Cranial growth in Saimiri sciureus (Cebidae) and its alteration by nutritional factors: a longitudinal study

Ten male Saimiri sciureus boliviensis (Cebidae), born at the Centro Argentino de Primates (CAPRIM), were grown in captivity. At weaning (6 months old), five individuals were fed ad libitum on a 20% protein diet (controls). The other five animals were fed ad libitum on a 5% protein diet (malnourished). Animals were radiographed monthly. The length, width, and height of the anterior, middle, and posterior components of the neurocranium, and those of the masticatory, respiratory, and optic components of the face were measured. A pattern of high growth rate was observed in both the three facial and the middle neural components. The anterior and posterior neural components showed a pattern of low rate of growth. The growth behavior of each variable was also different. Lengths grew more than widths and heights in the facial components, whereas widths grew more than heights and lengths in the neurocranium. Malnutrition delayed growth in size and altered the normal shape changes. High-patterned variables, such as masticatory and respiratory lengths, and the anterior and middle neural widths were particularly affected. The masticatory and the middle neural components underwent the greatest growth arrest. The optic and the respiratory components suffered a mild effect. The anterior and the posterior neural components were affected to a lesser degree.