Feb,, 1904,] 



KNOWLEDGE cS: SCIENTIFIC NEWS. 



II 



The Ancestry of the 

 Elephants, 



By A. Smith W'oodwakh, LL.D., I'.K.S. 



LoxG before the ancestry of the horses and camels liad 

 been discovered in North America, some of the im- 

 mediate fore-runners of the elephants had been.reco^'nised 

 and discussed in the Old World. The disco\eries of 

 Falconer and Cautley in India, of Falconer, Gaudry, and 

 others in fiurope, had made it evident that the elephant 

 was derived by gradual stages from a more normal kind of 

 quadruped. These gradations, however, could only be 

 traced back as far as the Middle Miocene period, and no 

 known animal of earlier date could be claimed as ancestral 

 to the series. Lower Miocene and Eocene quadrupeds 

 continued to be discovered in abundance, but never any 

 trace of an elephantoid creature. The natural conclusion 

 therefore was that the race of elephant-like animals only 

 reached Europe and .\sia in the early part of the Miocene 

 period by migration from some other region in which the 

 early stages of their tribal history were passed. It e\entu- 

 ally became probable that the .\frican continent would 



or trunk. It is, in short, the story of a rare wliicli once 

 fed in a normal manner on succulent weeds, browsing like 

 any other herbivore, but afterwards began to subsist on 

 drier or harder vegetation, and at the same tiiiK- lost the 

 power of reaching the ground witii its mouth, depending 

 for help on a modification of the snoul which is elsewhere 

 unknown. 



The oldest recognised member of this race is the small 

 Moefitlicriiini (lig. i) from the Middle Ivocciie of I'-gypt. 

 It comprises species not much larger than the existing 

 tapirs, and they possess a neck sufficiently long and 

 tlexible to have allowed theui to browse in the ordinary 

 way. The skull of Moivithcriitui shows that it did not 

 support more than a rudimentary proboscis, but there are 

 certain features in its structure which suggest a tendency 

 towards arrangements now specially characteristic of the 

 elephants proper. The teeth are disposed in a long scries, 

 and are nearly as numerous as in any of the early ijuadru- 

 peds. In the upper jaw there are the usual three pairs 

 of front cutting teetii or incisors, but the second pair is 



Fig. I. — Sloeritherium byomi , left side-view of skull, upper view of 

 mandible Ia|. and diagrammatic section of last molar tooth (B). — 

 Middle Eocene ; Eg\-pt. 



yield these ancestors, and students of extinct animals 

 began to look with confidence to that part of the world. 

 Their expectations have not been disappointed ; for the 

 recently-published researches of Dr. Charles \V. Andrews 

 on early Tertiary Mammalia from Egypt" have furnished 

 precisely the missing links that were desired. The evolu- 

 tion of the elephant-tribe is now almost as well known as 

 that of the horses, camels, and their allies ; and Africa is 

 proved to have been its ancestral home. 



The body of the elephant has changed very little during 

 its long geological history. It has always retained the 

 simple limbs with five toes and unaltered wrist and ankle. 

 It has merely become a little shortened in proportion to 

 its height, while the supporting limbs have grown in 

 stoutness as the successive representatives of the tribe 

 have increased in size and weight. In fact, it is permis- 

 sible to describe the massive frame of a modern elephant 

 as essentially an overgrown copy of the skeleton of a 

 herbivorous quadruped of the early Eocene period. 



All the features which make elephants unique among 

 Mammalia are therefore to be obser\ed in the head and 

 neck. The story of their evolution is concerned mainly 

 with the gradual enlargement of their tusks and com- 

 plicated grinding teeth, and with the eventual grow'th of 

 a peculiarly flexible, boneless, and prehensile prolongation 

 of the face, which is commonly known as the proboscis 



I-"l<i. z.—Paliioviastodon headncUi : left side-view of skull, upper view of 

 mandible (a), and diagrammatic section of last mohir tooth IB.) — 

 Upper Eocene ; Kyypt. 



much larger than the others, and forms conspicuous 

 downwardly-curved tusks. Small canines, or corner 

 teeth, are also present; and there are six grinding teeth 

 on either side (three pre-molars and three molars), most 

 of them bearing two cross-ridges, the hindermost also 

 with a third small posterior ridge (fig. ib). The lower 

 jaw (fig. ia) likewise has six grinding teeth, of which the 

 molars closely resemble those of the upper jaw ; but 

 canine teeth are absent, and there are only two pairs of 

 incisors, the outer pair being mucli the larger. The jaws 



" " On the Evolution of the I'roboscidea, 

 pp. 99-1 iS. 



I'bil. Trans , 19031;, 



Section lb. 



are narrow, but there is no conspicuous prolongation of 

 the chin (or mandibular symphysis). 



The next genus, from the Upper Eocene of ICgypt, is 

 much more clearly elephant-like. It is named I'alao- 

 maitodon (fig. 2), and comprises species somewhat more 

 than twice as large as any of the earlier kinds of Moeri- 

 thcriiim. A peculiar elongation of tlie skull and a long, 

 spout-shaped growth of the bone of the chin (mandibular 

 symphysis) are now very noticeable, and all the incisor 

 teeth except one pair have disappeared above and below_ 



