TITANOSAURUS, or ATLANTOSAURCS. A genus of extinct. sauropodons. herbivorous ditto• saurs found fossil in the Jurassic rocks of the Rocky Mountain region and Dakota. whose species were among the most gigantic land ani mals that over existed, one specimen. exhumed in Colorado by 0. C. Alorsb. measuring about 60 feet long and standing about 30 feet high. The characteristics of the genus were similar to those of its near relatives Brontosaurus and Diplo docus (qq.v.).
TANOTHEiRIUNI (Neo-Lat., from Gk. Trrifv, Titan + Onplov, therion, diminutive of Ohp, tiler, wild beast). The type genus of a family, Titanotherida., of ungulates, occurring in the Oligocene formations of North America, and comprising a number of species of gigantic ani mals somewhat resembling the rhinoceros in general form. Though belonging to the perisso dactyles, they approximate the artiodactyles or even-toed ungulates in certain structural points. especially of the vertebrae and limb-bones. The most striking feature of the titanotheres is a pair of bony processes resembling horn-cores, which grow upward and outward from the maxillary bones above the snout. These prominences are variable in development according to age and sex, and also differ in size and form in different spe cies to such an extent that many generic names, such as menodus, brontotherium, brontops, and titanons, have been bestowed upon forms which later study has shown to be only different stages in the evolution of the same genus. Careful com
parative study of the remains from the White River Beds of Canada. South Dakota, Colorado, and Nebraska shows that during the Oligocene period the genus increased in size, and the horns, which are mere knobs in the (presumably) earlier types, such as Titanothcrivm hcloceras, increased greatly in length, and became flattened and wide-spreading in the later species, culmi nating in the highly specialized Titanotherium and Titanotherivm platyceras—the last survivors of their race. Of some forty spe cific names which various writers have proposed, often on the basis of a single fragmentary skull, only a few designate sharply marked species. One of the best-known titanotheres is Titanotheriunt robustum, a form with moderately developed horns, which measured nearly 14 feet in total length, and eight feet in height at the shoulder.