Brontotherium
Collier's New Encyclopedia (1921)
or TITANO- THERIUM, a genus of the extinct mammals first found in the Bad Lands of South Dakota, and later in Nebraska and Colorado. The formation is Miocene and the genus is but one of an extinct family of herbivorous mammals. It had the following features: The skull was long and depressed, with a large pair of horn cores, placed transversely on the maxillary bones, in front of the orbits; the nasal bones, which were greatly developed and firmly co-ossified, protruded over the nasal orifice; the brain cavity was small and did not extend over the cerebral hemispheres or the cerebellum, and but little over the olfactory lobes; neck was of medium length and stout; axis was large and extended transversely , being massive, with odontoid process stout and conical; lumbars were slender and not as large as the dorsals, and there were four sacral vertebræ; a long and slender tail, indicated by the caudals; limbs somewhat shorter than the elephant's; radius separated from the ulna; carpal bones short and supporting four toes; tibia separated from the fibula; three toes of almost equal size on the hind foot; the bones all solid. The brontotherium was about the size of the elephant. The nose was evidently flexible, but there was no true proboscis . Eastern world was brought from Cornwall or from the peninsula of Malacca . The word is also applied to a style of calico printing peculiar rather from the character of its colors than from any specific novelty in treatment.
What Has Changed in the Last Century
Collier's placed Brontotherium in the Miocene in 1921; the brontotheres are now dated to the late Eocene, roughly 38 to 34 million years ago, and they died out at that epoch's close rather than surviving into the Miocene. The name itself has largely gone: under the rules of zoological naming, Brontotherium, Titanotherium and Brontops are today treated as synonyms of Megacerops, described earlier by Leidy, so the animal Collier's describes usually appears now as Megacerops. The paired horns are also understood differently, being built from the nasal and frontal bones rather than sitting on the maxillae as the 1921 text has it, and are generally read as weapons for flank-butting contests between males. The comparison to an elephant's bulk still holds, though brontotheres are placed with the odd-toed hoofed mammals, distant relatives of horses and rhinos, not with elephants at all.
Written for this edition, 2026.