From 38 to 30 million years ago, great herds of Megacerops, rhinoceros-like herbivores also known as Brontotheres, roamed this part of Montana in a warm, damp landscape of lakes, reeds, and other riparian vegetation. Classified as Perissodactyla, they had three toes on their front feet and four on their back feet, stood 8 feet tall at the shoulder, measured around 16 feet long, weighed as much as two tons, and were about as large as African Forest Elephants are today. Megacerops had a branched horn on its snout that may have functioned in mating and defense against predators such as creodonts and nimravids. About 30 million years ago, Megacerops went extinct, and scientists have speculated that climate change, changing vegetation, and the animal's primitive teeth may have contributed to its disappearance. On the Great Plains, Lakota Indians found Megacerops fossils uncovered by rainstorms and called them Thunder Horses because many believed the animal caused thunderstorms when running over the clouds. In the 1860s, settlers in Montana recognized the needs of travelers, and after coming from Scotland to Montana Territory about 1864, James Shedd built toll bridges across the Madison and Jefferson rivers north of Three Forks. He and his wife Elizabeth accepted gold dust from travelers crossing the bridges, built the Bridge House hotel to serve people traveling between the Gallatin Valley and Virginia City and Helena, and by 1871 operated seven toll bridges in the area. A small settlement called Bridgeville grew up around the hotel, and after Shedd sold the operation in 1880, the hotel burned down in 1881.