£/epAas Ya 



^t'e<jodon ^q 



Mo^todon ^/q 



RECENT 



PLEISTOCENE 



UPPERPLIOCENEJ] 



LOmR PLIOCENE \Gomphor/iPnum 



UPPER MIOCENE ] ^"'"''TA/n) 

 mOLEM/OCENE \ 



Hi^roTlon into \ Gomphothe, 



North America 



Jetra^elpdon 'M LOh/ER M/OCENE) 



• (yPPEROLIGOCENE 



LOyEROL/GOCENE\ 



{/on, 



no chin). 



^^ I Po/aedmasfodon 



Pofoeomasrodon 'fy UPPER EOCENE \ {/c^f/h(nin^ c/i/oj 



Moerithenum /^ 



MoeriJhenum 



MWOLE EOCENE \ i^horfchm) 



L OM/S/i iOCEA/E (ancestor un^no^n) . 



Fig. 169. — The evolution of the elephants: On the right the skulls, with the pro- 

 boscis restored in black ; on the left the last lower molar. The principal changes 

 lie in the increased height of the skull and its decreased length with a consequent 

 reduction in number of teeth, also in the development of a long snout or trunk and 

 in the increased length of two or four incisors into tusks. (Tctrabelodon should 

 read Gomphotherium.) (From Scott, after Lull, modified by Sinclair.) 

 (388) 



