Postnatal development in known-age captive orangutans was studied by collating new data from seven orangutans at Chicago Zoological Park, Brookfield, Illinois, with published and unpublished data from 76 additional captive orangutans. Norms were tabulated for deciduous and permanent dental emergence. Growth curves for weight and linear dimensions in females and males were compared in captive-reared and wild-reared subjects. Hand-reared and mother-nursed captives were compared with respect to dental emergence and weight increase. Differential relative growth of extremity segments was investigated. Pedigree data are presented relative to genetics of hallucal nail absence. Males of various ages were compared with respect to testis size and location and cheek-pad development. an undocumented weight curve to age 10 yr (sex unspecified) has been published by Reynolds [1967, p 741. Further information concerning weight in known-age young orangutans and age of emergence of deciduous teeth has been published by several authors, most notably Seitz [1969a, p 821 and Lippert 11977, pp 220, 2231. In addition, the important file of data on development in young orangutans at Yerkes Regional Primate Center is currently being analyzed for future publication by Dr Terry L. Maple (personal communication). Lacking until now, however, are documented weight curves from birth into adulthood, growth curves for linear dimensions, and composite dental emergence norms. The present study of orangutan development resulted from an opportunity to examine and measure seven captives at Brookfield Zoo on the occasion of their relocation into new quarters.
MATERIALS AND METHODSSeven orangutans (Pongo pygmaeus) [Hoppius, 1760, p 681, ranging in age from 7 months to 23 yr, were examined at the Chicago Zoological Park, Brookfield, Illinois (Brookfield Zoo), on January 19, 1983 (Table I). The six largest subjects were studied while they were under anesthesia to facilitate their relocation; the smallest one was restrained manually. Weights of the animals, unfed since the preceding day, were taken by zoo staff members. Dental examinations were conducted by a team from the Loyola University School of Dentistry.We followed standard mammalogical procedure (Hall, 1981, p 11261 in measuring length of the ear (notch to apex) and length of the foot (heel to tip of longest toe). Length of the hand was measured in a manner comparable to that used in measuring length of the foot. Other measurement procedures were specially adapted for application to living orangutans, as indicated below:Crown-heel length (= standing height) was measured by extending supine subject at full length, projecting perpendicularly from plane of vertex and plane of heels to substrate, marking projections on substrate, and measuring by tape the linear distance on the substrate between the vertex projection mark and the heel projection mark. This is essentially the same technique used by Hornaday [1910, p 4051 to measure orangutans in the field. This measurement also approximately corresp...
