Illustration of late Cretaceous dinosaurs. Family group of tubular-crested hadrosaurs (Parasaurolophus walkeri) and three-horned ceratops (Triceratops prorsus), on extreme left. Late Cretaceous (76-65 million years ago). Reconstructions based on fossils from Dinosaur Provincial Park, Alberta, Canada (Parasaurolophus) and Seven Mile Creek, Niobrara County, Wyoming (Triceratops). Parasaurolophus, a two-ton vegetarian hadrosaur, adorned by an elongated, bony crest that housed a hollow tube connected with the nostrils and throat. It is thought that this structure was used to produce signaling sounds that could be heard for long distances, much like those produced today by elephants and whales for communication. The Triceratops is the largest (5-ton) and best-known of the horned dinosaurs. Like Parasaurolophus, it was also a vegetarian. Triceratops probably had a lifestyle much like the modern-day rhino.