MASTODON, a genius of fossil probo scidians of the elephant family, whose remains are found in all parts of the world in Tertiary formations from Miocene time onward to the dawn of the present era. Although in size and external appearance the larger mastodons much resembled modern elephants, save that, like the mammoths, the northern species were probably clothed with long hair, they differed widely from other genera of the family in details of structure, especially those affecting dentition. Thus milk-molars were present, and some times were persistent; and in their structure the fossil molar teeth are not penetrated by deep partitions of cement, and their crowns are marked by few (3 to 5) transveree ridges, which are often broken into nipple-like pro tuberances. This is, in short, the simplest form of tooth-structure in the family, of which the mastodons are the oldest and most primi tive type, and nearest to the earlier Dinotheria. The tusks curved upward only slightly; and their length in Mastodon americanus, whose re mains have been obtained nearly entire from bog-deposits in various parts of the United States, was about nine feet, indicating, as do the measurements of the skeleton, an animal about equal in average height to the modern Indian elephant, but with a rather more bulky body and a flatter forehead. Of this species, which
was a belated survival of an ancient Old World type that became extinct in the Pliocene, sev eral good skeletons are preserved in the muse ums of the United States and Canada, and cer tain European species are also well known. About 30 different kinds of mastodons have been described from bones found in almost every country in the world. In the Pliocene works of Texas, Nebraska and Idaho are found remains of a proboscidian (Stegodon) which was a connecting link between the mastodons and the elephants. What 'brought this wide spread group to an end is not clear. There was no diminution in their food, which con sisted of herbage, bark and leaves, as is known from undigested stomach-contents found within the skeletons; and they survived the historic vicissitudes of climates until subsequently the present settled conditions arrived. There is good reason to believe that they lasted in Amer ica, at least, until after the advent of mankind, but indisputable evidence of this is lacking. See ELEPHANTS; FOSSIL Consult Woodward, Palmontol ogy) (1898) ; Lucas, (Animals before Man in North (1902) ; Scott, 'Land Mam mals of the Western Hemisphere> (New York 1913).