Mastodon
2 of the 6 encyclopedias on this shelf carry an entry for Mastodon. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
an extinct genus of proboscideans, closely allied to the true elephants. The crowns of the molar teeth have nipple-shaped tubercles placed in pairs, and from the number of these projections Falconer divided the genus into groups: (1) Trilophodon, and (2) Tetralophodon. Generally speaking, the two upper incisors formed long curved tusks, as in the elephants, but in some cases there were two lower incisors as well. The genus ranged in time from the middle of the Miocene period to the end of the Pliocene in the Old World, when they became extinct. In America several species especially that which, from the abundance of its remains, is the best known, M. ohioticus americanus, or giganteus-survived to a late Pleistocene period. In 1897 the skeleton of a mastodon, the largest yet discovered, was unearthed on a farm near New Paris, O. It was found in what had evidently at one time been a morass, and was buried 10 feet below the surface, where from all indications it had lain for centuries. It was very nearly perfect, and though some of the bones crumbled away on exposure to the air, they were cleverly replaced. The mastodon is believed to have been for some time a contemporary
Aiton's Encyclopedia (1910)
an extinct member of the elephant family, closely related to the mammoth. It is known only from skeletons. A very nearly perfect skeleton was found in Missouri in 1840. It is now preserved in the British Museum . The dimensions are as follows: Length, 20 feet 2 inches; height, 9 feet 6 inches; length of head, 3 feet 6 inches; width of foot, 2 feet 11 inches; length of trunk, 7 feet 2 inches; circumference of trunk at base, 27 inches. Another fine skeleton, found at Cohoes, New York , in 1866, is now preserved in the State Museum of Natural History at Albany. Scientists are unable to account for the extinction of this huge animal. It appears to have roamed the valleys of Europe, and especially those of North America , in large herds. It was too large to be destroyed by other animals, and there is no evidence that its food supply gave out. Some of the skeletons are so perfect that remnants of grass, herbs, and leaves have been found in the stomach. See Mammoth ; Elephant
What Has Changed in the Last Century
Aiton's called the mastodon "closely related to the mammoth," and Collier's placed it in the genus Mastodon; both labels have since gone. The American mastodon is now Mammut americanum, in its own family, Mammutidae, a browsing lineage that split from the ancestors of elephants and mammoths tens of millions of years ago, while Collier's tooth-based groups Trilophodon and Tetralophodon have been dispersed among the gomphotheres. Aiton's wrote in 1910 that "scientists are unable to account for the extinction of this huge animal"; radiocarbon dating, developed after 1949, now puts the last mastodons at roughly 11,000 years ago, at the close of the Pleistocene and within a few thousand years of the arrival of people in North America, and the argument today is over how much of the blame falls on hunting and how much on the warming climate that replaced its spruce forests. Mastodon mitochondrial DNA has also been recovered and sequenced, something no one in 1921 could have imagined, and it is now used as an outgroup for dating the elephant family tree.
Written for this edition, 2026.