172 BRITISH MAMMALS 



to return to the common origin of the tiger and Machairodont 

 one must travel back to the most primitive cats of the Upper 

 or Middle Eocene. 



The Machairodonts had retractile claws. The earlier forms 

 were nearly plantigrade, the latter digitigrade, but not quite so 

 markedly as the modern cats. The claws of the largest species 

 must have been even more terrible weapons than those of the 

 lion and tiger, which look feeble in comparison ; and the strength 

 and weight of the tremendous fore limbs are also greater than 

 could be seen at the present day in the biggest lion or tiger. 

 Nothing (I believe) is known as to the tail of the later and bigger 

 Machairodonts. It is possible that this member may have been 

 short or almost absent (as in the bears). In the only complete 

 skeleton yet obtained of Machairodus neog^us (from South 

 America), the bones of the tail have either been accidentally 

 lost or the creature was as tailless as a bear. But in Hoplophoneus^ 

 an early Machairodont, there was a tail of exceptional length and 

 stoutness. 



In other respects the Machairodont skeleton is remarkably like 

 that of the cat. As in the cats (and hyasnas and bears), the spinous 

 process at the top of the second vertebra of the neck is developed 

 into a huge transverse plate for the attachment and support of 

 the powerful muscles of the head and of the lower jaw. This 

 excessive development of the spinous process of the axis verterbae 

 shows what tremendous force was given to the bite of the 

 Machairodont. Until recently, however, it was an unsolved 

 problem with biologists how the highly developed Machairodonts 

 got their living (so to speak). The sabre tusks were so long 

 that with the ordinary gape of a feline it was impossible that the 

 creature could have opened the mouth sufficiently to obtain 

 a grip or to take a large bite of any substance into its mouth. 

 It was thought that the Machairodonts might have lived by 

 sucking the blood of their victims ; but the problem was how, 

 unless they struck with the closed mouth — which, again, was 

 obviated by the great development of the flanges of the chin — 

 they would be able to pierce the veins. An American palaeonto- 



