These were the ‘cattle’, of the Dinosaurs. They were very, very common, reasonably large (most were around 10 metres long, though the largest Asian Hadrosaurs reached up to 17 metres long) and rather unintelligent. Theropods of the Mid-Late Cretaceous (when the Hadrosaurs appeared) favoured these animals as prey items, as the Hadrosaurs’ primary means of defence, was only to run, as they lack defensive armour or weaponry to fight back. During their time, they spread far across the globe, becoming the dominant herbivores, wherever they went. Many different kinds of Hadrosaur evolved, from the Hadrosaurus itself ( the namesake of the whole suborder) to the Anatotitan, the second largest American Hadrosaur, only second to Lambeosaurus. These Dinosaurs had the most teeth of any Dinosaurs, using batteries of thousands of grinding teeth packed together like blocks, to process tough vegetation. Hadrosaurs, like all Dinosaurs, became extinct, 65 million years ago.