Genus Varecia : anatomy, morphology, and pathology
Orellana, Elise R.
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An anatomical normal was established for the forelimb and hindlimb of the Genus Varecia through observation of skeletal remains and a detailed dissection of the musculature of a black and white ruffed lemur, Varecia variegata. This was used as a healthy state for comparison with a red ruffed lemur, Varecia rubra, displaying a periosteal disease affecting the long bones. This disease presented as large lesions growing along the diaphyses and epiphyses of the ulna, radius, tibia and fibula as well as on the carpals, metacarpals, tarsals, metatarsals, and phalanges. Dissection showed that these lesions avoided the points of origin and insertion of the limb musculature. Instead, the calcified lesions grew over the tendons and some muscle in the wrist and ankles reducing dexterity and range of motion in climbing and walking activities. This study determined the initial diagnosis of primary hypertrophic osteoarthropathy to be a misdiagnosis based on the absence of the three main symptoms of the disease: finger clubbing, pachydermia, and periostitis. Instead the location, size, and progression of the bony lesions make Nora's lesions (bizarre parosteal osteochondromatous proliferation) are more appropriate diagnosis. The skeletomuscular data provided in this work allow for Varecia to be used as a model for morphological studies, in disease recognition and diagnosis, and answered questions regarding the effects of the periosteal disease described.