. The Ecology of arboreal folivores : a symposium held at the Conservation and Research Center, National Zoological Park, Smithsonian Institution, May 29-31, 1975 . log,. Figure 1. Frequency distribution of size classes for Mammalian Genera. An average size was calculated for each polytypic genus by determining the mean head and body length based on the average value for the two extreme values within the genus. This figure then is based on a mean value which may not characterize the true mean for a genus but will give an idea of the size class distribution. The distribution for arboreal herbiv
. The Ecology of arboreal folivores : a symposium held at the Conservation and Research Center, National Zoological Park, Smithsonian Institution, May 29-31, 1975 . log,. Figure 1. Frequency distribution of size classes for Mammalian Genera. An average size was calculated for each polytypic genus by determining the mean head and body length based on the average value for the two extreme values within the genus. This figure then is based on a mean value which may not characterize the true mean for a genus but will give an idea of the size class distribution. The distribution for arboreal herbivore genera is crosshatched. The range at the bottom of the figure illustrates the range for arboreal mammals. Ordinate = frequency; abscissa = logio of average head and body lengths in millimeters. and that set of arboreal mammals which are also folivores is included in the same figure. As can be seen, arboreality does indeed set certain constraints on the size in terms of the upper limit that an animal can reach. Additionally, arboreal folivores seem to have a lower limit on size. As is discussed by McNab (1978), this limit on size in folivores may in some way be bound up with the efficiency of energy extraction from leaves, problems of detoxification, and the problems of heat loss in mammals which are below a certain critical size limit (see also Parra, 1978). Ingestion and mastication The ingestion of leaves and stems may involve the use of the tongue, lips, teeth, and forepaws. For many arboreal herbivores, such as the sloth, the forepaws may be used to bring a branch of leaves within reach of the mouth where the leaf is bitten off using the teeth; the lips are little involved in the initial manip- ulation of the leaf itself. This is in contradistinction to many terrestrial browsing herbivores which feed upon leaves, such as Rhinoceros, Tapirus, Elephas, and Giraffa, where the lips, proboscis, or tongue are commonly employed in stripping leaves from stems. The teeth are all
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Keywords: ., bookcentury1900, bookcolle, booksubjectleaves, booksubjectmammals
