other cursorial Ratitae and their features are consistent with specialization for high-speed locomotion. [source] Macroscopic and Microscopic Anatomy of the Oviduct in the Sexually Mature Rhea (Rhea americana)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2008R. C. Parizzi Summary The morphological characteristics of the oviduct of 12 sexually mature rheas (Rhea americana) were studied. Only the left oviduct is developed as a long tube with a length of 122 ± 23.1 cm, and is subdivided into infundibulum (15.2 ± 4.0 cm), magnum (63.3 ± 9.4 cm), isthmus (5.6 ± 3.1 cm), uterus (16.0 ± 4.2 cm) and vagina (11.5 ± 1.4 cm). The mucous membrane of the oviduct, as a whole, possesses luminal folds covered by ciliated columnar epithelium with secretory cells. The infundibulum part presents a cranial opening with thin and long fimbriae with few tubular glands in caudal tubular portion. In the magnum, the largest portion of the oviduct, the folds are thicker and are filled with tubular glands. The isthmus is short and presents less bulky folds and a few tubular glands. A bag-shaped uterus in the cranial area shows thin folds, and in the caudal region (shell gland) more ramified folds with few tubular glands. The vagina has long luminal folds and a thick muscular tunic; no glands with sperm-storage characteristics have been observed. In conclusion, the oviduct in sexually mature rhea has morphological similarities with the other species of birds already described; however it presents its own characteristics to produce a big egg. [source] | ||||||||||