Epiphyseal union,tooth eruption,and sexual maturation in the common tree shrew,with reference to its systematic problem

The epiphyseal union, eruptive sequence of the permanent teeth, and sexual maturity are examined in 150 common tree shrews (Tupaia glis), and are compared with those in other mammals including primates. The sequence of epiphyseal union is: elbow-hip-ankle-wrist-knee-shoulder. The sequence of epiphyseal union in mammals is not so fixed as has been previously considered. The eruptive sequence of the permanent teeth in the common tree shrew is more similar to that of insectivores than primates. The gonads are examined histologically to determine the sexual maturation. The order of completion of these three developmental aspects is also investigated and is compared with those in other mammals. Although the tree shrews have many similarities with platyrrhines in the development of the eco-sensitive organs such as the epiphyses of the extremities, their inclusion in the order Primates is still doubtful.