The word dinosaur means 'terrible lizard' and was coined in 1842 to describe the impressive size of dinosaurs rather than their appearance. Dinosaurs ruled the Earth for over 160 million years from around 230 million years ago until 65 million years ago. Some dinosaurs grew to lengths of nearly 40 meters long and heights of 18 meters tall, weighing up to 70 tonnes. Brachiosaurus was first discovered in Colorado in 1900 based on an incomplete skeleton described by paleontologist Elmer Riggs, while Werner Janensch found many fossils in Tanzania, Africa.