XX 



ft 



MARSUPIALS 





1. Marsupial characteristics 



The pouched mammals are essentially very similar to placentals, 

 though they undoubtedly diverged from some early stage of the main 

 mammalian stocks. They parallel, in the isolation of Australasia, the 



Fig. 330 



f n c m* m 



Fig. 331 



Figs. 330-1. Skulls of thylacine (330), and rat kangaroo (Bettongia) (331). 

 (From Flower and Lyddeker, Mammals, Living & Extinct, A. & C. Black, Ltd.) 



adaptive radiation accomplished in other parts of the world by the 

 placentals. Many of their features are specialized, so that they re- 

 present not a stage on the way to placental evolution but a specialized 

 side branch. Today some 230 species are found in the Australasian 

 region, and there are successful representatives in North and South 

 America. In Eocene times they occurred in Europe. 



The skull shows many characters found also in Insectivora and 

 other early mammalian groups (Figs. 330-1). The brain-case is small 



