The thyreophorans, the armored dinosaurs, evolved in the Early Jurassic and soon grew to be the dominant low browsers of the middle Mesozoic evolving into (among other things) the famous stegosaurs in the Middle Jurassic. Stegosaurs went extinct soon after the end of the Jurassic, in the Early Creataceous (but with a possible Late Cretaceous record), but the more heavily armored thyreophorans, the ankylosaurs, survived, and by the end of the Cretaceous, existed in two major groups, the immense, tank-like, club-tailed ankylosaurids, and the somewhat smaller, less well armored nodosaurs. Both groups diversified throughout the Early and middle Cretaceous, with the ankylosaurs ranging across Eurasia and North America, while the nodosaurs spread across the globe. Nodosaur fossils have been foun