Diston 

 Thunder 



by Bryn J. Mader 



Long before people of European de- 

 scent came to the Great Plains of North 

 America, the remains of extinct creatures 

 that would later be called titanotheres were 

 known to the native inhabitants of this re- 

 gion. Many fossil bones of these mysteri- 

 ous "titan beasts" had weathered out in the 

 Badlands, and over time, the bones were 

 woven into legend. According to the 

 Sioux, the bones were those of the great 

 "thunder horse," a gigantic creature that 

 would occasionally descend to earth to 

 hunt buffalo. 



Western science first learned of titan- 

 otheres in 1 846, when a fur trader brought 

 an unusual fossil to Hiram Prout, a med- 

 ical doctor living in Saint Louis. The fos- 

 sil, a section of a massive lower jaw, had 

 been found in the Badlands, along the 

 White River in what is now South Dakota. 

 Front's specimen, which is still preserved 

 in the collections of the Smithsonian Insti- 

 tution, has a double significance because it 

 was also the first fossil land vertebrate to 



be collected from the western territories of 

 the United States. The strange fossil 

 caused much excitement in scientific cir- 

 cles and was largely responsible for the 

 geological exploration of the territories in 

 the decades that followed. All of the spec- 

 tacular discoveries of dinosaurs and giant 

 mammals in the American West owe 

 much to the finding of this first, fragmen- 

 tary fossil. 



After the discovery of the first titano- 

 there specimen, more than a quarter cen- 

 tury passed before scientists began to 

 piece together an accurate picture of what 

 titanotheres were truly like. Not surpris- 

 ingly, the image that emerged was quite 

 different from the fabulous creatures of 

 Sioux legend; nevertheless, titanotheres 

 turned out to be extraordinary animals. 



Titanotheres belong to the mammalian 

 order Perissodactyla, which includes mod- 

 em-day horses, tapirs, and rhinoceroses, 

 and are members of a distinct perisso- 

 dactyl family known as brontotheres 



(which means "thunder beasts"). Al- 

 though many titanotheres were superfi- 

 cially rhinoceroslike in appearance, they 

 were a distinct lineage and left no descen- 

 dants in our modern world. 



Titanotheres appeared in western North 

 America in the early Eocene, approxi- 

 mately fifty-one million years ago, and 

 soon spread across the Bering land bridge 

 into eastern Asia. The earliest titanothere, 

 Eotitanops borealis, was a relatively small 

 creature, no bigger than a large dog. Over 

 the course of their twenty-million-year 

 history, however, fitanotheres evolved into 

 giants such as Megacerops platyceras, 

 more than seven feet high at the shoulder. 



The titanothere was massive and pow- 

 erfully built. It had four hooflike toes on its 

 front feet and three on the hind feet. The 

 head was oddly proportioned, with an ex- 

 tremely short face on an otherwise elon- 

 gated skull. Both eyesight and smell were 

 pooriy developed, and the brain was extra- 

 ordinarily small. In a giant skull more than 

 three feet long, the brain was only slightly 

 larger than a human fist. 



Like all perissodactyls, titanotheres 

 were herbivores. Their very low-crowned 

 teeth suggest that they fed primarily on 

 soft leaves. On occasion, they may have 

 eaten grass, but it does not seem to have 

 constituted a large part of their diet. Grass 

 is a highly abrasive substance that wears 

 teeth down very quickly. If titanotheres 

 subsisted primarily on grass, their teeth 

 would have been worn to stubs in a very 

 short period. 



Perhaps the most conspicuous feature 

 of many titanothere species were the horns 

 located on the front of the skull. Titanoth- 

 ere horns differed from those of modem- 

 day antelope and cattle in that they were 

 blunt and covered with tough hide rather 

 than with a homy sheath. They were pre- 

 sent in both sexes, and in primitive homed 

 species, the horns of males and females 

 were about the same size. In the gigantic 

 forms of later eras, however, the homs of 

 males were larger than those of females. 



On exhibit at the American 



Museum, a skeleton of the 



titanothere Brontops 



reveals a broken and 



subsequently healed rib 



(fourth rib visible from 



front). Such an injwy could 



have resulted fivm rivalry 



between herd members. 



Photograph by Denis Finnin; AMNH 



61 



