xxiii. 7 FOSSIL TARSIOIDS 617 



placenta is of discoidal shape and haemochorial organization, with a 

 much reduced allantois, almost like that of apes and men. The amnion 

 is formed by folding. 



Some of these characters indicate a type of organization so similar 

 to that of anthropoids that the resemblance can hardly be entirely due 

 to convergence. Many of the monkey-like features of the head could, 

 however, be due to the large size of the eyes. Moreover, the reduction 

 of the turbinals has taken place differently in Tarsius and anthropoids. 



In its legs (Fig. 395) Tarsius shows considerable specialization for its 

 jumping method of progression, the fibula being fused with the tibia 

 and the calcaneum and astragalus elongated so as to provide an extra 

 leg segment while retaining the grasping foot. Both first digits can be 

 used for grasping and the digits bear adhesive pads; all have nails 

 except the second and third in the hind-limb, which carry claws used 

 for cleaning the fur. As in other jumping animals the ilium is very 

 long. There is also a long tail. 



The *Anaptomorphidae are fossil tarsioids found from Palaeocene 



to Oligocene in Europe and America. At least 20 genera are known, 



mostly from skulls and teeth; where limb bones are found they already 



have the tarsioid specializations. In most the eyes were large and the 



face short. The brain was like that of Tarsius but with olfactory regions 



better developed. The teeth of some (*PsendoIoris) were remarkably 



3.1.3.3 

 like those of Tarsius but of very generalized pattern ( v ) and 



tribosphenic (Fig. 383). Other lines were specialized, for instance by 

 reduction of the lower incisors and procumbency of the canines 

 {*Necrolemur). Some of these animals may have been close to the 

 primate ancestry, but it must be recognized that the tarsioids show 

 more similarity to the Anthropoidea than to the lemurs. We are 

 ignorant of tarsioid history from the Oligocene to recent times, but 

 it seems likely that they have remained an isolated stock, their rela- 

 tionship to higher primates being one of common ancestry in early 

 Tertiary times, when all these primates were so alike that it is best to 

 class them together as Prosimii, some of which went on to develop into 

 anthropoids (Fig. 416). 



7. Characteristics of Anthropoidea 



The monkeys, apes, and men form a natural group, almost certainly 

 of common descent from some Eocene population. They first appear 

 as fossils in the Oligocene and have flourished greatly since; Simpson 

 lists 66 genera in the suborder, of which only 30 are extinct; evidently 



